Dr Gérard

Virginie Nowak

Marie Christine Breuil

Marie-Jeanne Milloux

Mireille Boilletot

Hi Crome Selective

Annex 5 : Measurements of water potential (hPa) in Gačnik in 2004 and 2005

Keywords: Calcaric Cambisol, Dystric Cambisol, soil quality, soil health, orchards, drip irrigation, slope, organic fertilizing, liming, structural stability, fresh and sedimentary organic matter, microbial biomass, pathogens CALCOSOLS, ALOCRISOLS, qualité des sols, santé des sols, vergers, irrigation au goutte à goutte, agriculture biologique, chaulage, stabilité structurale, matière organique sédimentaire, biomasse microbienne, bactéries pathogènes POVZETEK Compound-specific isotope analysis. Application to archaelogy, biomedical sciences, biosynthesis, environment, extraterrestrial chemistry, food science, forensic science, humic substances, microbiology, organic geochemistry, soil science

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RÉSUMÉ ÉTENDU

Une mauvaise connaissance des propriétés des sols et de leur fonctionnement peut avoir de nombreuses conséquences néfastes sur le rendement et la qualité des récoltes, sur la dégradation des sols et sur une pollution de l"environnement. En raison de l"importance des pratiques agricoles, notre étude s"est focalisée sur leur impact sur la qualité et la santé des sols. La recherche s"est effectuée de novembre 2003 à octobre 2007 sur des vergers de pommiers implantés sur des collines dans le nord-est de la Slovénie. Deux pratiques agricoles fréquentes dans cette région ont été suivies : (i) une irrigation localisée au goutte à goutte sur des Calcaric Cambisol (CALCOSOL) développés sur marnes, et ses effets sur la stabilité structurale des sols et leur biomasse microbienne à la Station expérimentale de Gačnik et (ii) la combinaison d"un engrais organique (Compo guano) et d"un amendement calcaire dans un verger conduit en agriculture biologique à Pohorski dvor sur un District Cambisol (ALOCRISOL) développé sur schistes. La présence de microbes pathogènes fécaux dans le sol, dus à l"irrigation ou à l"apport d"engrais organiques animaux a aussi été recherchée sur les deux sites.

Le régime hydrique du sol a été suivi durant deux étés par des relevés tensiométriques hebdomadaires sur les deux sites. A la station expérimentale de Gačnik, un rang irrigué a été comparé à un rang non irrigué. La teneur en matière organique totale, son fractionnement granulométrique et la signature isotopique des différentes fractions permettant de discuter de leur origine et leur turn over ont été mesurés. La biomasse microbienne et son activité ont été caractérisées au printemps et à l"automne en 2004 et 2005. La stabilité structurale a été mesurée selon la méthode de Bartoli à l"automne 2004 et au printemps 2005. Sur le verger conduit en agriculture biologique à Pohorski dvor seul le pH et les paramètres microbiologiques ont été suivis selon la même périodicité en comparant les différents traitements dans une expérimentation par blocs. Enfin, sur les deux sites, une quantification des champignons, des bactéries (aérobies, anaérobies, coliformes fécaux) et des virus présents dans le sol a été réalisée.

Incidence de l'irrigation par goutte à goutte sur la qualité du sol sur le site de Gačnik sur la qualité physique du sol-Les sols de ce verger, argilo-limoneux et carbonatés, varient fortement de l"amont à l"aval de la parcelle située sur une pente de 15%. le sol est peu épais à l"amont, la marne altérée apparaissant dès 60 cm tandis qu"à mi-pente et à l"aval le sol est épais >1 m et la marne plus fortement altérée. L"observation des profils pédologiques et l"historique de la parcelle montrent que le sol a été fortement remanié sur les 60 premiers centimètres préalablement à la plantation du verger. Le passage d"une plantation en terrasses à une plantation dans le sens de la pente a conduit à l"effacement des terrasses suivi d"un labour profond dont en voit encore la trace à 60 cm de profondeur à l"aval de la parcelle (Fig. 3.3 & Tab. 3.9). Un échantillonnage systématique de la teneur en carbone organique de l"horizon de surface, selon un pas de 6 m, montre un accroissement selon la pente suivant une forme en zig-zag reflétant la trace des anciennes terrasses (Fig. 3.19).

Dans les 30 premiers centimètres la teneur en matières organiques, le rapport C/N et la capacité d"échange cationique augmentent de l"amont vers l"aval tandis la teneur en carbonates de calcium décroît (Fig. 3.15). Le pH reste stable entre 8 et 8, 4. A la surface du sol dans les rangs de plantation traités par désherbage chimique, une croûte alguaire se forme sur le côté ombragé du rang. L"effet de la pente va être dominant sur les caractéristiques fonctionnelles du sol : la teneur en eau pondérale (W) (Tab. 3.25 & 3.26), la biomasse microbienne (MB) (Fig. 3.42) et sa respiration (R) augmentent vers l"aval ; tandis que la stabilité structurale (SS) diminue (Tab. 3.25 & 3.26;Fig. 3.44). L"effet de l"irrigation se perçoit cependant : en comparant le rang non irrigué au rang irrigué, on observe une baisse de la teneur en eau pondérale (Fig. 3.27 à 3.30) et de la stabilité structurale (Fig. 3.45) tandis que seule la fraction grossière de la teneur en matière organique et son rapport C/N augmentent (Tab. 3.17 & 3.18) de même que la biomasse (Fig. 3.31,3.33,3.40,3.42) et la respiration microbienne (Tab. 3.23 & 3.24). L"irrigation en revanche n"a pas d"influence sur la teneur en carbonates de calcium (Tab. 3.16).

La variation de la stabilité structurale en fonction de la pente s"explique par les contributions respectives du carbonate de calcium et de la matière organique qui se compense entre l"amont et l"aval. En fonction de l"irrigation, la teneur en eau pondérale plus faible en surface dans le rang irrigué pourrait s"expliquer par la modification de l"architecture du système racinaire du pommier provoqué par l"irrigation au goutte à goutte. L"irrigation conduit à une augmentation de la biomasse microbienne et de son activité à court terme et à long terme, à une réduction de la teneur en matières organiques. Nous avons de plus constaté, grâce à la signature isotopique du carbone sur les différentes fractions granulométriques (Tab. 3.31et Fig. 3.24) (i) qu"une partie du pool de matière organique du sol provenait de l"altération de la marne, (ii) que cette matière organique d"origine sédimentaire était majoritairement présente dans la fraction granulométrique la plus fine et dominait à l"aval du versant et enfin (iii) que l"irrigation, en augmentant la biomasse microbienne et son activité, conduisait à une minéralisation d"une partie de ce stock de carbone d"origine sédimentaire. La stabilité structurale plus faible du rang irrigué doit être reliée à la baisse de la teneur en matière organique de ces rangs. Les variations saisonnières de la stabilité structurale en fonction de la position dans le versant et du traitement irrigué ou non sont complexes et résultent de la combinaison de l"effet du climat de l"année de l"activité biologique.

Incidence de la fertilisation organique et du chaulage -Concernant la fertilisation organique, l"apport conjoint de Compo Guano et d"un amendement calcaire sur ce sol limono-argileux acide est vraisemblablement le meilleur compromis sur le long terme sur la qualité chimique et biolobique du sol parce qu"il présente des effets positifs à la fois sur le pH et sur l"azote disponible tout en maintenant à un bon niveau la biomasse microbienne et la teneur en matière organique labile. Geological map of exposed bedrock in the surrounding of Maribor; insert from Geological map of Maribor 1:100 000 [START_REF] Buser | Basic geological map of SFRY[END_REF] ......................

Figure Index

Fig. 2.4:

Monthly distribution of precipitations and average temperature in Maribor (1961Maribor ( -1990) ) Spec. respiration (day

General introduction

GENERAL INTRODUCTION

The research, which took place from November 2003 to October 2007, was focusing on the impact of different agricultural practices on soil quality in apple orchards in North-East Slovenia. For this reason, two important agricultural practices -irrigation and organic fertilising -were chosen, in different apple productions -integrated and organic and on two different soil types -Calcaric and Dystric cambisol. For improving the yield, irrigation is almost necessary agricultural practice in Slovene fruit production, while organic farming represents an alternative way to produce more natural food with low chemical input. Both of these practices are supported by Slovene government and the extent of both is getting bigger every year. Both have some advantages and disadvantages for fruit production and for the environment, especially if they are not performed well. The main idea was to study two different practices with completely different soil types to have a wider view of soil behaviour in orchards and try to find the most appropriate solution of applied agrotechnical techniques on soil quality. Instead of focusing on yields, as in most agricultural studies, we focused on soil, with emphasis on basic soil microbiological properties. In our study we are trying to make more comprehensive assessment for soil quality by searching for some useful soil indicators for orchards.

In the first part we are dealing with irrigation practice including slope and their effects on soil properties, especially on soil structure and soil microbes. The second part is dealing with the possibility of enhancing microbial biomass and nitrogen nutrition with different combinations of organic fertiliser and liming.

In both experiments, micro organisms play the main role in soil quality and soil health, which might affect both yield and environment. Also their role in food safety and human health is important, because, as already stated, irrigation water or organic fertilizers can be the potential sources of some dangerous pathogens. The challenge is therefore to improve knowledge of soil science and soil microbiology in agricultural practices, not just for scientific purposes but also to share both basic and practical knowledge with farmers and consumers.

Despite the different problems, we have just one common goal: to remain good soil condition for sustainable plant production and minimise the risk to produce infected fruit by pathogens (food safety). Both aspects of the study are complex, so the main objective of this thesis is to initiate a huge work and to issue some guidelines for further investigation.

By analysing some physical and microbiological properties in one realistic field experiment with irrigation system, it is possible to show some new perspectives to the producers and more attention might be paid to some important soil facts, which were overlooked before. For improving benefits of irrigation systems, we need a more comprehensive approach for estimating soil quality. This evaluation requires focusing not only on chemical (fertility) considerations, but also on the dynamic soil conditionsa combination of physical, biological, and chemical characteristics, which are directly affected by recent and current land use decisions and practices.

In relation with irrigation, the aims of our project are:

-to define the effect of irrigation and slope on soil physics, chemistry and soil microbiology; -to determine the connections between microbial indicators and (especially) physical properties of soils, with the interpretation of the results in the case of irrigation; -to propose microbial indicators which could be useful for assessing soil quality, health and sustainability in the case of irrigation; -to contribute to the knowledge of side-effects of irrigation on soil ecology; -to enable a comprehensive approach, including soil physical and microbial properties; -to control irrigation water and soil for possible water or soil-born pathogens.

We will intend to examine the following hypotheses:

1. Irrigation and slope affect soil microbial biomass and microbial activity.

2. Irrigation and slope affect soil physical parameters (bulk density, structural stability, water regime), and organic matter dynamics.

3. The relationships between soil physical properties and soil microbial parameters are controlled by water supply and slope.

4. Microbial and physical soil indicators are appropriate for assessing soil quality in case of irrigation.

Irrigation water can represent a potential source of pathogens.

To improve nitrogen nutrition in organic plant production, it is important to focus on microbes, which enable the release of available nitrogen forms in soil. In organic production, the use of inorganic nitrogen fertilisers is not allowed, so plant nitrogen nutrition represents one of the important problems in organic plant production. Organic farmers are replacing service with direct available forms of nitrogen in artificial fertilisers with the application of organic fertilisers, which have indirect an affect on nitrogen nutrition via microbial mineralization processes. To optimise the effectiveness of these processes, the basic conditions (pH, humidity, aeration, C/N) for microbial activity should be improved. Our attention should be focused first on basic soil properties and their improvement, in view of getting as good as possible conditions for successful microbial activity. Another important thing is to apply the appropriate form(s) of organic fertilisers: fertilisers obtained from treated organic matter are safer in sense of having dangerous pathogens.

In relation with organic fertilising, the aims of our project are:

-to elucidate the effect of applied organic matter on nutrient cycling, soil chemistry and soil microbiology (microbial biomass and microbial activity); to elucidate the effect of organic mater (used as fertilizer) and liming on soil pH and mineralization processes; to propose microbial indicators which could be useful for assessing soil quality and soil health in orchards; to compare behavior of microbes under organic fertilizing and liming in two different soil types according to water conditions; to control presence of some pathogens in soils.

Chapter 1

Literature review Chapter 1: Literature review

Interest in evaluating the quality and health of our soil resources has been stimulated by increasing awareness that soil is a critically important component of the earth"s biosphere, functioning not only in the production of food and fibre but also in ecosystems function and the maintenance of local, regional, and global environmental quality [START_REF] Glanz | Saving our Soil: Solutions for Sustaining Earth's Vital Resource[END_REF]. With the suspected increasing degradation of agricultural soils, there is a great need for sustaining the soil resource and enhancing soil quality. An assessment of the impact of changing soil management should therefore ideally include some measure of soil health or quality, as this is inseparable from issues of sustainability [START_REF] Doran | Defining and assessing soil health and sustainable productivity[END_REF]. In this way, soil quality has become a tool for assessing the sustainability of soil management systems [START_REF] Schloter | Managing soil quality[END_REF]. Soil quality is increasingly proposed as an integrative indicator of environmental quality (National Research Council, 1993), food security [START_REF] Lal | Soil quality and food security: the global perspective[END_REF] and economic viability [START_REF] Hillel | Out of the Earth: Civilization and the Life of the Soil[END_REF]. Therefore, soil quality assessment is also a useful indicator of sustainable land management.

I. Definitions of soil quality and soil health

The soil is a basic source of agricultural production. It represents at the same time the area of the important life processes and the living place for many different living organisms [START_REF] Atlas | Microbial ecology: fundamentals and application[END_REF]. Being a complex medium, soil is quite difficult to evaluate.

In the past the identification of fertility was based on the capacity to support agricultural production. Nowadays, soil quality includes a broad range of functions and services it performs. A variety of definitions have been proposed for the term of soil quality by soil scientists in the last decades (de Han et al., 1990;[START_REF] Chaussod | La qualité biologique des sols : évaluation et implications[END_REF][START_REF] Máté | Soil bonitation as a constituent of land evaluation (Talajbonitáció mint a földértékelés egyik tényezõje) -Agrárökonómiai Tudományos Napok[END_REF][START_REF] Bouma | The land use system approach to planning sustainable land management at several scales[END_REF]Doran and Safley, 1997;[START_REF] Karlen | Soil Quality: A Concept, Definition and a Framework for Evaluation[END_REF][START_REF] Sojka | Reservations regarding the soil quality concept[END_REF][START_REF] Davidson | Soil quality assessment: recent advances and controversies[END_REF][START_REF] Doran | Soil health and sustainability: managing the biotic component of soil quality[END_REF][START_REF] Loveland | Identification and development of a set of national indicators for soil quality[END_REF]Tóth et al., 2007), ranging from a purely agricultural point of view to a more environmental perspective. The Soil Science Society of America (SSSA) and [START_REF] Karlen | Soil Quality: A Concept, Definition and a Framework for Evaluation[END_REF] had proposed a definition, which presents an integration of scientific knowledge with practical approach. The description of soil quality by SSSA as "The capacity of a specific kind of soil to function, within natural or managed ecosystems boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and support human health and habitations" can be regarded as one of the most comprehensive definition. Soil quality can be briefly defined as the sustainability of a soil for a specific use [START_REF] Gregorich | Towards a minimum data set to assess soil organic matter quality in agricultural soils[END_REF].

Soil quality is an increasingly popular concept, especially for its biological aspects, and "soil health" is even used as a synonym in some countries. The biological characteristics of soils are in close interaction with physical and chemical properties on one hand, and are more or less modified by human activities on the other [START_REF] Chaussod | La qualité biologique des sols : des concepts aux applications[END_REF]. For cultivated soils, it is possible to identify four main aspects of quality: 1) fertility (ability of the soil to provide crops with nutriments and other growth factors), 2) sanitary aspects (contamination by pathogens, pests or weeds), 3) environmental aspects (impact of soil functioning on other compartments of the ecosysteme.g. effect on water and air quality) and 4) resilience (ability to resist and recover all biological activities after a physical or chemical stress) [START_REF] Chaussod | La qualité biologique des sols : évaluation et implications[END_REF].

According to Tóth et al. (2007), soil quality refers to its ability to provide ecosystem and social services and to maintain such functions under changing conditions. The concept of soil quality expressed by this definition allows practical applications with regards to targeted social and/or ecosystem services. The evaluation scheme has to consider the two basic elements of soil quality: (1) functional ability and (2) response properties. These two elements reveal the (1) capacity to perform a function under given conditions and the (2) range of the functioning capacity under changing conditions. Soil quality evaluation must therefore be performed with special regards to the goal of the assessment (Toth, 2008).

The term soil health is preferred by some (Doran et al., 1996;Doran and Safley, 1997), because it portrays soil as a living, dynamics system whose functions are mediated by diversity of living organisms. Good management and conservation practices are required because soil health, biodiversity, and soil resilience are sensitive to anthropogenic disturbance [START_REF] Freckman | Low-diversity Antarctic soil nematode communities: Distribution and response to disturbance[END_REF]. Balance between soil function for productivity, environmental quality, and plant and animal health is needed for optimal soil health [START_REF] Doran | Soil health and global sustainability: translating science into practice. -Agriculture[END_REF]. The concept of soil health includes the ecological attributes of the soil which have implications, beyond its quality, on its capacity to produce particular crops. These attributes are chiefly those associated with the soil biota: diversity, food web structure and activity for a range of functions [START_REF] Pankhurst | Biological indicators of soil health[END_REF]. Soil biodiversity per se may not be a soil property that is critical for the production of a given crop, but it is a property that may be vital for the continued capacity of the soil to support that crop [START_REF] Pankhurst | Biological indicators of soil health[END_REF]. Current technologies for increased agricultural production have largely ignored this vital management component.

Soil health focuses more on the biotic components of a soil, reflecting the maintenance of soil organisms and their proper functioning as regulators of nutrient cycling and soil fertility. In the related literature both terms are intermingled and it can be considered that soil quality encompasses soil health [START_REF] Anderson | Microbial eco-physiological indicators to assess soil quality. -Agriculture[END_REF]. Soil biota can increase or reduce agricultural productivity, depending on its composition and the targets of its different activities [START_REF] Blume | Surface and subsurface microbial biomass, community structure and metabolic activity as a function of soil depth and season[END_REF][START_REF] Degens | Decreases in organic C reserves in soils can reduce microbial functional diversity[END_REF]. Conversely, farming practices modify soil life, including the total number of organisms, the diversity of species and the activity of these organisms, including the formation of aggregates by soil biota. These changes can be beneficial or detrimental to the soil biota and its functions and its regenerative capacity. The improved management of soil biota could play a vital role in maintaining soil quality (or health) and in achieving the goals of agricultural production and food security through sustainable land use and land resource management (Convention on Biological Diversity, 2001). Soil quality assessment, and especially the identification of key soil properties which can serve as indicators of soil health, became a major issue for land managers and for food producers throughout the world.

II. Indicators of soil quality and soil health

The success of management in maintaining soil quality depends on our understanding of how soil responds to agricultural use and practices over time [START_REF] Gregorich | Towards a minimum data set to assess soil organic matter quality in agricultural soils[END_REF]. Therefore, methods to quantify soil quality must assess changes in selected soil attributes over time. However, soil quality cannot be measured directly from the soil alone, but is inferred from soil characteristics and behaviour under defined conditions. Furthermore, there is no single measurement that can quantify soil quality [START_REF] Stewart | Advances in Soil Science -20[END_REF], but there are certain soil properties that could be good indicators when considered together.

Understanding the response of soils to agricultural practices over time helps to evaluate whether the investigated practices maintain or improve soil quality. Traditionally, the quality of soil has been mainly associated with its productivity (Hornik, 1992), but nowadays the concept of soil quality is much more comprehensive. Soil quality depends on a large number of chemical, physical and biological properties, and its characterization requires the selection of properties most sensitive to changes in management practices [START_REF] Yakovchenko | A biologically based indicator soil quality[END_REF].

Good indicators of soil quality must be related to ecosystem processes, integrating physical, chemical, and biological properties. They must be sensitive enough to management and allow analytical accessibility and practical utility to agricultural specialists, producers, conservationists, and policy makers [START_REF] Doran | Quantitative indicators of soil quality: a minimum data set[END_REF]. Initially, the use of a basic set of indicators to assess soil quality in various agricultural management systems was proposed. While many of these key indicators are extremely useful to specialists (i.e. researchers, consultants, extension staff, and conservationists), many of them are beyond the expertise of the producer [START_REF] Hamblin | Environmental indicators for sustainable agriculture[END_REF]. However, the use of simple indicators of soil quality which have meaning to farmers and other land managers will likely be the most fruitful means of linking science with practice in assessing the sustainability of management practices [START_REF] Romig | How farmers assess soil health and quality (Special Issue on Soil Quality)[END_REF]. Although soils have an inherent quality as related to their physical, chemical, and biological properties within constrains set by climate and ecosystems, the ultimate determinant of soil quality and health is the land manager. As such, the assessment of soil quality and direction of change with time is a primary indicator of sustainable management [START_REF] Doran | Soil health and global sustainability: translating science into practice. -Agriculture[END_REF][START_REF] Karlen | Soil Quality: A Concept, Definition and a Framework for Evaluation[END_REF].

To assess soil quality, indicators (soil properties) are usually linked to a specific soil function [START_REF] Howard | Soil protection and soil quality assessment in the EC[END_REF][START_REF] Larson | The dynamic of soil quality as a measure of sustainable management. Defining Soil Quality for a Suitable Environment[END_REF][START_REF] Karlen | Use of soil quality indicators to evaluate conservation reserve program sites in Iowa[END_REF]Doran et al., 1996) e.g., as a medium for plant growth, and reflect changes over various spatial and temporal scales. To perform as good indicators, the selected soil properties should be sensitive, easy to measure, verifiable, and well-related to land management and environmental transformation [START_REF] Carter | Concepts of soil quality and their significance[END_REF]Seybold el al., 2001;[START_REF] Erkossa | Indexing soil quality: a new paradigm in soil science research[END_REF].

In our research, particular soil properties were chosen as the potential indicators according to different agricultural practices.

II.1 Physical indicators

Bulk density, water retention and transfer parameters and structural stability were chosen as basic physical soil characteristics and to study the effects of irrigation.

Soil bulk density (and porosity) varies according to soil texture, structure, and organic matter content, but within a given soil type, it can be used to monitor degree of soil compaction and puddling. Changes in bulk density affect other properties and processes that influence water and oxygen supply [START_REF] Schoenholtz | A review of chemical and physical properties as indicators of forest soil quality: challenges and opportunities[END_REF].

Water soil and transfer parameters are universally important for monitoring all soil functions. Available water holding capacity and saturated hydraulic conductivity are the two most frequently found in minimum data set (MDS) of physical soil quality indicators. Available water holding capacity measures the relative capacity of a soil to supply water and saturated hydraulic conductivity is both an indicator of drainage rate and water/air balance in soil [START_REF] Schoenholtz | A review of chemical and physical properties as indicators of forest soil quality: challenges and opportunities[END_REF].

Aggregate stability describes the ability of the soil to retain its arrangement of solid and void space when exposed to different stress [START_REF] Kay | Rates of change of soil structure under different cropping systems[END_REF]. Structural stability of soil is an essential parameter, influencing many soil physical properties such as water filtration and water-air ratio, but also erodibility, biological activity and plant growth [START_REF] Lynch | Microorganisms and structural stability-Advances in soil sciences[END_REF]. Soil structure as such is not a plant-growth factor, but it influences practically all plant-growth factors: it determines the depth that roots can penetrate, the amount of water that can be stored in the soil (soil water distribution, movement and retention), availability of plant nutrients (nutrient recycling), aeration, movement of soil fauna and microbial activity [START_REF] Hermawan | Structural changes in a silt loam under long-term conventional or minimum tillage[END_REF]Langemaack, 1999;[START_REF] Rampazzo | Assessment of soil structure parameters and functions in agricultural soils[END_REF][START_REF] Pardo | Relationships between soil structure, root distribution and water uptake of chick-pea (Cicer arietinum). Plant growth and water distribution[END_REF].

Stability characteristics are generally specific for a structural form and the type of stress being applied. A measure of aggregate stability could serve as a surrogate for soil structure, which is critical for development of root systems [START_REF] Kay | Structural aspects of soil quality[END_REF]. To evaluate the impact of management practices on the soil environment it is necessary to quantify the modifications to the soil structure [START_REF] Danielson | Methods of Soil Analysis. Part 1. Physical and Mineralogical Methods[END_REF]. Since crop management systems generally have a strong influence on soil structural characteristics, aggregate stability is considered as a key indicator to assess soil structure [START_REF] Six | Soil structure and soil organic matter: II. A normalized stability index and the effect of mineralogy[END_REF] and also soil quality [START_REF] Albiach | Organic matter components and aggregate stability after the application of different amendment to a horticultural soil[END_REF]. The decline in soil structure is increasingly seen as a form of soil degradation [START_REF] Chan | Sequestration of carbon and changes in soil quality under conservation tillage on light-textured soils in Australia: a review[END_REF] and it is often related to land use and soil/crop management practices.

II.2 Chemical indicators

Among chemical indicators for soil quality, soil reaction (pH) is obviously important in the case of liming. This basic factor is known to influence nutrient availability and microbiological activity.

Soil organic matter (SOM) is one of the most important parameter of soil quality for both scientists and farmers [START_REF] Romig | How farmers assess soil health and quality (Special Issue on Soil Quality)[END_REF]. Soil organic matter is a nutrient sink and source, enhances soil physical and chemical properties, and promotes biological activity [START_REF] Doran | Defining Soil Quality for a sustainable Environment[END_REF][START_REF] Gregorich | Towards a minimum data set to assess soil organic matter quality in agricultural soils[END_REF]. The content of soil organic matter changes very slowly and many years are generally required to detect changes resulting from disturbance [START_REF] Kandeler | Microbial soil monitoringproposal for an inventory of soils[END_REF]. It is well known that cultivation of the natural land resources induces SOM losses, which in turn directly affects the soil chemical, physical, and biological properties, and finally resulting in loss of crop production capacity [START_REF] Stevenson | Cycles of Soil[END_REF]. Soil organic carbon and total nitrogen are arguably the most significant single indicators of soil quality and productivity [START_REF] Larson | Conservation and enhancement of soil quality. -In: Evaluation for Sustainable Land Management in the Developing World[END_REF]National Research Council, 1993;[START_REF] Cannell | Trends in tillage practices in relation to sustainable crop production with special reference to temperate climates[END_REF].

II.3 Microbiological indicators

Soil organic matter (SOM) levels may vary within years, whilst active SOM-fractions like macro-and light fraction-organic matter, soil microbial biomass and microbial functions may change within shorter periods of time [START_REF] Smith | Meeting Europe"s climate change commitments: quantitative estimates of the potential for carbon mitigation by agriculture[END_REF]. Soil microorganisms have been shown to be potentially useful (early and sensitive) indicators of soil health, because they respond to soil management in time scales (month/years) that are relevant to land management [START_REF] Torsvik | Beyond the biomass: Composition and functional analysis of soil microbial communities[END_REF][START_REF] Hewitt | Setting soil quality standards for C contents of New Zealand soils[END_REF][START_REF] Sparling | Soil quality and soil health[END_REF][START_REF] Pankhurst | Biological indicators of soil health[END_REF][START_REF] Kandeler | Microbial soil monitoringproposal for an inventory of soils[END_REF]. Soil microbiota, existing in extremely high density and diversity, rapidly modify the energetic performance and activity rates to changing environmental conditions [START_REF] Schloter | Indicators for evaluating soil quality. -Agriculture[END_REF]. Some biological measurements (such as enzymatic activities) are not useful measures of soil quality because they are too much affected by both seasonal and spatial variations [START_REF] Nannipieri | The potential use of enzymes as indicators of productivity, sustainability and pollution[END_REF]. National programs for monitoring soil quality are now generally based on microbial biomass and respiration measurements and are sometimes extended also to nitrogen mineralization, microbial diversity and functional groups of soil fauna [START_REF] Bloem | Application of microbiological indicators in ecological approaches to monitor soil quality. -Agriculture[END_REF]. One of the major difficulties in the use of soil organisms per se, or of soil processes mediated by soil organisms, as indicators of soil health has been methodological: what to measure, how and when to measure it, and how to interpret changes in term of soil function [START_REF] Visser | Soil biological criteria as indicators of soil quality: soil microorganisms[END_REF][START_REF] Pankhurst | Biological indicators of soil health[END_REF][START_REF] Kandeler | Microbial soil monitoringproposal for an inventory of soils[END_REF][START_REF] Sparling | Soil microbial biomass, activity and nutrient cycling as indicators of soil health[END_REF].

Despite their small volume in soil (<0.5 %), microorganisms represent a very important component of soil organic matter [START_REF] Paul | Soil microbiology and biochemistry[END_REF][START_REF] Sylvia | Principles and Applications of Soil Microbiology[END_REF]. Soil microorganisms are involved in many biochemical processes and particularly C turnover [START_REF] Buckley | The structure of microbial communities in soil: patterns of microbial distribution their dynamic nature and the lasting impact of cultivation[END_REF]. They have an important role in soil fertility (especially decomposition of organic matter and recycling nutrients for plants) and decontamination of soils, especially degradation or bioaccumulation of toxic residues [START_REF] Soulas | Perspectives and limitations in a assessing side-effects of pesticides on the soil microflora[END_REF]. They also form symbiotic associations with roots, facilitating nitrogen fixation or phosphate uptake. They act as antagonists to pathogens, influence the weathering and solubilization of minerals [START_REF] Silver | Interactions of soil minerals with natural organics and microbes[END_REF] and contribute to soil structural stability [START_REF] Emerson | Organo-mineral Complexes in Relation to Soil Aggregation and Structure[END_REF]. Thereby, soil microorganisms and biological activity also affect water holding capacity, infiltration rate, crusting, erodibility, and susceptibility to compaction [START_REF] Elliot | The Effects of Forest Management on Erosion and Soil Productivity[END_REF]. These services are not only essential to the functioning of natural ecosystems, but also constitute an important resource for sustainable agricultural systems. Thus soil quality (or soil health) evaluations need to focus not only on chemical (fertility) considerations, but on the dynamic soil conditions as well. This supposes to consider a combination of physical, biological and chemical characteristics, which are directly affected by recent and current land use decisions and practices.

The soil microbial biomass can be defined as organisms living in soils that are generally smaller than approximately 10µm. Most attention is given to fungi and bacteria and they are generally dominating within the biomass. These two groups of microbes are the most important with reference to energy flow and nutrient transfer in terrestrial ecosystems [START_REF] Richards | The microbiology of Terrestrial ecosystems[END_REF]. It has been suggested that the microbial biomass content is an integrative signal of the microbial significance in soils because it is one of the few fractions in soil organic matter that is biologically meaningful, sensitive to management or pollution and finally measurable (Jenkinson & Powlson, 1996;Powlson, 1997). However, it must be also realized that between different soil samples different biomass may occur without direct correlation to soil quality [START_REF] Martens | Current methods for measuring microbial biomass in soil: potentials and limitations[END_REF][START_REF] Dilly | Ratios between estimates of microbial biomass content and microbial activity in soil[END_REF]. Although microbial biomass is generally acknowledged to represent only a very small proportion of total carbon in the soil (0.1-5%), it is characterised by its rapid turnover compared to the other components of organic matter [START_REF] Chaussod | Size and turnover of the microbial biomass in agricultural soils: laboratory and field measurements[END_REF].

Soil microbial respiration, measured through carbon dioxide production is a direct indicator of microbial activity and indirectly reflects the bio-availability of organic matter [START_REF] Parkin | Field and laboratory tests of soil respiration[END_REF][START_REF] Gomez | Changes in some soil properties in a Vertic Argiudoll under shortterm conservation tillage[END_REF]. Soil microbial activity leads to the liberation of nutrients available for plants but also to the mineralization or mobilization of pollutants and xenobiotics. Thus microbial activity is of crucial importance in biogeochemical cycling. Microbial activities are mostly regulated by nutritional conditions, temperature, water availability, pH and oxygen supply [START_REF] Schloter | Indicators for evaluating soil quality. -Agriculture[END_REF]. Soil pathogens. Microbial pathogens are widespread in the natural environment and diffuse pathogen pollution is chronic in rural environments. Soils and sediments are identified as having a critical role as transport pathways and reservoirs of pathogenic organisms. Despite this, important gaps remain in our knowledge of pathogens interactions with physically and biogeochemically heterogeneous soils environments. In particular, nonlinear and dynamic drivers of soil pathogen interaction and pathogen transport are under-researched because soils are complex and subsurface environments difficult to study (Centre for Sustainable Water Management, 2007Management, -2008)).

Pathogens that have the potential to infect humans can be divided into the categories of bacteria, protozoans, and viruses. Difficulties and expenses involved in the testing for specific pathogens, however, have generally led to the use of indicator organisms of enteric origin to estimate the persistence and fate of enteric pathogens in the environment [START_REF] Crane | Die-off of faecal indicator organisms following land application of poultry manure[END_REF]. Faecal coliforms (FC) are the most commonly used indicator organisms. Escherichia coli are the most common FC and although most E. coli strains are non-pathogenic, some strains, such as E. coli O157:H7, pose a serious health risk to humans. Infectious viruses found in water systems include Enterovirus, Rotavius, Hepatitis A, and Retrovirus (USEPA, 2001).

II.4 Soil quality index (SQI)

Assessment of complex soil quality and health requires a minimum data set of physical, chemical and biological parameters [START_REF] Gregorich | Towards a minimum data set to assess soil organic matter quality in agricultural soils[END_REF][START_REF] Doran | Defining and assessing soil health and sustainable productivity[END_REF] which need to be aggregated to provide an overall index of soil quality [START_REF] Burns | Defining soil quality[END_REF]. Comparison of individual indicators against reference sites is one way of assessing soil quality [START_REF] Bucher | Soil quality characterisation and remediation in relation to soil management[END_REF][START_REF] Carey | Comparison of soil quality and nutrient budget between organic and conventional kiwifruit orchards. -Agriculture[END_REF][START_REF] Nelson | Assessment of changes in soil health throughout organic potato rotation sequences, -Agriculture[END_REF], but individual indicators are often interdependent or may show functional redundancy [START_REF] Hunt | Modelling the effects of loss of soil biodiversity on ecosystem function[END_REF], so combining them meaningfully into a single index may enhance the assessment [START_REF] Bucher | Soil quality characterisation and remediation in relation to soil management[END_REF]Andrews et al., 2002). The values of the selected indicators need to be converted into scores before they are integrated into an index. This requires establishment of a functional relationship between the soil function in question and the indicators [START_REF] Erkossa | Indexing soil quality: a new paradigm in soil science research[END_REF].

III. Agricultural practices and their impact on soil quality

Soil is under pressure and its quality is suspected to decrease. The European Commission (2002) recognized soil degradation in Europe as a serious problem which is driven by human activities such as inappropriate agricultural practices, urban and industrial sprawl, industrial activities, construction, and tourism. Alteration of soil characteristics by anthropogenic impact changes functional capacities of the soil. Agricultural technologies and current practices like monocropping, residue management, mineral fertilization, overuse of pesticides, heavy agricultural machinery, inadequate management practices of soil and irrigation, can significantly affect soil quality by changing physical, chemical, and biological properties [START_REF] Fauci | Microbial biomass as an indicator of soil quality: effects of long-term management and recent soil amendments[END_REF]. Long-term human impact (e.g. sealing), as well as short-term soil management (e.g. irrigation) modifies material and energy flows. Erosion, a decline in organic matter content and biodiversity, contamination, sealing, compaction, salinization, and landslides were identified as the main soil threats (Andrews and Carroll, 2002;[START_REF] European Commission | Towards a Thematic Strategy for Soil Protection. -Communication from the commission to the council, the European Parliament, the Economic and Social Committee and the Committee of the Regions[END_REF]. Conventional horticultural cropping, due to continuous soil removal and intensive use of pesticides and fertilizers, is the main activity leading to deterioration of soil physical, chemical and biological properties [START_REF] Albiach | Microbial biomass content and enzymatic activities after the application of organic amendments to a horticultural soil[END_REF]. These modifications result in transformation of the soil processes to smaller or greater extent. When these processes are traceable, controllable, soil-use and soil quality remains sustainable on the long run (Toth, 2008). It is important to be aware that soil is a finite and non-renewable resource, because regeneration of soil through chemical and biological weathering of underlying rock requires geological time [START_REF] Huber | Proposal for a European soil monitoring and assessment framework[END_REF].

In our study, some agricultural practices are involved in alteration of soil properties in different ways and levels. Preliminary mechanical interventions on soils such as terracing, land levelling and deep ploughing are the roughest and they change soil profiles from inherent to anthropogenic. These changes are leading to major landscape modifications and land degradation [START_REF] Borselli | Soil erosion in Europe[END_REF]. In addition, new management techniques with more intensive production are used after the abandonment of traditional practices [START_REF] García-Ruiz | Land-use changes and sustainable development in mountain areas: a case study in the Spanish Pyrenees[END_REF][START_REF] Zalidis | Impacts of agricultural practices on soil and water quality in the Mediterranean region and proposed assessment methodology. -Agriculture[END_REF]. Heavy machines such as bulldozers are being used for large scale soil movements in order to create new terracing systems for vineyards and orchards. These movements are not always controlled by law or technical guidelines and are determined by the needs of the owner or the person on charge of the machinery. These works modify the soil surface characteristics, which influence the infiltration properties at the surface [START_REF] Poesen | The hydrological response of soil surfaces to rainfall as affected by cover, position and rock fragments in the top layer[END_REF]Léonard and Andrieux, 1998;[START_REF] Malet | Soil surface characteristics influence on infiltration in black marls: application to the Super-Sauze earthflow (southern Alps, France)[END_REF] and interact with other geomorphologic processes such as erosion [START_REF] Lundekvam | Agricultural policies in Norway and effects on soil erosion[END_REF] and mass movements, mainly during extreme precipitation events [START_REF] Abreu | Evaluación del efecto de las propiedades hidrológicas y sistema de manejo sobre la susceptibilidad a erosión superficial y en masa en suelos pedregosos con viña del Priorato[END_REF]. The spatial variability created by all these operations leads to heterogeneous infiltration and runoff responses on hill-slopes. The soil redistribution also modifies the soil slope stability and the stability of the terraces, increasing the risk of surface mass movements. Some studies have pointed out the spatial variability of soil properties along hill-slopes [START_REF] Agbenin | Soil properties and their variations on two contiguous hillslopes in Northeast Brazil[END_REF][START_REF] Bartoli | Spatial variability of topsoil characteristics within one silty soil type. Effects on clay migration[END_REF] and with the slope degree [START_REF] Janeau | Soil crusting and infiltration on steep slopes in northern Thailand[END_REF].

III.1 Irrigation

Irrigation is one of the most common agricultural practices in orchards and its positive effect on crop production is well known. The benefits of irrigation may include: better and improved crop (apple) quality, earlier crop production, greater yields, efficient nutrient distribution, less plant stress and reduced yield variability [START_REF] Cetin | Economics of drip irrigation for apple (Malus domestica) orchards in Turkey[END_REF]. Although irrigated agriculture has some benefits such as yield increase (Bilgehan, 1998), it brings about some problems such as increased drainage rates, salinisation-alkalinization and degradation of soil structure (Çullu et al., 2002). Irrigation is directly linked with soil water conditions what could potentially affect soil structure and thus soil water-air ratio, plant nutrition, soil microbial biomass and activity. Inappropriate production technologies have resulted in soil quality deterioration, leading to soil organic matter losses and structure degradation, affecting water, air and nutrient flows, and consequently plant growth [START_REF] Golchin | The effects of cultivation on the composition of organic matter and structural stability of soils[END_REF]. Other externalities such as crusting, runoff, surface-and groundwater pollution and increased CO 2 emissions are also influenced by irrigation. Species biodiversity can also be affected by management practices: generally high-input agricultural practices decrease biodiversity [START_REF] Munyanziza | Agricultural intensification, soil biodiversity and agro-system function in the tropics: the role of mycorrhiza in crops and trees[END_REF][START_REF] Lupwayi | Bacterial diversity in water-stable aggregates of soils under conventional and zero tillage management[END_REF]. The effects of freshwater irrigation on soil are primarily physical, including increased drainage and nutrient transport. Wastewater irrigation can have more significant chemical and biological effects on soil properties. Among the potential risks associated with irrigation with waste treated water is degradation of soil structure, e.g. aggregate stability deterioration, a decrease in soil hydraulic conductivity, surface sealing, runoff and soil erosion problems, soil compaction, and a decrease in soil aeration [START_REF] Bhardwaj | Irrigation with treated wastewater under two different irrigation methods: Effects on hydraulic conductivity of a clay soil[END_REF]. In addition to the impact of irrigation heterogeneity on the distribution of percolation in the field, it is often believed that intensive irrigation leads to rapid movement of nitrate below the root zone [START_REF] Endelman | Nitrate and chloride movement in the plainfield loamy sand under extensive irrigation[END_REF] since nitrate is carried down through the profile with the percolating water.

It can be concluded that, depending on various parameters such as water quality, soil, agricultural techniques, fertilization and other chemical treatments, crop and climate, irrigation may sometimes severely damage the soil [START_REF] Miller | Soils in Our Environment -7th edition[END_REF][START_REF] Tedeschi | Effects of irrigation with saline waters al different concentration, on soil physical and chemical characteristics[END_REF]. The initial increase in crop yields becomes unsustainable, and in some circumstances severe chemical, physical, and biological fertility problems appear [START_REF] Sun | Evaluation of spatial and temporal changes of soil quality based on geostatistical analysis in the hill region of subtropical China[END_REF], which can eventually compromise the agricultural activity itself [START_REF] Porta | Edafologia para la agricultura y el medio ambiente[END_REF]. The question is whether irrigation is capable of continuing the high level of agricultural production in the longer term without damaging the environment [START_REF] Pereira | Research Agenda on Sustainability of Water Resource Utilization in Agriculture[END_REF]. There are several examples of large areas in the world that formerly were very productive and now are almost abandoned [START_REF] Nunes | Changes in selected soil properties caused by 30 years of continuous irrigation under Mediterranean conditions[END_REF].

The primary sustainability goal for soil is the maintenance of productivity. Irrigation should be managed so that it has minimal adverse effects on the quality of the soil. This will ensure that the soil is healthy and remains productive in years to come. Proper management of irrigation water and wastewater as fertiliser can result in enhanced productivity. By using the correct indicators of soil productivity, the effects of irrigation can be gauged, and thus optimised. Soil productivity is affected directly and indirectly by the type of crop, management practices and soil quality, which in turn is affected by moisture, pH, organic matter, heavy metal content etc. Many of these soil characteristics are interdependentchanges in one characteristic result in changes in another. This means that monitoring a subset should highlight any changes in soil productivity. The effect of some agricultural practices such as irrigation on soil structure will depend both on the soil natural properties (particle-size distribution, organic matter content, etc.) and the intensity of agricultural practices [START_REF] Virto | Pore size distribution in relation to soil physical properties in two irrigated semiarid Mediterranean soils as affected by management[END_REF].

Irrigation with wastewater raises, however, sanitary problems: risk of viral and bacterial infection both for farmers and crops as well as other problems due to the presence of toxic substances. Many studies have been conducted to point out the effects of the biological depuration process on the microbiological quality of these waters and on crop pollution by pathogens [START_REF] Wolter | Harnessing water to feed a hungry world[END_REF].

It is very important to estimate the benefit of irrigation, based on appropriate soil analysis, before building an irrigation system, so as to be able to monitor the effects of irrigation on soil properties, as long as irrigation is used. For adequate water management, the proper use of these irrigation systems is important as well to avoid soil degradation and water contamination. The irrigation water should be regularly monitored chemically and biologically. The sanitary aspect of irrigation water in food safety should not be underestimated: there might be a possibility of crop pollution via irrigating water. Recent environmental investigations indicated pollution of surface or underground irrigation water with several faecal pathogens, which can also contaminate the apple harvest and have potential effects on public health. To analyse irrigation water quality on presence of pesticide, metals, salts or even pathogens, is rather an exception than a rule in Slovenia. It also has to be kept in mind that improper irrigation can cause severe damages to the environment [START_REF] Miller | Soils in Our Environment -7th edition[END_REF][START_REF] Tedeschi | Effects of irrigation with saline waters al different concentration, on soil physical and chemical characteristics[END_REF].

In general, irrigation systems in Slovenia are technically more or less well prepared (Slovenian Irrigation Project, 1998), but not enough attention is devoted to soil conditions (before, during and after irrigation). Fruit or vegetable producers should not only focus on yields (here the benefit of irrigation is already well known), but also be aware of the irrigation consequences in soil conditions. In northern-east Slovenia, many orchards lay on hilly terrains, so technical specificity on different slopes and possibility of erosion should be take into consideration. Under the same weather conditions and very heterogeneous parent material, different soils will not react in the same way, either chemically or physically. According to specific physical, chemical and biological properties of each soil type, irrigation can have many advantages and also disadvantages. So far, in Slovenia there is still no serious study on irrigation effects on soil properties, especially soil microflora and soil structure.

III.2. Organic amendments

Application of organic fertilizers is linked to soil organic carbon and nitrogen pools, which consequently change microbial parameters and plant nutrition.

Maintenance of soil organic matter is important for the long-term productivity of agroecosystems. Soil application of organic amendments is a management strategy to counteract the progressive loss of organic matter [START_REF] Marinari | Influence of organic and mineral fertilisers on soil biological and physical properties[END_REF][START_REF] Tejada | Application of a green manure and green manure composted with beet vinasse on soil restoration: effects on soil properties[END_REF]. The addition of organic amendments may improve soil physico-chemical, biochemical and microbiological properties involved in biogeochemical cycles and thus positively influences plant productivity parameters. The organic amendments are a source of slow-releasing nutrients and available energy for soil microorganisms (Gomez et al., 2006). Among the main benefits attributed to the use of organic amendments are an improved soil aggregation and reduced bulk density, a greater water holding capacity, stabilization of pH, an increased CEC [START_REF] Sasal | Efecto de diferentes enmiendas sobre algunas propiedades edáficas, en sistemas de producción hortícola del centro norte de la región pampeana[END_REF][START_REF] Tejada | Application of a green manure and green manure composted with beet vinasse on soil restoration: effects on soil properties[END_REF]. Less nutrient potential loss and particularly a reduction in the loss of nitrate are also quoted as positive effects of organic farming. As this could also promote plant health, it seems possible to obtain equivalent or even higher yields in organic production than with conventional farming [START_REF] Bulluck | Organic and synthetic fertility amendments influence soil microbial, physical and chemical properties on organic and conventional farms[END_REF][START_REF] Courtney | Soil quality and barley growth as influenced by the land application of two compost types[END_REF].

Swiss researchers [START_REF] Fließbach | Soil organic matter and biological soil quality indicators after 21 years of organic and conventional farming. -Agriculture[END_REF] concluded that organic farming with composted manure is the only agricultural practice that limits the decrease of carbon content in the soil. They show that organic farming is the best agricultural practice for sustainable land management, in particular through the enhancement of soil microbial activity, leading to increased mineral exchange between plants and soil. The use of amendments has been reported previously to increase soil organic matter, provide nutrients and improve microbial activity [START_REF] Lee | Effect of food waste compost on microbial population, soil enzyme activity and lettuce growth[END_REF]. The results are conditioned by the composition of amendments, the rate of application and the soil type [START_REF] Albiach | Organic matter components and aggregate stability after the application of different amendment to a horticultural soil[END_REF][START_REF] Tejada | Effects of the application of a compost originating from crushed cotton gin residues on wheat yield under dryland conditions[END_REF]. Furthermore, as soils are the basis of food production, preserving their quality with manure and low chemical use is essential for sustainable land management, even if these farming systems are not the most productive.

Less understood, however, are the effects of organic amendments on soil food webs, which contain the biotic assemblages responsible for decomposition and generation of soluble nutrients for plant uptake. Soil food webs also contain parasitic organisms, such as plantparasitic nematodes, whose densities are influenced by the presence of host plants, the soil environment, and regulation by predators and pathogens (all factors that are potentially influenced by organic amendments). Maximizing the efficacy of organic amendments towards improving soil health requires an understanding of how this practice affects the entire soil food web (beneficial and pathogenic/parasitic components), and how these effects are mitigated by other agricultural practices, such as tillage. However, tillage can also be used to incorporate amendments into the soil, and therefore should expand their effect into deeper soil layers [START_REF] Treonis | Effects of organic amendment and tillage on soil microorganisms and microfauna[END_REF]. Organic fruit production in Slovenia has steadily increased in recent years due to the excellent returns for growers. In 2011, almost 3 % of Slovene farmers were registered as organic producers. Slovenia still has convenient natural conditions for organic farming; so small farmers in this trend see a good or even the only solution for surviving (mostly in combination with so called "eco-tourism"). Organic farming in Slovenia is a part of Agro-environmental programme. Slovenian farmers are supported by The Institute for Sustainable Development, they are well organised in their own union and they have their own trademark ("Biodar").

Offer of organic products in Slovenia still does not follow the demand, consequently resulting in prices which are 20-40 % higher, on average, compared with conventional agricultural products. Organic products are mostly sold on special organic markets or on farms, as a part of tourist offer. Most people see organic food as something pure and healthy, but there is also another point of view, which is less known: some consumers have doubts concerning about food safety in organic production, because soils which have received material (like organic fertilisers and irrigation water, as in our case), can be potential pathogen sources. This view of food safety linked with organic production is very interesting and requires further studies, because it can also help people to be acquainted with healthy nourishment.

III.3 Liming

Liming is a traditional agricultural practice to counteract soil acidification and improving calcium and magnesium supply, with effects on crops and soil quality (including physical and biological aspects). In spite of the extended lime application, the investigation of liming effects on organic matter remained restricted to C content, mass ratio of carbon to nitrogen (C/N ratio) and carbon storage [START_REF] Derome | Forest living on Mineral Soils. Results of Finnish experiments[END_REF][START_REF] Persson | Pools and fluxes of carbon and nitrogen in 40year-old forest liming experiments in Southern Sweden[END_REF]. The following observations gave rise to the expectation that liming may also influence the chemical composition of soil organic matter (SOM). The C/N ratio of the organic surface layer material usually decrease [START_REF] Belkacem | Consequences of liming and gypsum topdressing on nitrogen and carbon dynamics in acid forest soils with different humus forms[END_REF][START_REF] Marschner | The effect of liming on quantity and chemical composition of soil organic matter in a pine forest in Berlin, Germany[END_REF] after lime application. Tree growth may be inhibited [START_REF] Derome | Forest living on Mineral Soils. Results of Finnish experiments[END_REF]) by liming, presumably as a consequence of the growth stimulation of ground (weeds) vegetation [START_REF] Rodenkirchen | Evidence for a nutritional disorder of Oxalis acetosella L. on acid forest soils. I. Control situation and effects of dolomitic liming and acid irrigation[END_REF]. The soil fauna populations are usually influenced by liming and, in general, resemble that of nutrient-rich soils [START_REF] Persson | Effects of liming on soil fauna in forests. A literature review[END_REF]. Soil microbial biomass [START_REF] Smolander | Microbial biomass C and N in limed soil of Norway spruce stands[END_REF][START_REF] Badalucco | Effect of liming on some chemical, biochemical, and microbiological properties of acid soils under spruce (Picea abies L.)[END_REF], microbial activity [START_REF] Anderson | The influence of acid irrigation and liming on the soil microbial biomass in a Norway spruce (Picea abies [L.] Karst.) stand[END_REF] and the potential for nitrification and nitrate leaching [START_REF] Neale | Changes in microbial biomass and nitrogen turnover in acidic organic soils following liming[END_REF][START_REF] De Boer | -In situ net N transformations in pine, fir, and oak stands of different ages on acid sandy soil, 3 years after liming[END_REF] may increase after liming. Root growth in the organic layer may be stimulated [START_REF] Raspe | Wurzelverteilung und Mykorrhizadynamik in Abhängigkeit vom Nährelementangebot im Boden[END_REF] or inhibited [START_REF] Helmisaari | -Fine-root biomass and necromass in limed and fertilized Norway spruce (Picea abies (L.) Karst.) stands[END_REF] by liming.

IV. Research aims

Our research is dealing with two aims:

(1) the effect of irrigation on soil quality in hilly terrain, where soil water characteristics, structural stability, total soil organic content and microbial biomass are used as the main indicators for irrigation and erosion prognosis;

(2) the effect of different organic products (fertilizers) and liming on soil quality with the goal to enhance soil microbial biomass and its activity towards better plant nutrition.

In our studies, microbes play a very important role regardless of the plant production. Microbial biomass is a measure of the size of microbial population, and a large microbial population is more likely to exhibit biodiversity and pathogen suppressiveness than a reduced population. In intensive agricultural production with irrigation, microbial biomass and diversity might be threatened due to improper irrigation or even due to intensive pesticide application, what could lead to soil degradation in long term. In organic farming, the main goal with different agricultural techniques with low pesticide input is to enhance microbial activity, thus improve element recycling and soil fertility. As microorganisms respond very quickly to changes in land management [START_REF] Entry | Influence of irrigated agriculture on soil microbial diversity[END_REF], microbial biomass and basal respiration were used as potential indicators in orchard soils. In case of using irrigation water of bad quality or improper organic fertilizers, there is also a possible risk of yield pollution with pathogens via irrigation water or organic fertilizers. For this reason, irrigation and organic farming should be controlled also from microbiological point of view.

Activity of microorganisms and structural stability are directly affected by soil moisture content and there is also a close link between activity of soil micro-organisms and structural stability [START_REF] Lynch | Microorganisms and structural stability-Advances in soil sciences[END_REF][START_REF] Kostopoulou | The effect of soil water content and microbial activity on restoring the structure of a vertisol[END_REF]. For this reason, water dynamics was observed during two seasons under different water regimes. Aggregate stability of the surface soil is critical for determining the rate of infiltration of rainfall or irrigation, thereby minimising potentially erosive runoff. These investigations where accompanied by the determination of some basic physical and chemical soil characteristics such as pH, CEC, SOM and water content, and some additional parameters like structural stability. These abiotic characteristics are complementary for a better understanding of the biological and biochemical properties and support the final evaluation of soil quality [START_REF] Mäder | Soil ecology-Impact of organic and conventional agriculture on soil biota and its significance for soil fertility[END_REF][START_REF] Filip | Soil quality assessment: an ecological attempt using microbiological and biochemical procedures[END_REF].

The aim of this research was to develop an efficient methodology that combines physical, chemical, and microbiological soil parameters to evaluate the effects of agricultural practices (irrigation, organic fertilization, liming) on soil quality and the sustainability of crop production in Slovenian orchards. Both experimental locations are geologically very different according to the geological map of Maribor [START_REF] Buser | Basic geological map of SFRY[END_REF]: Gačnik is settled on young sedimentary material (Pliocene marls) and Pohorski dvor is settled on metamorphic basement rock (micaschist) (Fig. 2.3). According to different bedrock, two very different soils are developed on each location: Calcaric Cambisol on marls and Dystric Cambisol on metamorphic micaschist.

Chapter 2

Materials and methods

Gbm

Muscovitebiotite gneiss T [START_REF] Buser | Basic geological map of SFRY[END_REF].

Gačnik Pohorski dvor

The first location, Gačnik, belongs to the Eastern Alps. The bedrock exposed at Gačnik, belongs to a sedimentary basin, which took place during the period from Miocene to Pliocene. Sedimentation started at Helvetian, with clastic sediments (conglomerate). Later gravels, marls, sands and clays were deposited until Pliocene. During the Pliocene-Quaternary some deposits of gravels, sands and clays were observed, but the main sediments are marshy sediments, sandy clays, gravels and alluvial material. In Gačnik, the bedrock is Helvetian marls with remains of foraminifers, fish teeth and bones and urchins. The Helvetian period is developed on 750 m thickness. The climate in this region is moderately continental, with mean annual rainfall of 1045 mm and mean annual temperature of 9.7˚C (National Meteorological Service of Slovenia).

In the northeast of Slovenia, where the influence of the continental climate is the strongest, the greatest differences between maximal and minimal air temperatures occur. The maximum value of air temperature is usually reached in July, while the minimum value is observed in January.

Annual precipitation changes with years, but in Maribor most of the rainfall occurs in the summer time (June, July and especially in August). January and February represent months with the lowest rainfall amount. Such distribution is the consequence of the area"s geomorphology and the fact that most of the precipitation is brought by southwest winds. Snow cover is quite frequent in winter, in spite of the ever more frequent green winters. Monthly distribution of rainfall and air temperatures .

Most of field investigations were done during 2004 and 2005. For this period monthly rainfall precipitation and air temperatures for both locations are presented in Fig. 2. 4, 2.5 & 2.6, comparing to 30-year (1961-1990) According to the monthly temperatures in both experimental years, there are no big deviations compared to long-lasting climatic conditions (Fig. 2.6). In 2004, August had the highest average temperature, while the rest of summer the temperatures in 2004 were lower than in 2005.

I.2 Detailed presentation of studied sites

I.2.1 Location Gačnik

Gačnik is an experimental orchard station for fruit growing, which belongs to Agriculture and Forest Chamber of Slovenia. It is situated on a hilly terrain (10-15 % slope), 290 m above sea level. It occupies the head of an elementary watershed (10 ha) which is ended by an artificial pond used for irrigation (Fig. 2.8 & 2.9). Many fruit species are cultivated there, but apple trees (Malus Domestica Borkh.) cv. "Breaburn" were chosen for of an irrigation study. The system of apple production here is integrated with intensive production and dense plantation system, grafted on a weak rootstock (M9). The system of water supply is drip irrigation. In the study site, strong erosion processes are expected due to an important slope (15 %), trees plantation in the slope, irrigation system and bedrock (crumby marls). For these reasons, the soils are covered with natural grass. Covering soils with plants on the hilly terrain can function as anti-erosive practice, increase soil organic matter content (Andreux, 1996) and improve soil physical characteristics [START_REF] Civc | Viticulture raisonnée. Guide pratique. -Ed Association Viticole Champenoise[END_REF]. The study site consists of two parallel 100 m-length rows: the first row is irrigated (7.29) and the second one is not irrigated (7.30), each of them containing 120 trees of "Breaburn" apple cultivar. The distance between trees in each row is 0.8 m, the distance between two rows is 3 m. The surface of the studied site is about 400 m 2 . Between the rows (in inter-row), soil is covered with natural grass 2 m wide, while bare soil takes place under the tree lines as a result of herbicide treatment (in the row) (Fig. 2.11). Soil properties were observed at 3 different slope positions (upslope, midslope and downslope) on irrigated and non-irrigated rows. Altogether 6 plots were studied according to water treatment and slope. On each plot, three different soil depths (0-5, 5-15 and 15-30 cm) were investigated. The soil type is an Eutric Calcaric Cambisol [START_REF] Fao | World Reference Basis for Soil Resources[END_REF], developed on a marl bedrock. Soils are altered by human activities like deep ploughing. The soil texture is silty clayey.

I.2.1.1 Application of treatments

Irrigation

Irrigation water source is an artificial water pond, located at the bottom of the experimental station, surrounded by orchards (pond area: 1 ha, pond depth: 3.75 m). The irrigation pump is settled one meter below the water level in the middle of the pond. The distance between irrigation pond and our studied site is around 60 m. Water is collected by runoff and precipitation in this small basin; waters coming from springs and streams are excluded. The pond is alive with fish, frogs and other living organisms.

Irrigation has been practiced since 1998, when this orchard was planted. The system of irrigation is drip irrigation with individual apertures by the trees, which is able to supply a volume of water up to 2 L -1 tree -1 day (under 2-4 bar pressure). The irrigation was adjusted to precipitation, measured at the station. If the local rainfall > 2 mm per day, there is no irrigation during the next day; if the local rainfall > 5 mm per day, there is no irrigation during the next 3 days. Irrigation has usually been performed from blooming till ripping: from 0 to 70 days per year, depending on climatic conditions. No irrigation was done in 1999 and 2005 (Tab. 2.1 and Fig. 2.12). Irrigation was the most important in the year 2003, when the number of total irrigation days strongly deviated from other years. As irrigation was the common practice in this experimental orchard before 2004 (especially in 2003), we decided to choose it for our study.

There were no accurate measurements of soil water content till 2004. In 2004 and 2005, soil water potential was followed with tensiometers almost every week in the growing season (from June to September).

Fertilising and mulching

Stock fertilising with K and P was carried out in the 1999 and 2000 (according to the result of soil chemical analysis): 100 kg.ha -1 P 2 O 5 and 60 kg.ha -1 K 2 O. After the year 2000, 60 kg.ha -1 P 2 O 5 and 60 kg.ha -1 K 2 O were applied every second year.

Every year since planting, 60-70 kg.ha -1 of N was applied, only under the tree rows. Nitrogen fertilisation has been applied twice in two equivalent parts: at the end of April and at the beginning of June. The used nitrogen fertiliser was urea (granulated form). Every fifth year extra nitrogen fertilising (30-40 kg.ha -1 of N) was performed on all the area including on grass in the inter-row, to preserve the grass cover, thus to prevent erosion.

In spring, all plant residues (leaves, fruits, branches), which are collected during the season in the rows, are mechanically raked in the inter-row and mulched together with grass. Mulching between the rows was performed seven to eight times per season, usually once in March (mostly branches), twice in May and July, once in August (mostly grass) and once in October (grass and fruits). Approximate quantity of organic litter (the whole of leaves, branches and fruits) per tree is 1-1.5 kg. Because of intensive use of different types of pesticides in the experimental station, irrigation water could be contaminated by pesticide residues.

Application of pesticides

I.2.2 Location Pohorski dvor

The experimental centre of Pohorski dvor belongs to Agriculture Faculty of Maribor. The experimental site is situated on a hilly terrain (5 % slope), 340 m above sea level (Fig. 2.13).

In this experimental centre many fruit species are present, but for organic farming study apple trees (Malus Domestica Borkh.) cv. "Topaz" was chosen. The system of apple production here was organic production with dense plantation system on a weak rootstock (M9).

For a better understanding of the results, the history of agricultural interventions on this experimental field should be taken in consideration. Short history of preparing experimental field of the orchard with "Topaz" apples:

-Untill 1995, this field was cultivated with cereals (maize).

-After 3 years of resting (until 1998), the soil was shallow ploughed in 1997 before planting. -The planting of trees was done in the spring 1998. The experimental site is made of five parallel rows, each of them contains 240 trees of "Topaz" apple cultivar. The distance between trees in each row is 0.7 m, the distance between two rows being 3.5 m. The surface of the experimental plot is about 3000 m 2 (when 4 blocks are included) or 1600 m 2 (when only three blocks are included). The soil between the tree rows (inter-row) is covered with natural grass, weeds on the row being mechanically removed periodically (Fig. 2.15). This part of the orchard lies on a 5 % slope, in eastern-western exposition. Soils are heterogeneous along the slight slope (rows), thus for sampling three blocks were investigated at two depths (5-15 and 15-30 cm). Block I lies at downslope position of this gently slope (Fig. 2.14). In our experiment, two factors were considered: organic fertilizer (4 different organic products + control) and liming. Ten different treatments are performed: each organic fertiliser (+ control) with and without liming. One plot presents each combination of treatments in each block (30 plots together). Each plot includes ten trees with isolating trees between the plots. Fertiliser and lime were applied to the soil surface (10 cm). On the schema (Fig. 2.16) the treatment numbers (from 1 to 10) represent combinations of four different organic fertilizers and a control, without and with liming (1=Compo Guano without liming, 6= Compo Guano with liming, 5="absolute control" without organic fertilizer and without liming and 10=control without organic fertilizer and with liming).

I.2.2.1 Soils

The soil type is "Dystric Cambisol" [START_REF] Fao | World Reference Basis for Soil Resources[END_REF], developed on schist. The soil texture is silty loam. The main soil characteristics before the experiment are reported in Table 2.4 and 2.5.

Traces of tractor wheels

Natural grass in the row These soil analyses were used for general presentation of the soil characteristics before starting the experiment. Considering a bulk density of 1.3, the stock of N-NH 4 or N-NH 3 till 90 cm are very similar (1.3 and 1.2 kg.m -2 respectively). But the vertical concentrations in profile are very different. Ammonium nitrogen is the highest in the surface layer and it decreases with depth, while nitrate is the highest in the sub-surface layer (30-60 cm), presumable because of the leaching process.

I.2.2.2 Application of treatments

Organic fertilising

Since 2002, different organic fertilisers were applied in this field experiment. Chemical characteristics of different organic fertilisers are presented in Table 2. [START_REF]Compo guano (without liming) increased microbial mineralisation[END_REF]. In this study, 3 fertilisers with different amount of nitrogen were included: Compo Guano (11 % N), Agrovit (5 %) and Biosol (8 %). Organic fertilisers were applied every spring (in April) from 2002 to 2005, according to nutritional requirements of apple trees (60 kg N -1 ha -1 year).

From Table 2.6, Compo guano contained the highest percentage of total and mineral (ammonium) N and the other nutrients, comparing to the other products. Ammonium presented one third of total nitrogen, which could be readily nitrified by soil microbes in forms available to plants. Amounts of total phosphorous, potassium, calcium, magnesium and sulphur were also the highest. In Compo guano, soluble organic matter presented the major part of total organic matter (97.4 %), which is very important for plant nutrition (Fig. 2.17). This non-stable organic matter could be easily mineralised in the soil and enable bigger concentration of available nutrients. The other two products (Biosol and Agrovit) included much more stable organic matter, which is harder to decompose. For these reasons, Compo guano was assumed to be the most efficient organic fertiliser. In our experiment with microbial properties, only one organic fertiliser was chosen: Compo guano.

Fig. 2.17: Biochemical composition of different organic products

Tab. 2.6: Composition of the three different organic fertilizers

Liming

Liming was performed to allow better conditions for microbial decomposition of organic matter and nitrification in this acidic soil. Without suitable rising of soil pH, we could not expect a positive effect of organic fertilizers. Rising soil pH was performed slowly (by half pH unit) twice a year to avoid stress for soil microbes.

Lime material was 98 % natural grinded (120 μm) limestone (CaCO 3 ) with 1.5 % MgCO 3 , 0.02 % FeO 3 and 0.05 % Al 2 O 3 . The commercial name is Calcivit VP.

The lime requirement was calculated by an old internal system, based on potential (in 0.1 N KCl solution) and hydrolytic (in 0.5 M Ca-acetate) soil acidity. With these two data, tables with the aimed pH values allowed calculation of lime addition, expressed as t/ha CaO. Needs were properly calculated on the basis of molecular mass of CaO and CaCO 3 , considering also the purity of lime material and area of individual plots.

During our study, liming was performed twice a year, in the spring (beginning of May) and in autumn (November), three weeks before organic fertilizers application. For each period, 2 kg lime per plot (7 m 2 ) was added. Lime was mechanically incorporated within the first 10 cm of the soil. Soil sampling was always done just before lime and fertilizers application.

Application of pesticides

Pesticides were used for preventing the invasion of insects (Oleodiazinon etc.) and fungi, according to the list of permitted substances in organic farming policy (Tab. 2.7 & 2.8).

Tab. 2.7:

Overview of all applied pesticides in the year 2004.

Mechanical applications

In each growing season, 2-3 mechanical grass cuttings and mulching were done.

I.2.3 Pohorski dvor and Gačnik: similarities and differences

Both study sites have some similarities and differences. Gačnik and Pohorski dvor locations lie in the surroundings of Maribor, so the same climate was considered. This region is well known for apple production and this was reason for choosing apple culture (on the same rootstock) with high density tree planting.

On the other hand, very obvious differences were evidenced in both sites. Sites were completely different in topography, geology and soil types. The first difference is shown in topography: at Gačnik location the apple orchard lies on a hilly terrain (15 %), while at Pohorski dvor the experimental site is settled only on a light slope gradient (5 %). Another important factor, which affects soil development, is bedrock, which strongly differs from one location to another: in Gačnik marl is the basic rock, while at Pohorski dvor the micaschist was observed. Therefore, two different soil types are developed: Calcaric cambisol on marl (Gačnik location) with high soil pH, and Dystric cambisol on mica-schist with very low soil pH (Pohorski dvor location). Considering agricultural practices, there are also some important differences, which might impact soil properties. At Gačnik location, integrated apple production is performed with intensive use of pesticides, compared to organic apple production at Pohorski dvor, where application of pesticides (and other chemical substances) is strictly limited and defined. Mechanical and herbicidal treatment of soils under the trees at Gačnik location lead to bare soil (herbicide strip), while at Pohorski dvor there is a natural grass.

Finally, investigations were focused on the effect of irrigation and slope at Gačnik and the effect of organic fertilising and liming at Pohorski dvor -on soil quality. Even if microbial biomass is a common parameter measured in both locations, these two studies are quite different. According to different kinds of treatment, water supply also differs in the two experimental fields. Processing of statistical data was also different: at Gačnik only two rows of apple orchard were involved in the trial, so no real statistical significantly differences can be expected; while at Pohorski dvor the results are repeated in three blocks (statistical block system with two factors: organic fertiliser and lime).

The main idea was to study two different treatments with two completely different soil types to find the most appropriate solution of applied agrotechnical techniques on soil quality. At Gačnik location the main target was studying the effect of slope and irrigation on soil erosion (structural stability according to soil organic matter). At Pohorski dvor, the possibility of enhancing microbial biomass (and indirectly mineralization process) with different combinations of organic fertiliser and liming was focused on.

II. Methods

II.1 Soil and water sampling

Soil sampling was performed in different ways, according to our purpose. The list of analysed soil and water parameters is presented below.

Physical analysis:

- More details about sampling are found in Annexes 1, 2 & 3.

Methods of soil sampling depend on the type of further analysis. For some physical analyses we need to preserve total soil volume and soil samples have to be undisturbed, while for chemical analysis and most of microbial analyses classical sampling with auger or shovel is recommended.

In the same period we took soil samples for special microbiological analysis (especially pathogens) we also sampled irrigation water from different positions of transporting (Tab. 2.10). Water samples were taken from the middle of the pond (where the fixed pump is settled one meter bellow the water level) and from the pipes at different points along the slope. We excluded the upslope, because we found that in pipes there was not enough pressure for pushing irrigation water to this point and overcome slope effect. Water samples were carried in plastic containers or plastic bottles, and stored in cooling box at 4 °C till analysis.

Tab. 2.10: Schedule of water sampling and analysis in Gačnik in 2007. Samples were taken with an auger from different soil depths to perform chemical and some basic soil microbial analysis (i.e. microbial biomass, carbon mineralization). For certain physical analyses (like structural stability, clod porosity and organic matter size fractionation), soil samples were taken by using small shovel, trying not to disturb soil structure or aggregates too much. Mostly, the soil samples were taken in the middle position of each row, in the line between trees (except for comparing the sunny and shady sides of each row, then soils were sampled from both sides of the herbicide strip, not in the middle). Usually almost ten replicates were carefully mixed to obtain one representative sample (0.5-1.0 kg) (except samples taken from the soil profiles). Soil samples were kept in plastic bags or plastic boxes and stored at 4 °C. Fresh soil samples were also collected for gravimetric water content analysis.

Prior to structural stability analysis and microbial analysis, fresh samples were sieved at 4 mm. Samples for basic microbial analysis were always taken at the beginning and at the end of vegetation season For chemical analyses dry soils were sieved at 2 mm. For some special microbiological analyses (i.e. fungi, bacteria and viruses), sampling was done with a small shovel from soil surface (0-5 cm) only and kept stored at 4°C. Bulk density was measured using 100 cm 3 metal cylinder and soil samples were taken with a hammer-driven core sampler. Sampling for bulk density was done at field capacity conditions, a few days after rainfall. For this analysis, three replications were made for each sample.

II.2 Soil and water regime characterization

II.2.1 Soil characterization

Three profiles were dug at Gačnik location in order to describe the morphological properties of irrigated to non-irrigated soils. Along the profiles and down to the bedrock, the following soil features were described: structure, texture, colour, humidity, presence of stones and earthworms, root depth and distribution, presence of carbonates and hydromorphic features. Soil samples were taken at different depths for further investigation.

In Pohorski dvor,two soil pits with auger were dug in inter-row space in blocks I and III (where tensiometers were settled). Simple description of some morphological soil properties was done like humidity, texture, structure, consistence, colour and presence of hydromorphyc features.

II.2.2 Water regime characterization

II.2.2.1 Water retention curves

Water retention curves were established at Biotechnical Faculty (Centre for Soil and Environmental Science), in Ljubljana on undisturbed soil cores sampled in the non irrigated row at 20, 40 and 80 cm depth for Gačnik location and in treatment 5 (pure control) in two blocks (I and III) at 20, 40 and 80 cm depth for Pohorski dvor location.

II.2.2.2 Tensiometers

Nine electronic tensiometers (SDEC SMS 2500 S) were located downslope at three different depths: 20, 40 and 80 cm (Fig. 2.18). Total water potential was measured in irrigated row, non-irrigated row and in the inter-row in Gačnik. In Pohorski dvor , measurements of water potential (ψ) in soils from treatment 5 (pure control), treatment 10 (lime only) and inter-row in blocks I and III were compared, . -total (volumetric method, according to ISO 10693) and active CaCO 3 (Drouineau-Galet"s method, according to NF X31-106) -organic carbon (Anne"s method, according to NF X31-109) -organic n itrogen (Kjeldahl"s method, according to ISO 11261) -C / N, by calculation, from above organic C and N contents.

-P 2 O 5 (Joret-Hebert method, according to NF X31-161) -exchangeable cation capacity (T) (according to NF X 31-130) -exch. Ca, Mg, K, Na (ammonium acetate method, according to NF X 31-108) At the Faculty of Agriculture, Department of Chemistry, Agrochemistry and Soil Science, Maribor, the following chemical analyses were performed:

-mineral nitrogen (NH 4 + and NO 3 -) (ÖNORM L 1091) -pH (electrometric method, in water according to ISO 10390) -total and active CaCO 3 (volumetric method, according to ISO 10693 and Drouineau-Galet"s method, according to NF X31-106) -soil organic matter content (Walkey Black method, by [START_REF] Nelson | Total carbon, organic carbon and organic matter[END_REF] At the Faculty of Chemistry and Chemical Engineering, Maribor, the following special chemical analyses of water were performed:

-chemical oxygen demand (COD) (SIST ISO 6060) -biochemical oxygen demand (BOD) (SIST ISO 5815) II.3.1.1 Analytical methods for determining C, N and δ 13 C in each grain size fraction These analysis were done after physical organic matter fractionation at the University of Burgundy, UFR des Sciences de la Terre et de l'Environnement, Laboratoire GéoSol. The analytical method for determining carbon (C) and nitrogen (N) was made by dry combustion method in a "Carlo Erba CNS 1500" CHN analyser. Soil organic samples were mineralised in a pure oxygen atmosphere at 1032 •C in the presence of CuO as catalyst. The released CO 2 was than purified and injected in a "VG-Isochrom Micromass" spectrometer fitted with triple-ion collector and dual inlet system. The natural abundance of stable isotope 13 C was determined on each sample and expressed in δ units (‰), by reference to the international standard PDB [START_REF] Craig | Isotopic standards for carbon and oxygen and correction factors for mass spectrometric analysis of carbon dioxide[END_REF], according to the following equation:

δ 13 C‰ = 10 3 x [( 13 C/ 12 C) sp -( 13 C/ 12 C) PDB ] / ( 13 C/ 12 C) PDB
C and N contents were determined by using sulphanilamide standard (41.84 % of C and 16.27 % of N). Calibration for δ 13 C was made by using the international graphite standard USGS24 (δ 13 C = -16.0 ± 0.1‰).

Duplicates or triplicates were done to get a precision better than ± 0.15 ‰ δ units.

II.3.2 Analytical methods of physical soil properties characterization

Analyses were performed at different sites.

At the Faculty of Agriculture, Maribor, Department of Chemistry, Agrochemistry and Soil Science:

-bulk density and total porosity of soil [START_REF] Blake | Bulk density[END_REF] -soil humidity (gravimetric water content) [START_REF] Gardner | Methods for Soil Analysis[END_REF]) At AgroSup Dijon (ex ENESAD), Équipe Milieu Physique et Environnement:

-clods porosity (AFNOR, 1993) At the University of Burgundy, UFR des Sciences de la Terre et de l'Environnement, Laboratoire GéoSol:

-structural stability [START_REF] Bartoli | Structure and self-similarity in silty and sandy soils: the fractal approach[END_REF] -organic matter size fractionation [START_REF] Bartoli | Structure and self-similarity in silty and sandy soils: the fractal approach[END_REF] -analysing of Corg, Norg and δ 13 C At the Biochemical Faculty of Ljubljana, Centre for Soil and Environmental Science:

-water retention curves [START_REF] Klute | Water retention: laboratory methods[END_REF])

II.3.2.1 Bulk density (γ b )
Soil bulk density was determined by using the core method [START_REF] Blake | Bulk density[END_REF]. Metal cores with known volume (112.3 cm 3 ; 53 mm diameter and 51 mm height) were used for collecting soil samples at different depths. For one representative sample three replication samples were taken. The soil was weighted and dried at 105 °C for 24 h. Bulk density was calculated from the ratio between mass of oven dry soil and total soil volume:

Bulk density (γ b ) [g cm -3 ] = M (dry soil) / V (total soil volume)

II.3.2.2 Gravimetric water content (W)
Gravimetric soil moisture content (W) was calculated from soil sample weights, before and after drying at 105 °C for 24 hours [START_REF] Gardner | Methods for Soil Analysis[END_REF]. It is calculated as the ratio between mass of water and mass of oven dry soil:

Gravimetric soil moisture content (W) [%] = (mass of water / mass of oven dry soil) x 100

II.3.2.3 Clods porosity

Clod" porosity was determined by using the "petroleum method" (AFNOR, 1993). In this method, Archimede principle is used for determining the total volume of the clod (pores + solid part). Archimede force is proportional to the volume of displaced liquid (petroleum in our case). For calculation of total clod" volume, information of petroleum density ( dp ) at defined temperature is needed, as well.

dp [g cm -3 ] = (Mγ p / V p ) dp = density of petroleum M p = mass of petroleum V P = volume of petroleum P Arch. = m p P Arch. = Archimedes force M p = mass of displaced petroleum P Arch. = dp * V total clod → V total clod = P Arch. / dp dc [g cm -3 ] = M dry clod / V total clod Dry clod"s samples (M dry clod ) were saturated with petroleum by immersion during 24 hours.

After saturation, clods were gently wiped with Kleenex paper to remove the excess of petroleum.

A measurement of Archimedes force was performed in a baker, filled with petroleum (Fig.

2.19

). First, only Archimedes force applied to empty net was measured and after, Archimedes force of net+clod was measured again in the baker with petroleum. The difference between two measurements represented the reaction of Archimedes force on the clod. Percentage of water stable soil aggregates was determined by the method described by [START_REF] Bartoli | Structure and self-similarity in silty and sandy soils: the fractal approach[END_REF], based on the method of [START_REF] Kemper | Aggregate stability and size distribution[END_REF].

A sample of 10 g of air dried soil ≤ 5 mm particle size was added to 250 ml distilled water in a wet sieving machine designed in the Centre de Pédologie Biologique, CNRS. Nine brass sieves (height 70 mm, diameter 60 mm, wire aperture 200 µm) were immersed in distilled water to 2 cm depth and oscillated horizontally in sinusoidal pattern with amplitude of 2 cm and frequency of 1.6 Hz (Fig. 2.20). Triplicate samples were shaken in this manner for periods of 2 and 6 hours. The aggregates remaining on the sieve were oven-dried (105 °C) and weighed (AS). Then the aggregates were crushed by hand, leaving only the sand fraction >200 µm particle size on the sieve. The sand was oven dried and weighed (S). The fraction of water stable >200 µm aggregates (A) was calculated as the difference between (AS) and (S), and expressed as a percentage of 105 °C oven-dried soil.

The percentage of water stable aggregates in water after desegregation time is calculated as a difference between total mass of oven-dried soil remaining on the sieves (aggregates + coarse sand) and coarse sand mass. Result is expressed in percentage of total initial soil: SA (%) = ((M total sieved -M coarse sand ) / M sample ) x 100 Where: SA (%) = percentage of stable soil aggregates M total sieved = soil mass remaining on the sieve after drying in oven (soil aggregates + coarse sand) M coarse sand = particles > 200 µm, which are remaining on the sieve after drying M sample = initial soil sample mass (air dried)

To get the results as exact as possible and minimise the final error, we also have to take into consideration the gravimetric water content (w) of the air-dried soil. The soil samples after drying in oven at 105 °C for 24 hours are completely dry i.e. without humidity. It is necessary to correct these masses in relation to initial moisture of soil samples: The fractionation was performed in water medium, advising the method of [START_REF] Andreux | Sur une méthode de fractionnement physique et chimique des agrégats des sols: origines possibles de la matière organique des fractions obtenues[END_REF]. Thirty grams of dried (50 °C) and sieved (0-2 mm) soils were first dispersed by mechanical shaking in 300 ml of water, during 16 h (ratio soil/water = 1/10). Size fragmentation was done by wet sieving (200 and 50 µm mesh sizes) combined with gentle horizontal circular shaking. Three fractions were obtained: the coarse sand fraction A (200-2000 µm), fine sand fraction B (50-200 µm), and the silt and clay fraction C (0-5 µm). The finest soil fraction (C) was centrifuged for 40 minutes at 9500 rpm before further drying (Beckman Avanti J25). Each fraction was dried at 105°C for 24 h prior to analysis; all fractions were ground by hand in agate mortar.

Because the soil samples contained carbonates, HCl decarbonation was performed on 1 g of sample with 200 ml of 2.0M HCl on the horizontal shaker for 2 hours. Excess of HCl was removed by washing with distilled water, recovering initial pH 6.0 in the supernatant. Centrifugation step was performed 15 mn at 10.000 rpm. Finally, the sample was dried and crushed again manually in an agate mortar before measurement. About 0.25 mg of soil powder from each sample was weighted and tightly sealed in a tin capsule for measuring Corg, Norg, and δ 13 C.

II.3.3 Analytical methods of microbiological soil and water properties

Basic microbial analyses of soils were performed at UMR "Microbiologie des Sols et de l'Environnement" INRA, Dijon, while specific microbial analyses of soils and irrigation water were performed at the University of Maribor, Faculty of Agriculture and Life Sciences, Department of Microbiology, Biochemistry, Molecular Biology and Biotechnology.

At INRA Laboratory of Dijon, further basic microbial analyses were done:

-soil microbial biomass [START_REF] Vance | An extraction method for measuring soil microbial biomass C[END_REF], modified by Chaussod et al., 1988) -carbon mineralization [START_REF] Chaussod | Mesure de la biomasse microbienne dans les sols cultivés. II -Cinétique de minéralisation de matière organique microbienne marquée au carbone 14[END_REF] -labile organic matter pool (Lemaitre et al., 1995).

At the Faculty of Agriculture in Maribor, specific microbial analyses in soils and irrigation water were performed as:

-enumeration of fungi (APHA, 1989) -enumeration of total aerobic and anaerobic bacteria (APHA, 1989) -enumeration of total Coliforms [START_REF] Clesceri | Standard Methods for examination of Water and Waste Water. -17th edn[END_REF]APHA, 1989) -enumeration of E. Coli (APHA, 1989) -detection of Hepatitis E and Rotavirus (USEPA Manual of Methods for Virology -EPA publication EPA/600/4-84/013 (R-7).

II.3.3.1 Soil microbial biomass

Soil microbial biomass was determined by using CHCl 3 fumigation-extraction method [START_REF] Vance | An extraction method for measuring soil microbial biomass C[END_REF], modified by [START_REF] Chaussod | Size and turnover of the microbial biomass in agricultural soils: laboratory and field measurements[END_REF].

Fresh soil samples were stored at 4 °C and sieved at 5 mm before analysis. For each sample, three subsamples (each with three replicates) are required:

-one sub-sample for determining gravimetric soil moisture (24 hours at 105 °C) -one non-fumigated sample (40 g oven-dry equivalent) immediately extracted with 200 ml of 0.05 N K 2 SO 4 , for soluble organic C and inorganic N measurement. On some occasions, pH of the extract was also measured.

-one fumigated sample (40 g oven-dry equivalent), for organic C measurement after K 2 SO 4 extraction as above.

Non-fumigated samples (3 replicates per soil sample) were placed in plastic bottles with 200 ml 0.05 N K 2 SO 4 , than shaken with a horizontal shaker for 45 minutes at 180 rpm. After shaking, samples were centrifuged (type Sorvall RC 26 PLUS Kendro Lab. Products) at 10 C for 10 mn at 5000 rpm. From each supernatant, two small (10 ml) sub-samples were taken: one for measuring organic C and another one for measuring inorganic N. Organic C was measured just after, but sub-samples for inorganic N were frozen (-18°C) until analysis. Before measuring organic C on the TOC analyser, two drops of orthophosphoric acid were added in each sub-sample, to remove mineral C. Defined volume (200 l) of the sub-sample was injected with a syringe into the analyser. Organic C in the supernatant was measured by persulphate-UV oxidation, using a Dohrmann DC80 analyser.

The next step was the preparation of soil samples for fumigation. Fresh samples were placed in 100-ml glass vials and put into vacuum desiccators. After pumping all the air from the desiccators, ethanol-free chloroform (150 ml) was introduced into the desiccators. Fumigation took 16 hours, a period of time enough to kill all the microbes. As a solvent, chloroform disrupts the cell walls of the microbes, releasing intracellular organic matter, which is then extractable with 25 mM K 2 SO 4 .

Further processing of fumigated samples was the same as with non-fumigated (shaking, centrifugation, pipetting, measuring Corg on TOC analyser).

After determining of total dissolved C on a TOC analyser, microbial biomass is calculated as the difference between C in the fumigated and non-fumigated samples, giving the chloroformlabile C pool (EC), which is proportional to microbial biomass C:

E C [mg C kg -1 soil] = [(C fumigated soil) -(C non fumigated soil)] Biomass C [mg C kg -1 soil] = EC / k EC
where k EC means extractable fraction of biomass, assumed to be about 0.38.

II.3.3.2 Labile organic matter pool

After removing the supernatant that contained the extractable microbial biomass (see the above protocol for microbial biomass), the residual soil was used to determine the labile organic C. It corresponds to a fraction of labile soil OM, which is mainly derived from microbial biomass and the biodegradation products of organic residues. It was extracted by autoclaving (in K 2 SO 4 25 mM solution) the pellet for 16 h at 120 °C [START_REF] Lemaître | An attempt to determine a pool of labile organic matter related to the soil microbial biomass[END_REF]. Soluble organic C was measured by a persulphate-UV oxidation procedure with a TOC analyser (Dohrmann DC80).

II.3.3.3 Carbon mineralization (respiration of soil microbes)

A medium-term (28 days) aerobic incubation was used, to determine the potential of the samples to mineralise organic C. Soil samples (40 g oven-dry equivalent, with three replications) were incubated at 28 °C in 550 ml glass flasks closed with rubber stoppers. Glass vials containing 10 ml of 0.25 M NaOH were placed in the flasks, to trap the evolved CO 2 . Three blanks (empty glass flasks, with only the NaOH trap) were prepared, to take into account the C-CO 3 already present in NaOH and the C-CO 2 in the atmosphere of the flasks. While respiring, the soil microbes produced CO 2 , which accumulated in the NaOH traps. The flasks were opened after 10 days, to replenish the atmosphere and change the NaOH traps. C-CO 2 was measured in this first set of traps by NDIR, using the Dohrmann DC80 analyser.

After 28 days of incubation, the measurement was repeated on the second set of traps. The sum of accumulated C-CO 2 in NaOH traps after 10 and 28 days of incubation represented total C mineralization or respiration rate (in mg C kg -1 dry mass) [START_REF] Chaussod | Mesure de la biomasse microbienne dans les sols cultivés. II -Cinétique de minéralisation de matière organique microbienne marquée au carbone 14[END_REF].

II.3.3.4 Enumeration of bacteria and fungi present in soil and water samples

Using the spread-plate technique and 100 µl from the serial dilutions (up to10 -6 ) of soil and water samples, plates for the determination of aerobic (APC) and anaerobic plate counts (ANAPC), fungi, total and faecal (thermo tolerant) coliforms and E. coli were prepared using selective culture media according to Standard Methods (APHA, 1989;[START_REF] Clesceri | Standard Methods for examination of Water and Waste Water. -17th edn[END_REF].

Aerobic and anaerobic bacterial plate counts were made with NA agar (Nutrient agar), and plates were incubated at 22°C for 48 hours (aerobically and anaerobically in anaerobic boxes).

For fungi counting PDA (Potato Dextrose agar) was used and plates were incubated at 22 °C for 4 days aerobically. Total and thermo tolerant coliforms counts were made on EEC agar (Hi Crome Selective agar). Total coliforms plates were incubated at 37°C, while thermo tolerant (faecal) coliforms were incubated at 44°C for 24 hours aerobically. In both types of coliform plates two typical colonies were counted: blue to dark violet colour (E. coli) and light salmon colour (the rest of coliforms). In all serial dilutions colonies between 30 to 300 colonies were counted.

The viable titer is determined by counting colonies (CFU's) per volume plated and multiplying by the dilution factor [START_REF] Madigan | Biology of Micro organisms. -9[END_REF].

Viable titer = (CFU/volume plated) x Dilution factor II.3.3.5 Detection of enteroviruses in soils and water

Isolation of enteroviruses in water

Twenty litres of irrigation water were collected in the field (Gačnik) and concentrated by a conventional filter adsorption-elution method (modified by [START_REF] Rutjes | Isolation and Detection of Enterovirus RNA from Largevolume Water samples by using Sequences-Based Amplification[END_REF]. 0.05 M magnesium chloride was added to the water sample to enable the formation of a virusmagnesium complex. By reducing the pH to 3.8 with 0.5 M HCl, these complexes adsorb to a negatively charged Millipore filter (1.2 µm, 0.65 µm, 0.45 µm, 0.22 µm, Millipore, Etten-Leur, The Netherlands). The finest filter (0.22 µm) was washed in 5M NaOH solution.

Viruses were eluted from the filter with elution buffer (pH 9.0) containing 3 % beef extract (Difco Laboratories, Detroit, MI). The typical eluate volume of 20 L of raw sewage water is approximately 50 ml. Eluates were stored at -70 °C until further use.

Isolation of enteroviruses in soil

One hundred grams of soil were simultaneously collected. The protocol for isolation of viruses was followed by USEPA Manual of Methods for Virology -EPA publication EPA/600/4-84/013 (R-7). Briefly, 100 mL of buffered 10 % beef extract was added to 100 g of soil and vessel was placed on magnetic stirrer for 30 min. reducing the pH between 3.5 and 6.0 with 0.5 M HCl was done. Further, centrifugation of mixture was performed (2500 rpm for 30 minutes at +4°C). Decanted supernatant fluid was filtrated through 0.22 µm porous negatively charge Millipore filter. Eluate was stored until assay at -70 °C.

II.3.3.6 Qualitative analysis of HEV and Rotavirus with dotblot assay

Dot Blot was performed to determine the presence of specific enteroviruses (HEV and Rotavirus) in elutes. Elutes were loaded under gravity onto the nitro-cellulose transfer membrane (Pierce, Rockford, USA) by use of Dot Blot apparatus (BioRad). Supernatant containing HEV and Rotavirus were applied to the membrane as the positive controls. The membrane was washed three times with 0.1 ml of 1X TBS (20 mmol l -1 tris and 137 mmol -1 NaCl, pH 7.6). Non-specific binding sites were blocked with blocking solution for 16 h at 4 °C. The membranes were incubated for 1 h at room temperature with primary antibodies: polyclonal rabbit anti HEV (ABcam) and goat polyclonal antiRota (ABcam) diluted in blocking solution. Following subsequent was washed three times with 1 x TTBS (each wash 10 mn under gentle shaking), membranes were incubated for additional hours at room temperature with secondary antibody: the anti-rabbit and anti-goat peroxidaseconjugated IgG (Sigma) diluted in blocking solution. Membranes were then washed three times with 1 x TTBS again and developed with Supersignal West Pico chemiluminescent substrate system (Pierce, Rockford, USA). After developing for 5 mn, the membranes were exposed to Biomax MR-1 film (Sigma-Kodak) for 10 mn with use of Sigma processing chemicals Kodak GBX developer and fixer system.

II.4 Statistical analysis

The data were statistically analysed as a split-plot design (main plots are irrigated and nonirrigated rows, subplots were slopes of the hill and soil depths) at Gačnik location and as a two factor trial (the first factor is organic fertiliser, the second factor is liming) at Pohorski dvor location. The second location has a stronger statistical basis compared to the first one, as three blocks were included in the experiment. Chapter 3

Results in Gačnik

Chapter 3: Results Gačnik

I. Soil morphology

For a better understanding of the results of our study, it is very important to describe the morphological properties of soils first and represent soils in general.

I.1 Soil profiles

To compare soil organization according to slope and the effects of irrigation, two soil profiles were described. Both soil profiles were opened from the irrigated row (across inter-row) to the non irrigated row at two slope positions: upslope and downslope position, perpendicularly to the rows (Fig. 3.2 & 3.3). Soil surface observations Some obvious differences in the soil surface were observed according to slope and sun exposure. In the upper third of the slope, brighter soil colour and development of large cracks were noticed. Presumably, brighter colour is related to lower organic matter content and cracks to drier soil conditions. According to the sun exposure, at the sunny side of the rows, thicker structural crust (3 cm) was observed (Fig. 3.4); while at the shady side, structural crust (1 cm) covered with green algae appeared (Fig 3. The upslope profile was dug till 60 cm, although boundary of marl as a weathering horizon was settled already at 40 cm (Fig 3.6 & Tab. 3.1). The soil was very dry and we noticed many vertical cracks all over the profile, which probably resulted from shrinking of the clayey structural horizon developed from marl (Fig. 3.7). These cracks enabled water and roots to move through the soil profile. Due to cracks development, surface water runoff should not be so strong and additionally aeration should be good enough in spite of high clay content. Some earthworms and fine roots were found through vertical cracks. Under 40 cm, roots were mostly growing horizontally due to lamellar structure of marl.

In the first 3 cm, the structure was granular to subangular polyedric, then polyedric up to 15 cm, below this line some individual blocks of marl appeared, contributing partly to lamellar structure. In the first 10 cm, biological activity was weak, while deeper roots density was higher till 40 cm and many earthworms" channels were noticed. In inter-row (upslope position), soils under and between the wheels were also observed. These soils were covered by grass. In all inter-row, the texture was silty clay.

In the soils between the wheels, progressive transition from fine granular structure (in the first 5 cm) via subangular polyedric structure (< 2 mm size) to fine polyedric and finally coarse polyedric structure occurred. Very abundant grass roots were observed till 5 cm. Colour: 10 YR 5/3 till 5 cm, from 5 to 15 cm 10YR 5/3, after 10YR 6/6 as a matrix with 10YR 5/3 mottles. In all inter-row, soils were fresh till 10 cm, while they became humid deeper. Biological activity was moderate, fine roots appeared in the first 5 cm, deeper lateral tree roots appeared. Weathering marl horizon appeared at 40 cm in the whole inter-row.

In soils under the wheels, in first 3 cm a lamellar structure was noticed, very well developed; lamellas were 2-5 mm thick. Lamellar structure was a consequence of the strong compaction due to tractor wheels. From 3-10 cm, fine polyedric structure appeared (< 1 cm size). Below 10 cm, coarse polyedric structure occurred. Biological activity was reduced due to compaction; till 5 cm, fine roots of grass and few earthworms channels were observed, while tree roots showed the highest density in the 10-30 cm layer. Vertical variation of colours was interpreted in terms of organic matter content. In the first few cm dark brown (10YR 3/3) was related to high organic matter content, while in 5-20 cm less organic matter was present (10YR 5/3 as a matrix and 10YR 5/4 as mottles). From 20-30 cm 10YR 6/8 colour appeared, with mottles of 10YR 5/3. From 30-40 cm, hydromorphic features with mix grey colour (2,5YR 6/2) and yellowish brown (10YR 5/8) were noticed.

Vertical crack

Block of marl

Polyedric structure

I.1.2 Downslope soil profile

At downslope position, less clay was noticed in the first 30 cm than deeper. The structure in the surface layer (till 5 cm) was very finely granulated, while deeper (till 15 cm), a mixture of granular and subangular polyedric structure was observed. Then the structure was only polyedric and size of the aggregates increased with depth, from fine between 15 to 30 cm to very coarse under 60 cm, with a correlative decrease of macroporosity as intra-aggregate pores were scarce (Fig 3.8 & Tab.3.2). Very good biological activity was noticed till 60 cm (many channels of earthworms, ants, moles and mice; roots are placed mostly horizontally, density of roots was the biggest between 10 and 30 cm). Porosity was good. A lot of fine roots inside the clods were noticed. Water content was higher under 60 cm. Bellow this line, hydromorphic features were observed (basic colour 10YR 5/4; brown spot 10 YR 5/6 and grey spot 2.5 YR 6/3).

Watching soil colour, soil in this profile was strongly mixed from 30 to 60 cm, what was noticed as a mixture of large volumes: dark brown volumes (10YR 5/4) surrounded by a lighter brown matrix (10 YR 5/6). Here more sand was observed than in the other layers. The weathered saprolithe occurred at 1m. In upper layers (till 80 cm), carbonates (around 10%) were detected, no carbonates were noticed from 80 cm till 1 m. No morphological differences were observed between IRR and NIR rows at downslope position (Fig. 3.9a &b). In the inter-row downslope, soil surface was completely covered with grass.

In the soils between the wheels (Fig. 3.10 right side), in the first 5 cm, fine granular to subangular structure (< 2 mm size of aggregates) was observed, with a gradually passage to fine polyedric structure lower, which progressively became coarser. Many grass roots were present till 5 cm. Colour: 10 YR 3/3 in first 3 cm, from 3-15 cm 10 YR 4/4 and deeper 10 YR 5/3. Under 10 cm, local faint hydromorphic features were noticed, while porosity was lower. In all inter-row soils were fresh till 10 cm and water content increased deeper.

In soils under the wheels (Fig. 3.10 left side), lamellar structure was noticed in the first 4 cm a, very well developed; lamellas were 2-5 mm size. From 3-10 cm, fine polyedric structure appeared (< 1 cm size). Below 10 cm, coarse polyedric structure began to appear (2-3 cm size). Till 10 cm, a lot of grass roots were observed, but just a few tree roots and earthworms channels were noticed here. From the soil colour, it was obvious that organic matter was higher in the first few cm (10YR 3/2) than lower (10 YR 4/4). Under 10 cm, 10YR 5/8 hydromorphic mottles appeared locally. Low porosity was observed due to strong compaction.

I.2 Comparison of soils from different water regime and slope positions

No morphological differences were observed between IRR and NIR rows at both slope positions.

Comparison of soils from the two slope positions showed that soils from upslope had less biological activity and less organic matter. Geological substratum appeared already at 60 cm or less (in the individual blocks). They were drier due to their thickness and runoff water through big vertical cracks and runoff along the slope. While downslope soils where much deeper, weathered marl saprolithe appeared at one meter. Soil layer with favourable granular structure was thicker (till 10 cm), while upslope it was only 3 cm thick. Downslope was also characterized by a large heterogeneous horizon between 30 and 60 cm depth composed by a Polyedric s.

Lamellar s.

Granular s.

mixture of large dark brown volumes embedded in a lighter brown matrix, resulting from deep ploughing.

I.3 Conclusions

1. We can conclude that this orchard soil is very anthropogenic and heterogeneous, resulting of terracing and land levelling before planting trees, and deep ploughing (60 cm). 2. According the slope position, differences in soil depth were noticeable: shallow soil upslope (40 cm) and deep soil downslope (100 cm). 3. On the surface, structural crust (1-3 cm thickness) was observed. 4. Development of structural horizons were noticed from 0 to 15 cm, as a result of shallow ploughing and present pedogenesis from previous disturbed P horizon below.

In these horizons, granular to subangular structure was noticed in upper layer, while in deeper layers compact polyedric structure occurred. 5. No differences in soil structure were noticed between IRR and NIR rows.

II. Soil water regime and quality of irrigation water II.1 Water retention curves

Water retention curves were done on NIR soil samples (control) for three depths: 20-25, 40-45 and 80-85 cm at downslope position, where tensiometers were settled. These curves were done measuring water content at 6 pressure heads: 33, 100, 200, 300, 500, 1000 and1500 kPa (Tab. 3.3 in Fig. 3.11).

Tab. 3.3: Volumetric water content (θ) and water ratio ( ) at different pressure heads. θ (cm 3 .cm -3 ) = volumetric water content; = water ratio Volumetric water content was calculated from gravimetric water content and bulk density of soils in each layer: θ (cm 3 .cm -3 ) = W (gg -1 ) * d where θ (cm 3 .cm -3 ) = volumetric water content W (g.g -1 ) = gravimetric water content (cm 3 .cm -3 ) = water ratio = V water / V solid d (g.cm -3 ) = bulk density Measured bulk density were 1.29, 1.32 and 1.39 g.cm -3 for the layers 20-25, 40-45 and 80-85 cm respectively. θ (cm 3 cm -3 ) Typical soil water retention curves (SWRC) are shown in Fig. 3.11 SWRC shows how, when a soil is dried from saturation, the water content, θ, decreases as the soil water potential, ψ, becomes more negative. Available water (AW) is defined as a difference in water content between field capacity (FC) and wilting point (WP). AW = FC -WP Wilting point (WP) = 4.2 pF (15 bar = 1500 kPa) Field capacity (FC) = 2.5 pF (0.33 bar = 33 kPa)

At FC, all three layers contained more or less the same water content (the surface and the deepest soil layers 0.5 cm 3 cm -3 and middle layer 0.53 cm 3 cm -3 ). Significant difference occurred at WP, where the deepest soil layer held 30 % less water (0.24 cm 3 .cm -3 ) comparing the middle (0.34 cm3.cm -3 ) and the surface layer (0.36 cm 3 .cm -3 ).

Available water increased with depth: 0.14, 0.19 and 0.26 cm 3 .cm -3 for 20-25, 40-45 and 80-85 cm, respectively. As seen in Tab. 3.4, textures of the different layers were silty clay. Percentage of all particle size fractions were more or less the same in the first two layers, while deeper decreasing of clay and increasing of fine silt was noticed, which could also explain the lower amount of water retained of WP and bigger amount of available water in this deeper layer. The curves for available water in the upper soil layers (20-25 cm and 40-45 cm) had more or less a similar slope pattern. Here we are dealing with fine polyedric structure with higher clay content, which explained less available water for plants.

II.2 Soil water regime in 2004 and 2005

To follow the soil water regime, measurements of water potential (ψ) from IRR, NIR rows and soils from inter-row were compared, at three soil layers: 20-25 cm, 40-45 cm and 80-85 cm during the two seasons (2004 & 2005)

II.2.1 Evolution of soil water potential along 2004 summer

Distribution of rainfall in two studied seasons is presented in Tab. 3.5. In June 2004, 175 mm of rainfall was measured, which probably enabled sufficient water for plants. In July 2004, 70 mm of rainfall was measured, while in the first two decades of August only 18 mm and in the third decade of August 52 mm of rainfall was measured. In the first decade of September 2004, only a small quantity of precipitation was measured (12 mm). Two main dry periods were noticed in the season 2004: in the middle of July and in the first half of August. If 64 rainfall was insufficient, irrigation was performed with a rate of 2 litres/day/tree. In the first dry period, 15 days of irrigation was performed (from 15 th of July till 1 st August), while in the second dry period, 10 days of irrigation was performed (from 15 th till 25 th of August). Comparing water potential curves in different soil layers, the deepest soil layer (80 cm) showed bigger variation than upper layers. Soil from the deepest soil layer (80-85 cm) had the lowest water potential comparing soils from upper layers, especially in dry periods.

Some differences occurred in pattern of water potential measurements in IRR, NIR rows and in inter-row according to dry periods. Water potential very clearly followed the rainfall distribution in all situations. Till the beginning of July, when rainfall occurred regularly, water retention measurements were very similar according to treatments and depth. In the first dry period (in the middle of July), a decrease of water potential in soils from all three layers happened simultaneously. In this period, irrigation was performed and permitted a rising of water potential in IRR row in the third decade of July, associated to a moderate rainfall. Due to water deficit in first half of August, water potential strongly decreased in the middle of August -but not simultaneously in all three layers and treatments. At this minimum peak, different reactions among soil layers were noticed: soils from surface layer reacted more rapidly to the addition of water from rainfall and from irrigation comparing to deeper layers. Mid-layer (40-45 cm) responded to irrigation with a few days delay. The deepest soil layer (80-85 cm) also responded with a few more days of delay after mid-layer. Water potential measurements in this dry period were much lower comparing to dry period in July, especially in IRR row. At the end of August, different response of water potential was observed in IRR and NIR rows: additional water from irrigation helped to raise water potential in IRR row from very low values. On both minimum peaks, IRR row had lower water potential than NIR row. This systematic observed feature may be related to a more superficial root system in the irrigated row induced by the drip irrigation as shows by [START_REF] Isberie | Interactions entre l'irrigation localisée et l'enracinement en arboriculture fruitière. -Sémin. Groupe Étud. Arbre "La racine et le système racinaire[END_REF] mentioning drier soil around the dripper.

Soil water potential pattern in soil from inter-row strongly differed from those in the rows. Till beginning of July, when rainfall occurred regularly, water potential measurements were more or less the same, but lower than in IRR and NIR rows.

In the first dry period (in the middle of July), decrease of water potential in soils from all three layers happened more or less simultaneously. In this period, only in the deepest soil layer some differences were noticed at the end of July with rising of water potential with a few days of delay. Due to rainfall deficit in the first half of August, water potential simultaneously decreased in lower layers only. In the third week of August, the strongest response to the rainfall happened in the deepest soil layer again, while in the surface layer almost no response was noticed. Delay between rainfall event and potential rising of the deepest tensiometer without any rising of the upper tensiometers means that water did not come vertically from the surface but laterally from upslope with ten or fifteen days of delay. It was hypodermic water fluxes circulating laterally above the marl saprolithe. Later, also due to lack of rainfall water, water potential in deeper soil layers began to decrease again.

The more superficial tensiometer (20-25 cm) after its decrease in the first dry period, kept the same potential at -300 hPa without rising, following the rainfall events at the end of July and the end of August. It could be related to the evapotranspiration of the grass cover in the interrow. To compare, in the NIR the potential were higher (between 100 and 200 hPa) and responded to the precipitations which could be related to: (1) a better infiltration and a lower evaporation of the bare soil in the row and (2) rainfall interception by the trees: water flow along the trunk could represent according to species between 3 to 30% of rainfall under forest [START_REF] Ulrich | Interception des pluies en forêt: facteurs déterminants. Interprétation des mesures réalisées dans le sous-réseau -CATAENAT de RENECOFOR[END_REF] The intermediate tensiometer (40-45 cm) decreased continuously from the first dry till the mid of August (-700 hPa) due to grass evapotranspiration and water uptake from tree roots. Then the potential rose following the rainfall at the end of August while the more superficial tensiometer did not react, which could be related to preferential flow along the cracks in this dry clayey soil. General shapes of water potential measurements were related to rainfall amounts. Some differences were noticed in water potential among soil layers in the rows; while in inter-row, the measurements of water potential in all three layers were almost the same.

II.2.3 Comparison summers 2004 and 2005

Comparing the two seasons (2004 and 2005), summer 2004 was much drier than 2005. In 2004, two dry periods occurred (one at end of July and another at the end of August), while in 2005 one strong dry period happened earlier (in June) and two small "dry periods" followed (in July and in September).

NIR row showed higher water potential than IRR row in both years. This is surprising, but it must be pointed out that organic matter content was generally higher in NIR treatment, with positive effect on water retention. Another possible explanation could be more developed trees in the IRR row due to more favourable water conditions what could participated to more developed root system and thus more intensive root suction (personal communication, Mr. Zadravec, The Head of experimental station: the yield of irrigated rows was higher than non irrigated one). In both seasons, the lowest water potential was measured in the deepest soil layer of IRR and NIR rows. Comparing the two seasons, a big difference occurred in patterns in soils from inter-row. In 2005, the tensiometer response of soil from inter-row was much more similar to soils from rows (IRR, NIR) than the previous season. In 2004, the obvious effect of grass water uptake was observed on the behaviour of the two first tensiometers and incidence of delayed lateral hypodermic flow for the deeper tensiometer.

Measurements of water potential in all treatments and in both seasons never reached the wilting point. According that apple trees require 70-80% of water of FC and factor 0.5 for easily available water of FC (Slovenian irrigation project, 1998), some available water deficit occurred in the season 2004 (especially in the deepest layer).

Soil matrix potential (SMP), especially in non-saline areas, is considered a better criterion for characterizing crop soil water availability than gravimetric or volumetric water content. Numerous studies using tensiometers to measure SMP and schedule irrigation have been reported [START_REF] Clark | Water requirements and crop coefficients of drip-irrigated strawberry plants[END_REF][START_REF] Shock | Irrigation criteria for drip-irrigated onions[END_REF][START_REF] Wilson | The effect of irrigation strategies during tuber initiation on marketable yield and development of common scab disease of potato in Russet Baurbank in Tasmania[END_REF].

Although the rain affected the targeted soil matrix potential readings at depth of 20 cm. temporal and spatial changes in soil water in the observed profile suggest that matrix potential at 20 cm immediately under emitter can be used as an index for scheduling drip irrigation [START_REF] Wang | Effects of soil matric potential on potato growth under drip irrigation in the North China Plain[END_REF].

II.3 Quality of irrigation water

Irrigation water was sampled from two locations: i) directly from the primary source of irrigation (i.e. irrigation pond) and ii) from irrigation pipe. The main purpose for sampling from irrigation pipe was the microbiological sanitary aspect, but it can also help to understand the chemistry of irrigated soils. For this reason, the extended chemical analysis was made for water from irrigation pond only. The results are presented in Tab. 3.6. Basic chemical parameters were measured for assessing irrigation water. Beside pH and macronutrients, electroconductivity (EC) and sodium adsorption ratio (SAR) were measured or calculated. Chemical and biochemical oxygen demand (COD and BOD) were measured for assessing pollution of irrigated water.

Tab

The pH values of irrigation water ranged between 7.8 and 8.0, lying within the normal range according to Ayers and Westcot (1985) as well as by WHO (1992), reporting that correct pH values for irrigation are between 6.4 to 8.4.

The EC value of IRR water was 0.61 mS.cm -1 . According Ayers and Westcot (1985), this value allows a classification as "no restriction for irrigation". With such an EC value, this water is convenient for irrigation according to the Official Gazette of Republic Slovenia (limit value: 2 mS.cm -1 ).

The data revealed that Ca 2+ was the dominating cation, followed by Mg 2+ and Na + ; whereas K + was the lowest. On the other hand, the main soluble anions were (in descending order): HCO - 3 > Cl -> SO 4 = . The predominance of soluble ions of Ca +2 and Mg +2 was positively reflected on the low SAR value, which was 0.43. Such low SAR value in the investigated water-pond gives none degree of restriction for irrigation of agricultural crops [START_REF] Metcaff | Wastewater Engineering Treatment and Reuse. -4 th Ed[END_REF].

Nitrate was found in appreciably high concentration (10 mg.L -1 ) compared to ammonium and nitrite (0.1 and 0.05 mg.L -1 ). The amount of nitrate is on borderline by Official Gazette of Republic Slovenia (limit value is 10 mg.L -1 ). According to [START_REF] Fao | Waste-water treatment and use in agriculture. -Rome, Italy[END_REF] and WHO (1992) guidelines, high nitrogen concentration must be avoided not only for sensitive crops but also to avoid nitrate leaching.

The concentrations of COD and BOD (180 and 100 mgL -1 ) exceeded the permissible limit for water reuse as recommended by [START_REF] Metcaff | Wastewater Engineering Treatment and Reuse. -4 th Ed[END_REF]. These high values indicate the presence of organic matter, a large part of which is easily mineralized by microorganisms [START_REF] Metcaff | Wastewater Engineering Treatment and Reuse. -4 th Ed[END_REF]. Some parameters (pH, COD, BOD) were measured also in water from the irrigation pipe. The pH was roughly the same as in the pond. However, COD and BOD levels were slightly higher in irrigation pipe than in the pond.

III. Physico-chemical soil characteristics III.1 General soil characteristics

III.1.1 Results

Complete chemical analyses, including particle-size distribution were done in September 2005. General soil properties for comparing irrigated (IRR) and non irrigated (NIR) soils are presented in Tab. 3.7a &b & c, according to slope position.

The soil texture is silty clay in general. In both water treatments, the percentage of clay in the surface layer (0-30 cm) is more than 40%. Clay and silt fractions represent more or less an equal percentage of soil particles, while sand fraction represents only a few percents (from 1.0-4.9%).

Particle size distribution did not vary largely according to depth, slope or treatment (Fig. In Fig. 3.15, general presentation of soil organic matter (SOM), C/N, total carbonates and cation exchange capacity (CEC) distributions and relations among them are described. Further, each of these parameters is more precisely described in Fig. 3 pH in water was at least 8 in all situations (from 8.0 to 8.4 %) as a result of the presence of calcium carbonates. pH increased with depth at upslope position only, while at lower positions this pattern was not noticed. No evident difference according to slope position was observed for soil pH. pH value was more or less the same in both water treatments.

3.14).

Levels of total carbonates (%CaCO 3 ) and active lime are presented in Fig. 3.16a & b. The maximum value of total CaCO 3 was recorded in NIR soils at upslope position in the deepest layer (18.8 %), while the minimum occurred in NIR soils at downslope in surface soil layer (3.6 %).

From the surface to 15-30 cm, total carbonate was slightly increasing. Upslope total carbonates were even three times higher compared to lower slope positions. A higher amount was noticed in IRR soils, especially at upslope position, while at midslope and downslope positions values were almost the same for both treatments (IRR, NIR): 5-7 % of total CaCO 3 .

In the studied soil samples, active lime represented approximately a half of the total carbonates, on average. The maximum value (8.4%) was determined at upslope position in the 5-15 cm layer of IRR treatment, while the minimum value (2.4%) was found at downslope position in the surface soil layer (0-5 cm) of NIR treatment. Similarly to the total carbonates content, active lime slightly increased with depth (till 15 cm) and towards upslope: the observed values were higher at upslope position than at midslope and downslope positions. A higher amount of active lime was noticed in IRR row. In most cases, a slight decrease of Corg was observed with depth (10-20 % of variation). Soil organic matter (SOM) increased towards downslope: at upslope position, SOM content was low compared to midslope and downslope positions. When Corg content was compared between the two studied rows (IRR, NIR), a higher amount of C org was noticed in the NIR row at upslope position (+ 40%). The difference was smaller at the midslope position, while downslope no difference was noticed. Two different patterns were noticed for C/N ratio according to depth (Fig. 3.17b): in IRR row C/N ratio decreased with soil depth while it increased in NIR row. At upslope position C/N ratios was very low especially in IRR row (3.5 -5.1) while at lower slope positions C/N ratio varied between 6.5 and 8.8. NIR row showed higher C/N ratio than IRR row, except at downslope position. According to soil depth, generally no differences were found in cation exchange capacity (CEC). CEC values were higher at lower slope positions compared to upslope. Higher CEC (including exch. Na) was recorded in NIR row.

Available phosphorus was slightly higher in the surface layer compared to deeper layers, especially in NIR row. The level of available phosphorus increased towards downslope. No evident difference in available phosphorus was noticed between IRR and NIR rows. The major part of total mineral nitrogen was present as nitrates (about 90 %), while ammonium contributed to a minor part (about 10 %).

In general, there was more total mineral nitrogen upslope. Moreover, a slight trend of decreasing Nmin down the slope was observed. Nitrates and ammonium had the same pattern as total Nmin in IRR row (the highest values upslope), while in NIR row this pattern corresponded to nitrates only. Here, the highest ammonium value was measured at downslope position.

Comparing irrigation treatments, higher amounts of total Nmin were recorded in IRR row, with a slight trend of increasing nitrate and ammonium concentrations with soil depth.

III.1.2 Discussion

According to physico-chemical parameters, the soils along the slope were very heterogeneous.

A slightly higher percentage of clay at downslope position is interpreted as the result of erosion of fine particles. This was expected because such fine particles are easily removed either horizontally by water erosion (surface water runoff) or migration by lateral downward (subsurface) movement throughout soil profile. The expected trend over a landscape is for increased fine particles on lower slope position [START_REF] Morgan | Soil Erosion and Conversation[END_REF]. However, it is important to point out that, comparing IRR and NIR rows, no difference was noticed between these two treatments.

No significant differences were observed in soil pH between IRR and NIR rows, which was in agreement with [START_REF] Nunes | Changes in selected soil properties caused by 30 years of continuous irrigation under Mediterranean conditions[END_REF], [START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF][START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF][START_REF] Zhao | -Land use change in Asia and the ecological consequences[END_REF]. Some authors reported on soil pH increase due to irrigation water [START_REF] Murray | A review of Dr Bruce Cockroft's work for Australian irrigated Horticulture[END_REF]. Irrigated agriculture sometimes uses large quantities of fertilizers, inducing secondary salinization [START_REF] Corwin | Monitoring management induced spatial-temporal changes in soil quality through soil sampling directed by apparent electrical conductivity[END_REF].

Carbonate increase with depth and higher carbonate content upslope was related to soil thickness and appearance of marl (only 60 cm below soil surface upslope), while downslope weathered saprolithe of marl did not appear before 1 m. More carbonates were observed in IRR row (0-5 cm).

Soil organic matter is considered the single most important indicator of soil quality and a major component in the assessment of soil quality [START_REF] Larson | Conservation and enhancement of soil quality. -In: Evaluation for Sustainable Land Management in the Developing World[END_REF][START_REF] Acton | Understanding soil health[END_REF][START_REF] Sikora | Assessing soil quality by testing organic matter[END_REF]. Our data exhibited great variations in soil organic carbon along the slope. At upslope position, soil was poor in SOM and it was increasing towards downslope, which could be explained partly by downward transport of organic fragments, either free or associated with fine mineral particles. These findings are in agreement with those reported by [START_REF] Hao | Effect of cropland management and slope position on soil organic carbon pool at the North application experimental watersheds[END_REF] who found a significant difference in soil organic carbon between upper and lower slope positions.

77

IRR row contained less SOM than NIR row, thus in our study irrigation was responsible for a decrease in soil organic matter. One possible hypothesis could explain this observation: due to more favourable water conditions in summer, microbial mineralization of soil OM in IRR treatment was favoured, thus decreasing SOM content. Credibility of this hypothesis will be discussed later with microbiological soil parameters. Some other authors also reported SOM increase due to IRR water [START_REF] Zhao | -Land use change in Asia and the ecological consequences[END_REF], while others did not find any effect of IRR on SOM content [START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF]. Irrigated production has also been shown to increase total nitrogen and carbon in cases where these values were low in the native condition [START_REF] Lueking | Changes in soil carbon and nitrogen due to irrigation development in Nebraska's sandhill soils[END_REF].

Two different patterns in C/N ratio occurred according to soil depth: in IRR row it decreased with depth, while being the opposite for NIR row. A possible explanation is that trees under irrigated treatment grow better and give more input of fresh OM (with low C/N ratio) to the soil. C/N ratio was higher in NIR row, which is in agreement with higher SOM content and lower biological activity in this treatment. The C/N value of 10 is considered optimal for a good incorporation rate of the organic matter into the soil profile. At lower slope positions, C/N ratio was around 7 and 8, indicating an intensive mineralization process. The velocity of mineralization processes in our soil samples may result from the presence of easily mineralizable decaying debris, which may cause a faster incorporation of this organic debris into the soil profile. This will be discussed in relation with microbial biomass and activity in treatments C/N ratios in the range 6-8:1 are usual from marine source, whereas higher ratios are likely to come from a terrestrial source (Dahlhem, 1988). Very low C/N ratio at upslope position could be explained by the hypothesis that here we are dealing mostly with SOM originating from the marl bedrock. Chemical analysis of upslope marl confirmed this statement, C/N of marl being as low as 4. Otherwise, such a low C/N is typical of the microorganisms (fungi and bacteria) containing more proteins than carbohydrates [START_REF] Miller | Understanding the Carbon-Nitrogen Ratio[END_REF].

CEC depends mainly on SOM and clay content of the soil (Rowel, 1994;Sposito, 2000). In IRR row, CEC decreased with depth due to decrease of SOM, while in NIR row CEC increased with depth due to clay increase. Higher CEC values at downslope position occurred due to higher SOM. This result was expected and agrees with Hanafi et al. (1992) andRowel (1994). Cation Exchange Capacity (CEC) was found to be slightly lower for the irrigated soils presumably due to the relatively lower OM content [START_REF] Murray | A review of Dr Bruce Cockroft's work for Australian irrigated Horticulture[END_REF]. Available phosphorus was slightly higher in the surface layer probably as the result of fertilization. More available phosphorus was found downslope. Phosphorus distribution showed a similar pattern as SOM content due to their association. Available phosphorus was roughly the same in the two treatments (IRR & NIR).

Slight increase of nitrates and ammonium with depth (especially in IRR row) occurred probably due to leaching with irrigation water. No difference in fertilisation occurred which could explain the difference between the treatments, while irrigation water might have participated to higher values of nitrates in IRR row. The highest values of mineral nitrogen were noticed at upslope position, what is not clear.

III.2 Spatial distribution of organic carbon and calcium carbonates

III.2.1 Distribution of Corg and CaCO 3 through soil profiles

In July 2006, two soil profiles were opened along the slope: at upslope and downslope positions. A dense sampling of the vertical profiles has been done from surface to bedrock. Analysis of organic carbon (Corg), total carbonates (total CaCO 3 ) and active lime are presented in Tab. 3.9.

From the Tab. III.5, some new information is noticed:

1. High level of organic carbon content was measured to the marl in both soil profiles, even if there is an important decrease from the surface to 25 cm. 2. The carbon content at downslope position between 56 and 66 cm depth was twice as higher than adjacent samples and confirmed the morphological observation of deep ploughing. 3. Organic carbon was still abundant in the marl bedrock. 4. Downslope profile showed that decarbonation occurred to the base of the deep ploughing (66 cm), which is related to dissolution of carbonates due to rain water in disturbed soil layer.

Tab. 3.9: Distribution of Corg, total CaCO 3 and active lime through soil profiles at upslope and downslope positions in Gačnik, July 2006. Marl sediment from upslope (60-65 cm) was additionally analysed on Corg (0.66 %), total carbonates (23.7 %), active lime (10.9 %) and C/N ratio ( 4).

III.2.2 Distribution of Corg along the slope in soil surface

In July 2006, carbon content was measured on the surface soil layer (0-5 cm) in order to appreciate its distribution along the slope, with samples taken every 6 m along the slope from irrigated and non-irrigated rows and from inter-row. Data are presented in Tab. 3.10 and Fig.

III.2.3 Discussion

Corg in the surface soil layer was increasing towards downslope, which initially be interpreted as a result of fine particle erosion accumulating organic matter downslope. A second fact is also important: Corg content was higher in the inter-row compared to the rows (NIR and IRR) and was also increasing towards downslope. The occurrence of a natural grass cover explained the higher amount of total carbon, but did not explain the increasing of Corg downslope. Indeed, in case of a covered soil surface, downslope erosion of fine particles is decreased. The second hypothesis is a higher input of organic matter from trees, coming from mechanical work and mulching in the inter-row (organic debris was removed from the tree line and spread in inter-row).

Further discussion is suggested when looking at the Corg distribution in the inter-row (Fig.

III.16).

A "zigzag" pattern can be seen when data are interpreted as: minimum values are corresponding to a normal increasing function and 3 maximum are observed at 296, 292 and 228 m height. It can be suggested that the shape is possibly related to the former planting system with terraces or resulting from soil engineering. High peaks of organic matter content can therefore be interpreted as remaining from previous surface layers of the terraces.

Focusing on the Corg results from September 2005 (in the surface layer only), a large difference was noticed at upslope position between IRR and NIR rows (0.79% and 1.28% respectively). When soils were sampled in July 2006, such a difference was not observed. We interpreted this as a result of different soil sampling: in September 2005, composite sample was analysed (mixed from ten subsamples); while in July 2006, punctual sampling with unique samples was made. For this reason, the results from September 2005 are more representative for comparison of the results according to slope, depth and irrigation. Sampling and analysing at both sampling dates was done by the same operator in the same laboratory

IV. Pore space characterisation

Certain physical soil parameters -bulk density and clod porosity corresponding to pore space characterisation, were measured in May 2004 and in May 2006.

In May 2004, soil samples for bulk density measurement were taken from downslope position: irrigated row (IRR), non-irrigated row (NIR), inter-row and under wheel. Three repetitions by depth were performed. In the surface layer (3-7 cm), only irrigated and nonirrigated rows were compared, while in the deeper layers (20-25 cm and 40-45 cm), a comparison among all four situations was done. Additional sample from 80-85 cm layer in inter-row was taken for characterisation of the undisturbed structural horizon.

Clod samples for determination of clods void ratio (e c ) were taken from IRR and NIR rows, inter-row and under wheel at different depths (20-30 cm, 40-50 cm and 80-90 cm).

In May 2006, soil samples for bulk density measurement were taken from the three slope positions in the irrigated and non irrigated rows at three depths: 0-5 cm, 10-15 cm and 20-25 cm with two repetitions by depth.

IV.1 Downslope position

IV.1.1 Bulk density

As shown in Tab. 3.11 and Fig. 3.21a & b, bulk density increased, while porosity decreased with depth, in IRR and NIR soils. Total void ratio decreased with depth in both water treatments, but significantly only in IRR row (average void ratio was 1.63 in the surface layer while 1.06 and 1.02 in deeper layers). Water saturation ratio increased with depth in both rows (IRR, NIR). In the Tab. 3.11 and Fig. 3.21a & b it can be noticed that voids from upper layer are less saturated with water than in deeper layers, especially in IRR soil. In inter-row, data referring to pore space characterisation and humidity were more or less the same according to depth.

In the surface layer (3-7 cm), significant difference in soil bulk density and total void ratio occurred between irrigated and non-irrigated soils: higher total void ratio was noticed in IRR (1.63) than in NIR (1.12) rows. In the surface soil layers, water saturation ratio was higher in NIR soil. Similarly, in inter-row and under wheels, water saturation ratio was higher comparing to rows (Fig. 3.21c &d). No significant differences among situations occurred in lower layers.

IV.1.2 Clods void ratio

In IRR and NIR rows, clods void ratio was more or less the same through the soil profile (Tab. 3.12). In inter-row, values of clods" void ratio slightly increased from the upper (20-30 cm) to deeper soil layers (40-50 cm & 80-85 cm) (Fig. 3.22). Due to large standard deviation of clods void ratio in the in mid-layer, the difference through the soil profile is not assured. In upper soil layers, no statistical significant differences in void ratio among situations occurred.

Tab. 3.12: Clods void ratio (e c ) and inter-clods void ratio in Gačnik, May 2004. The difference between total void ratio and clods void ratio presents inter-clods void ratio (e ic ). Inter-clods void ratio decreased with depth. In the sub-surface soil layer (20-30 cm), rows e ic was more or less the same and higher comparing inter-row e ic, while under wheels e ic was almost the half than in the rows.

IV.2 Variation along the slope

For a better understanding of soil physics along the slope, the study was continued in May 2006. Irrigated and non-irrigated soils were investigated at three slope positions: upslope, midslope and downslope. At each slope position, pore space characterisation from three soil depths was studied: 0-

NIR IRR

In May 2006, significant differences in total void ratio were obtained by depth, slope and treatment. According to depth, difference occurred between the first two (0-5 and 10-15 cm) and the third (20-25 cm) soil layers. Total void ratio was lower in the deepest studied layer (1.0 on average) comparing to the upper layers (on average 1.18 in the surface layer and 1.10 in the subsurface layer).

According to slope, soils from downslope position obtained the highest total void ratio (1.16 in average) and it differed from midslope position (1.03 in average). There was no significant difference in total void ratio between irrigated and non-irrigated rows, while higher values were observed in IRR row.

In the surface soil layer (0-5 cm), total void ratio at downslope position significantly differed from upper slope positions: at downslope position the total void ratio was the highest (1.44). Significant difference in total void ratio in the surface layer according to treatment was noticed at midslope position only, where total void ratio was higher in IRR soil.

In the mid-layer (10-15 cm), no statistical significant differences were noticed in total void ratio according to slope. In this layer, total void ratio in inter-row was the lowest and significantly differed from IRR soil at all slope positions. Significantly higher total void ratio in IRR soil occurred at down-slope only.

In the deepest soil layer (20-25 cm), no significant differences in total void ratio according to slope and treatment were noticed.

According to depth, gravimetric water content and water saturation ratio increased with depth: the surface layer was significant drier than lower soil layers. According to slope, water saturation ratio was the lowest upslope and the highest midslope. Comparing IRR and NIR rows, upslope NIR row was higher while IRR row was higher midslope. Downslope values were more or less the same.

IV.3 Discussion

Total void ratio decreased with depth, which could be explained with soil structure: till 5 cm. fine granular structure was observed, continued with subangular polyedric structure (5-15 cm), fine polyedric structure (till 30 cm) and from 60 cm coarse polyedric structure appeared. Comparing to granular and subangular polyedric structures, compact polyedric structure with low macroporosity is related to lower total void ratio and lower interclods void ratio. Evolution of soil structure could be related to SOM, clay content and climate. In the surface soil layer, where fine granular structure was observed, the content of SOM and percentage of clay were the highest and they decreased with soil depth. Our results were in agreement with [START_REF] Bachmann | Estimating soil stress distribution by using depthdependent soil bulk density data[END_REF], who also reported of void ratio decreasing through the soil profiles and with Challa (1987), who recorded the highest bulk density generally in the lower part of the profiles where more carbonate accumulation occurred. The degree of water saturation in pores significantly increased with depth, while gravimetric water content increased slowly. In deeper layers, pores inside clods were mostly filled with water and this could explain the appearance of hydromorphic features in lower layers.

Another pattern was observed in clods void ratio (at downslope position) according to depth, values increased with depth. In the subsurface layer (20-30 cm), fine polyedric structure was noticed and deeper, coarse polyedric structure appeared, which probably contributed to higher 91 clods voids ratio. Close to 60 cm deepness, dark brown soil volumes with high SOM content (3.25 % Corg) and massive structure were observed. Presumably, this could be a part of the previous surface layer buried by deep ploughing (increased variability of the pore space measurements), which is shown in Fig. 3.22. On the field, large variation in soil profile in inter-row was noticed with a mixture of soil volumes of different sizes. Large standard deviations of clods" void ratio till 50 cm deepness could improve this statement. A decrease of clod void ratio from the base undisturbed structural horizon to the surface horizons may be due to combination of natural compaction due to shrinkage and anthropogenic mechanical compaction.

In the surface layer (0-5 cm), soils from downslope indicated the highest total void ratio, which was expected due to higher SOM content. Structure in this layer was the same according to slope positions (fine granular). In the deeper layer (10-15 cm), total void ratio was higher at upslope position (in NIR row and inter-row). A possible explanation for this pattern could lie in the heterogeneity of soil in this study filed, or organisation of particles inside structure aggregates. Gravimetric water content and degree of saturation was the highest at mid-slope position and the lowest at upslope. Higher total void ratio in IRR row comparing to NIR row is difficult to interpret. Particle size distributions in both treatments were very similar, organic matter content in IRR soil was even lower and the structure (shape and size of aggregates) in both treatments was the same (fine granular structure). The reason for differences might result from arrangement of structure and manner of organisation inside the aggregates: looser fine granular structure in IRR soil comparing to more compact in NIR rows. Soils under wheels obtained significantly lower total void ratio than inter-row, IRR and NIR rows (at 20 cm) due to compaction with heavy machinery (tractor) and water saturation ratio was higher (Tab. 3.14). Several authors have reported some notable effects of irrigation on soil physical conditions. Our data showed a positive effect for the applied drip irrigation system on some soil physical properties. These findings are in harmony with the fact that the permanent irrigation system is associated with a cyclic of wetness followed by dryness. i.e., swelling and shrinkage cyclic formation, which enhances reorientation soil elements and impact on soil bulk density and total porosity that represent the most important factors of soil structure criteria [START_REF] Lawrence | Measurement of pore size in fine textured soils: A review of existent techniques[END_REF]. [START_REF] Zhao | -Land use change in Asia and the ecological consequences[END_REF] stated out irrigation did not result in any changes in soil particle distribution and in bulk density. Rajaram and Erbach (1998) a similar situation discussed; the effect of drying stress on bulk density was not significant on clay-loam soils. [START_REF] Rickard | Irrigation investigation in Otago, New Zealand, I. Description and physical properties of irrigated soils of the Ida Valley[END_REF] and [START_REF] Currie | Does Drip Irrigation Degrade Soil Structure in Vineyards? -18th World Congress of Soil Science[END_REF] found a decreasing porosity and a concomitant increase of bulk density in irrigated soils.

Tab. 3.14:

V. Organic matter characterisation and origin

To understand organic matter composition and origin better, a physical fractionation according to size in three fractions named A (> 200 μm), B (200-50 μm) and C (< 50 μm) was performed on soil samples from October 2004. On each fraction total carbonate content was determined and after decarbonatation, Corg, Norg and δ 13 C were measured (detailed measurements are presented in Annex 7).

V.1 Characterization of the grain size fractions

V.1.1 Grain size fractions abundance

Grain size fraction abundance is shown in Tab.3.15. Fraction A was the smallest and varies between 1.2 to 4.3 %, fraction B varies between 6 to 11 %, while C fraction was the largest and varied between 86 and 90 %. The three fractions were almost constant with depth, only fraction A was slightly higher in the surface layer than below. According to slope, fractions A and B in the surface layer slightly increased toward downslope. No differences in fraction distribution was noticed between IRR and NIR rows.

Tab. 3.15:

A, B and C fraction size (%) according to depth and slope position, in irrigated and in non-irrigated rows.

V.1.2 Total carbonates content

Total CaCO 3 content by fraction (g.100 g -1 ) and in proportion to the total amount by sample is shown in Tab. 3.16. Total carbonates dominated in fraction C at all slope positions and depths, while amounts of carbonates in fraction A were negligible. According to depth, no significant differences occurred in total carbonate content, while a slight increase with depth in fraction C was noticed. According to slope, upslope position contained significantly higher amounts of total carbonates than lower positions, where amounts were very similar. No differences occurred between irrigated and non-irrigated rows.

Tab. 3.16: CaCO 3 content (g.100 g -1 ) in the whole sample and in grain size fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows.

V.1.3 Organic carbon content

Total organic carbon content by fraction (g.100 g -1 ) and in proportion of the total amount by sample is shown in Tab. 3.17. Total organic carbon was lower upslope comparing to midslope and downslope (0.6 to 1.75 and 1.3 to 2.6 g.100 g -1 respectively). Organic carbon in fraction C represented 67 to 80 % of total Corg while 13 to 18 % for B fraction and 3 to 24 % for fraction A. OC content decreased in fractions A and B according to depth, while there was no particular trend for fraction C. According to slope, OC content in fraction A in the surface layer was lower upslope than at midslope and downslope. No significant difference was noticed comparing IRR and NIR rows where the mean OC contents were 0.51 and 0.46 g.100 g -1 , respectively. In fraction A only some differences occurred with a higher OC content in IRR than in NIR row (0.23 and 0.14 g.100 g -1 respectively).

Tab. 3.17: Organic carbon content (g.100 g -1 ) in the whole sample and in grain size fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows. Isotopic fractionation measurements ( 13 δC ‰) were performed to get information about the origin of soil organic matter. Our hypothesis was that in studied soils we had two types of organic matter: i) fresh OM mostly from apple trees and grass with low 13 δC (-28‰) and ii) sedimentary OM from marl with a higher 13 δC (-23‰) as discussed in chapter 3 III "Physicochemical soil characteristics". Our question was how much OM in each soil sample came from the tree and how much from the marl.

13 δC Isotopic composition by fraction is shown in Tab. 3.19 according to soil depth and slope position. Statistically significant differences in 13 δC according to fraction, depth, slope and treatment were found. According to fraction, mean value of 13 δC increased from fraction A to C. According to depth, mean value of 13 δC increased with depth. According to slope, upslope mean value of 13 δC was higher and differed from midslope and downslope (-25.32, -26.79 and -26.15 ‰ respectively). According to treatment, mean value of 13 δC was higher in IRR than in NIR rows (-25.99 and -26.18 ‰ respectively).

Tab

Distribution of fresh and sedimentary organic carbon stocks according to grain size fraction, depth, slope position and treatment

From OC content and 13 δC data of each fraction, the percentage of organic carbon which originated from fresh apple tree residue and from the weathering of the marl was calculated according the following mixing model for each fraction separately.

The 13 C of total soil organic matter and particle-size organic matter was intermediate between that of trees and marl sedimentary bedrock. Organic carbon derived from trees (C t ) and from the bedrock (C b ) in any sample from a soil layer or soil organic matter fraction was expressed as C (mg.g -1 ), or as a percentage of total C (PC t and PC b ) of the respective layer or soil organic matter fraction, as follows :

C t = C c . ( c -b ) / ( t -b ), C b = C c -C t PC t = 100 . C c . ( c -b ) / ( t -b ), PC b = 100 -PC t
where C C is the total C content of the sample from the cultivated soil (layer or fraction), c is the 13 C value of the sample analyzed, b is the 13 C value of sample from the corresponding bedrock from a deeper layer (60 cm depth) here taken as -23.32 ‰, and t is the 13 C value of the apple tree residues here taken as -28.11 ‰, used as reference.

Sedimentary and fresh organic stocks in 0 -30 cm layer were calculated, taking into account the proportion of each fraction in a layer, the thickness of the layer and a mean bulk density for IRR and NIR rows of 1.23 and 1.28 g.cm -3 , respectively, calculated from Table III.13a&b.

Results were presented in two ways:

-first, by tons per hectare and per centimeter (T.ha -1 .cm -1 ) for each layer (0-5, 5-15 and 15-30 cm), grain size fraction, position and treatment in Tab. 3.20 and in Fig. 3.24a &b, where the influence of depth, slope and treatment on the distribution of the two types of OC will be discussed; -and second, by tons per hectare on the whole 0-30 cm layer for each grain size fraction, position ant treatment in Fig. 3.25 and Tab. 3.21.

According to treatment, no significant differences in stock of total, fresh and sedimentary OC in T.ha -1 .cm -1 were found (Tab.3.20). Total and fresh OC stocks decreased with depth, while sedimentary OC stock was more constant through the profile. Along the slope, total, fresh and sedimentary OC stocks increased towards downslope. Both types of OC stocks were the highest in C fraction.

Tab. 3.20: Stocks of sedimentary and fresh organic carbon (OC) in T.ha -1 .cm -1 in fractions A, B & C according to depth and slope position, in irrigated (IRR) and non-irrigated (NIR) rows

Fresh OC Fresh OC Fresh OC A B C Sed OC A B C Sed OC A B C
Sed OC Fresh 0,08 0,11 0,20 0,39 0,83 0,57 1,43 2,83 0,05 0,40 0,84 1,29 Sedimentary 0,06 0,08 0,62 0,76 0,00 0,01 0,33 0,34 0,64 0,14 0,85 1,63 Fresh 0,07 0,05 0,08 0,20 0,03 0,21 0,55 0,79 0,11 0,21 0,63 0,95 Sedimentary 0,05 0,09 0,59 0,73 0,01 0,07 0,75 0,83 0,06 0,13 0,79 0,98 Fresh 0,09 0,03 0,00 0,12 0,10 0,27 0,86 1,23 0,18 0,23 0,72 1,13 Sedimentary 0,06 0,08 0,56 0,70 0,03 0,10 0,81 0,94 0,14 0,11 0,83 1,08 Fresh 0,14 0,11 0,17 0,42 0,23 0,30 0,76 1,29 0,19 0,35 0,76 1,30 Sedimentary 0,07 0,09 0,64 0,80 0,02 0,06 0,80 0,88 0,10 0,14 0,89 1,13 Fresh 0,14 0,15 0,35 0,64 0,08 0,24 0,82 1,14 0,11 0,19 0,83 1,13 Sedimentary 0,06 0,10 0,63 0,79 0,02 0,07 0,80 0,89 0,03 0,09 0,90 1,02 Fresh 0,07 0,02 0,01 0,10 0,09 0,18 0,59 0,86 0,15 0,23 0,80 1,18

Sedimentary 0,03 0,10 0,56 0,69 0,02 0,08 0,78 0,88 0,03 0,07 0,82 0,92 Considering that fraction C prevailed in this soil, distribution of sedimentary and fresh organic carbon stocks (T.ha -1 .cm -1 ) in this fraction were presented according to slope, treatment and depth in Fig. 3.24a & b. Sedimentary OC stocks showed no significant variations according to depth and treatment excepted for the surface layer of irrigated row at midslope position, while it increased steadily from upslope to downslope (0.60, 0.71 and 0.85 T.ha -1 .cm -1 , respectively). Fresh OC stocks showed wider variations according to depth and treatment with ranges of 0.4, 0.8 and 0.2 T.ha -1 .cm -1 from upslope to downslope and no clear trends according to depth and treatment. According to slope, mean fresh OC stock was very low upslope while similar to sedimentary OC stock at midslope and downslope positions (0.13, 0.63 and 0.76 T.ha -1 .cm -1 respectively). Integration of the stocks of OC (T.ha -1 ) on 0 -30 cm showed that the ratio between sedimentary and fresh organic matter differed according to grain size fractions and slope position (Tab. 3.20 and Fig. 3.25). Focusing on the size fraction, sedimentary organic carbon prevailed in fraction C (especially at upslope). In fraction A, fresh organic carbon predominated (78 % of total OC). According to slope position, sedimentary OC strongly predominated at upslope position, where it represented 73 % of total OC. No significant differences in sedimentary and fresh OC stocks occurred between irrigated and non-irrigated row. Measurements of sedimentary and fresh OC stock (0-30 cm) according to size fraction, slope position, and treatment are presented in Annex 8.

Tab. 3.21:

Sedimentary versus fresh Organic carbon (OC) stock ratios in 0-30 cm layer (T.ha -1 ) according to size fraction, depth, slope position and treatment.

(from Fig. 3.25 it can be seen that the situation according to sedimentary OM in fraction A in IRR row at downslope position differed completely from all others values from fractions A and B. It could be possibly related to the presence of a sand size particle of marl in the analysed sample)

V.2 Discussion

The fractionation of soil based on physically defined grain size fractions is used increasingly to interpret the dynamics of SOM. This method can provide useful information on SOM dynamics under natural conditions or short-term management practices [START_REF] Piccolo | Organic carbon fractions in a yerba mate plantation on a subtropical kandihumult of Argentina[END_REF][START_REF] Sevink | Land-use related organic matter dynamics in North Cameroon soils assessed by 13C analysis of soil organic matter fractions[END_REF][START_REF] Olk | Overview of the symposium proceedings, -Meaningful pools in determining soil carbon and nitrogen dynamics[END_REF][START_REF] Shrestha | Soil Aggregate and particle-associated organic carbon under different land uses in Nepal[END_REF]. For this reason, physical fractionation have been proposed to analyze the processes of organic matter stabilization in soils [START_REF] Christensen | Physical fractionation of soil and organic matter in primary particle size and density separates[END_REF][START_REF] Golchin | A model linking organic matter decomposition, chemistry, and aggregate dynamics[END_REF].

In our study soil texture was silty clayey, therefore fraction C (fine silt + clay) was the main fraction of the total soil mass (90 %). Organic carbon content was the highest in fraction A, while in whole bulk soil fraction C represented the main stock of SOM. This is in accordance with other authors [START_REF] Ducaroir | Evidence of trace metal association with soil organic matter using particle size fractionation after physical dispersion treatment[END_REF]Florez-Velez et al., 1996;[START_REF] Rumpel | Location and chemical composition of stabilized organic carbon in topsoil and subsoil horizons of two acid forest soils[END_REF], who found that soil organic carbon is mainly located in the finest size fractions <20 µm and generally increase with decreasing particle size [START_REF] Amelung | Carbon, nitrogen, and sulfur pools in particle-size fractions and influenced by climate[END_REF][START_REF] Zinn | Edaphic controls on soil organic carbon retention in the Brazilian Cerrado: Texture and Mineralogy[END_REF].

Fraction C was also rich in carbonates. It is generally accepted that calcium is a critical element for stabilization of SOM and aggregates [START_REF] Six | A history of research on the link between (micro)aggregates, soil biota, and soil organic matter dynamics[END_REF], inducing higher structural stability in soil samples with high carbonate content.

Fraction A was the smallest, but the most variable fraction, responding to slope (most at downslope) and depth (most in the surface layer). In fraction A, percentage of carbonates were almost negligible. The only significant difference in OC between IRR and NIR rows was found in fraction A. For this reason, the coarse fraction is an important indicator of the SOM quality, what was in agreement with [START_REF] Christensen | Physical fractionation of soil and structural and functional complexity in organic matter turnover[END_REF].

The C/N ratio is related to the degradation of fresh plant residues, and is important in Corg sequestration potential [START_REF] Potter | Distribution and amount of soil organic C in long-term management systems in Texas[END_REF][START_REF] Onweremadu | Carbon and nitrogen distribution in water-stable aggregates under two tillage techniques in Fluvisols of Owerri area, southeastern Nigeria[END_REF]. High C and N concentrations were found in the unprotected free OM fraction. Unprotected organic matter fractions are often relatively labile with high concentrations of carbohydrates and nitrogen compounds [START_REF] Skjemstad | The chemistry and nature of protected carbon in soil[END_REF][START_REF] Golchin | Study of free and occluded particulate organic matter in soils by solid state 13C CP/MAS NMR spectroscopy[END_REF][START_REF] Golchin | The effects of cultivation on the composition of organic matter and structural stability of soils[END_REF]. With increasing degree of decomposition, organic matter may be transferred to more stabilized soil fractions.

In our study, C/N ratio was the highest in fraction A and it decreased in finner fractions. Our results are supported by some authors [START_REF] Christensen | Physical fractionation of soil and organic matter in primary particle size and density separates[END_REF][START_REF] Christensen | Physical fractionation of soil and structural and functional complexity in organic matter turnover[END_REF][START_REF] Buyanovsky | Carbon turnover in soil physical fractions[END_REF][START_REF] Plante | -Impact of soil texture on the distribution of soil organic matter in physical and chemical fractions[END_REF], who found that SOM in coarse fractions is usually less decomposed and has a high C/N ratio. The nature and the turnover of the organic carbon in the finest fraction are different from the other particle size fractions probably due to less favourable conditions for mineralization [START_REF] Rumpel | Location and chemical composition of stabilized organic carbon in topsoil and subsoil horizons of two acid forest soils[END_REF][START_REF] Balesdent | The significance of organic separates to carbon dynamics and its modelling in some cultivated soils[END_REF]. Moreover, C/N ratio in fraction C is smaller than fractions A and B, and its variations are narrower because organic carbon is relatively more stable due to sorption mechanisms [START_REF] Christensen | Physical fractionation of soil and organic matter in primary particle size and density separates[END_REF][START_REF] Christensen | Physical fractionation of soil and structural and functional complexity in organic matter turnover[END_REF][START_REF] Buyanovsky | Carbon turnover in soil physical fractions[END_REF][START_REF] Plante | -Impact of soil texture on the distribution of soil organic matter in physical and chemical fractions[END_REF].

In our study, C/N ratio in fraction A increased with depth whatever the SOM content. Higher C/N ratio occured in IRR than in NIR row, which indicates higher OM input from more developed irrigated trees. Very low C/N ratios were found at upslope, especially in the deepest layer, where sedimentary OM predominated.

Molecular 13 C signatures of organic matter (OM) are nowadays used for many purposes (Lichtfouse, 2000). Since 1985, the use of 13 C natural abundance technique, coupled with particle size fractionation allowed great progress in SOM turnover studies and to characterize SOM changes through time discriminated by SOM origin [START_REF] Cerri | Application du traçage isotopique naturel en 13 C à l"étude de la dynamique de la matière organique dans les sols[END_REF][START_REF] Sevink | Land-use related organic matter dynamics in North Cameroon soils assessed by 13C analysis of soil organic matter fractions[END_REF]. The 13 C composition of SOM changes during its decay because 12 C is preferentially used by decomposers, resulting in enrichment in 13 C of the remaining SOM (Andreux et al., 101 1990;[START_REF] Martin | Estimate of organic matter turnover rate in a savanna soil by 13C natural abundance measurements[END_REF][START_REF] Desjardins | Organic carbon and 13C contents in soils and soil size-fractions, and their changes due to deforestation and pasture installation in eastern Amazonia[END_REF][START_REF] Balesdent | Measurement of soil organic matter turnover using 13C natural abundance[END_REF][START_REF] Boutton | Stable carbon isotope ratios of soil organic matter and their use as indicators of vegetation and climate change[END_REF][START_REF] Koutika | Organic matter dynamics and aggregation in soils under rain forest and pastures of increasing age in the eastern Amazon Basin[END_REF]. Because of these processes, soil organic constituents can be 13 Cenriched by 1.5-4.3 ‰ relative to homogenous plant constituents [START_REF] Lichtfouse | Unexpected 13C-enrichment of organic components from wheat crop soils: evidence for the in situ origin of soil organic matter[END_REF].

In our study, we found a high δ 13 C signature in fraction C corresponding to very low C/N ratio, which usually occurs in fresh OM like algaes and it is easily degraded by microbes. We attributed this signature to the marl bedrock which contains sedimentary OM with very low C/N ratio. As shown by Fig. 3.26a, a good correlation between Corg and C/N was found: the accumulated Corg (mainly originating from plant OM) has higher C/N ratio, while its 13 δC decreases sharply, and is more negative than 13 δC from marl (Fig. 3.26b). This is also illustrated by Fig. 3.26c, where OM with low C/N ratio (from marl) has higher 13 δC than OM originating from plants, characterized by a higher C/N ratio.

Using a mixing model with δ 13 C of marl and δ 13 C of fresh OC, we were able to quantify the sedimentary (fossil stock) and fresh (present) OC in the soil. In accordance with a statement that older OC has higher 13 δC, more sedimentary OC (as a concentration) was found in fraction C and more fresh OC (as a concentration) in fraction A and B, as expected. By considering soil OC stock according to proportions of each grain size fraction in this soil, higher stock of sedimentary and fresh OC occurred in fraction C. Fresh OC was mostly present in the middle of the slope and in the surface layer as a stock, where total OC was also high. The opposite situation appeared with sedimentary OC: on concentration level, it was mostly present at upslope position and in the deepest layer (similar pattern as total carbonates). When we are focusing on the stock of sedimentary OC (considering proportions of each grain fraction in this soil), no significant differences occurred in this type of OC according to depth, while small increasing at downslope was noticed.

The effect of land use on the composition and distribution of OM in size fractions is well known [START_REF] Puget | Nature of carbohydrates associated with waterstable aggregates of two cultivated soils[END_REF]. The change in land use alters the rate at which the organic matter is oxidized, therefore affecting its accumulation and mineralization [START_REF] Solomon | Soil organic matter dynamics in the subhumid agroecosystems of the Ethiopian highlands: evidence from natural C-13 abundance and particle-size fractionation[END_REF].

According to irrigation, no significant differences were observed in distributions of size fractions, OC content and total carbonates according to depth and slope. The impact of irrigation was noticed only inside fraction A, where higher Corg content and higher C/N ratios were noticed in IRR soil. This could be explained by a higher input of fresh organic matter from more developed irrigated trees. Previous studies have also indicated that changes in land use (or management practices) have a marked impact on fraction A, which could serve as an early indicator to identify the impact of landuse change on soil Corg storage matter entrapped [START_REF] Christensen | Physical fractionation of soil and structural and functional complexity in organic matter turnover[END_REF][START_REF] Solomon | Soil organic matter dynamics in the subhumid agroecosystems of the Ethiopian highlands: evidence from natural C-13 abundance and particle-size fractionation[END_REF][START_REF] Leifeld | Soil organic matter fractions as early indicators for carbon stock changes under different land-use?[END_REF]. In contrast, mineral-associated organic matter and organic at sites inaccessible to microbial attack or physically protected within soil aggregates belong to more stable organic matter pools with a turnover time of decades to centuries [START_REF] Christensen | Physical fractionation of soil and organic matter in primary particle size and density separates[END_REF][START_REF] Piccolo | Humus and soil conservation[END_REF][START_REF] Golchin | A model linking organic matter decomposition, chemistry, and aggregate dynamics[END_REF].

VI. Microbiological soil characteristics

Several microbiological soil characteristics were measured at different seasons and locations along the slope during two years to follow spatial and temporal variations of these parameters according to season, slope position and treatment. The following parameters were measured: microbial biomass (BM), labile organic matter pool (LOM) and microbial respiration and N mineralization after a 28 days incubation (Cmin, Nmin).

As a preliminary study, analyses were done in May 2004 on samples from two water treatments (IRR, NIR) and two depths (0-10 and 20-30 cm) at downslope position. In September 2004 we continued with sampling from both treatments again, while this time samples were taken at six positions from midslope to downslope and for 0-15 cm and 15-30 cm depths. Next year ( 2005) in May we also included the possible effect of sun exposure (sunny and shady sides of each studied row) and soil samples were taken from the upslope to downslope at eight different positions (to the same depths as previously). The last sampling for basic microbial analyses was done in September 2005: soil samples were taken from three positions on the slope (upslope, midslope and downslope) and sun exposure was still included.

VI.1 Soil physico-chemical characteristics and wetness at the sampling periods

For interpreting microbial results, soil wetness at the sampling periods and some physicochemical soil analyses were done.

VI.1.1 Organic carbon and nitrogen, C/N and exch. Cu

For a preliminary study, initial soil analyses were done only at downslope position (pH, Corg, Norg and Cu) (Tab. 3.22). Soil pH was measured in all sampling periods, but the mean values were always higher than 7.5 and no differences were noticed. Therefore, pH variations were not relevant for explaining microbiological properties and activity. Carbon, nitrogen and copper content were more or less the same to 30 cm in depth in both treatments, while slight higher values were noticed in the surface soil layer of IRR row. Gravimetric water content (W) is important especially for interpreting soil microbial biomass and its activity as a consequence of weather conditions and added water by irrigation. For this reason it was measured at every sampling date, in parallel with microbial soil parameters.

104

In May 2004, water gradient showed a slightly higher percentage in NIR soil and in the deeper layer, but it has to be emphasized that no irrigation had been applied until this date (Fig. 3.27).

Fig. 3.27:

Mean value of gravimetric water content (%) at downslope position according to depth and traitment, May 2004.

In September 2004, water gradient was measured in the lower half of slope (from midslope to downslope) with four intermediate positions. NIR row still had a significantly higher gravimetric water content than IRR row in both soil layers. In the lower half of slope, more or less the same gravimetric water content was measured in upper layer, while in the deeper layer a slight increase towards downslope was noticed. Soil moisture was higher in upper soil layer (0-15 cm) (Fig. 3.28). In September 2005, W significantly differed between water treatments: W was higher in NIR than in IRR row and showed an increasing trend towards downslope in both soil layers. There was no obvious difference according to depth but sun exposure significantly affected W: the shady side being wetter than the sunny side (Fig. 3.30). As basic microbial properties a few parameters were measured: microbial biomass (BM), labile organic matter pool (LOM) and microbial respiration after a 28 days incubation (Cmin, Nmin).

As a preliminary study, analyses were done in May 2004 on samples from two water treatments (IRR, NIR) and two depths (0-10 and 20-30 cm) at downslope position. In September 2004 we continued with sampling from both treatments again, while this time samples were taken at six positions from midslope to downslope and for 0-15 cm and 15-30 cm depths. Next year ( 2005) in May we also included the possible effect of sun exposure (the sunny and the shady sides of each studied row) and soil samples were taken from the upslope to downslope at eight different positions (to the same depths as previously). The last sampling for basic microbial analyses was done in September 2005: soil samples were taken from three positions on the slope (upslope, midslope and downslope) and sun exposure was still included. Complete measurements of microbial parameters are presented in Annex 9 (in 2004) and in Annex 10 (in 2005).

VI.2 Spatio-temporal variation of the biological parameters

VI.2.1 May 2004

Microbial biomass (BM)

In May 2004, IRR row showed significantly higher biomass values than NIR row (Duncan test at 95 % confidence level) in the upper soil layer, while in the deeper soil layer the values were more or less the same (Fig. 3.31). Microbial biomass level was consistent with total organic matter content. In IRR treatment, BM represented 3.04% of total Corg, and only 2.75% in NIR treatment (in upper soil layer). This figure, as absolute values, confirmed a better organic status in the IRR row.

According to depth, the the upper soil layer (0-10 cm) showed a much higher microbial biomass than the deeper layer (20-30 cm), which was expected from the higher percentage of organic matter in the upper layer.

Labile organic matter pool (LOM)

Labile organic matter pool was analysed only in the upper soil layer (0-10 or 0-15 cm), except in spring 2004 where the deeper layer was also included (20-30 cm) (Fig. 3.32). In May 2004, similar pattern of LOM values occurred as with biomass. According to irrigation, statistically significant difference in labile organic matter pool (LOM) was noticed only in the upper soil layer, where more LOM was detected in IRR row than NIR one (8.33% and 7.30% of total Corg respectively). Significantly more LOM was present in the upper soil layer than in the deeper soil layer, in accordance with total soil organic matter.

Microbial respiration (C mineralization)

In May 2004, C mineralization (respiration) was significantly more intensive in IRR treatment in both soil layers, in agreement with the results of microbial biomass. According to depth, the upper soil layer (0-10 cm) produced more mineral C by respiration than the lower layer, what is in accordance with the results of microbial biomass and labile organic carbon pool (Fig. 3.33). Microbial respiration and microbial biomass were combined to calculate two derived parameters: specific respiration and time of turnover (Tab. 3.23). Specific respiration (qCO 2 ) is the amount of Cmin produced per day and per unit of microbial biomass. Time of turnover is the inverse of specific respiration: 1*(spec. respiration) -1 .

In IRR row, more intensive respiration of soil microbes was recorded. In the deeper soil layer, more mineral CO 2 was produced per unit of microbial biomass (Tab. 3.23). Indeed, the soil samples were incubated in optimal conditions which are not representative of in situ conditions, where various limiting factors (aeration, substrate availability etc.) prevailed.

Distribution of soil organic matter components in total Corg

Total soil organic carbon can be represented by three main components: microbial biomass (C-MB), labile organic matter pool (C-LOM) and stable organic matter (C-StOM). Differences may occur in proportions of these components within total Corg.

Stable OM represented the most part of total Corg, while LOM was at least twice the part of microbial biomass. The percentage of active organic carbon (microbial biomass and LOM) according to total Corg was higher in IRR row compared to NIR, especially in the upper soil layer. In the lower soil layer (20-30 cm), percentage of stable OM in total Corg increased, while microbial biomass and LOM decreased (Fig. 3.34).

VI.2.2 September 2004

Microbial biomass

In autumn 2004 we continued with more detailed sampling and the analyses were performed from midslope to downslope with some intermediate positions.

In September 2004, statistical significant difference in microbial biomass according to irrigation was noticed again, with more microbial biomass in IRR soils. According to slope, a clear trend of biomass increase towards downslope in the upper layer was noticed, the highest values being detected at downslope and the lowest in midslope position. Biomass significantly decreased with soil depth (Fig. 3.35). Labile organic matter pool LOM was analysed in the surface layer only (0-15 cm). Irrigation effect was less significant, while LOM values changed along the slope: in the first part of slope more LOM was present in IRR row, while in the upper position the situation changed (Fig. 3.36). Along the slope, some significant differences occurred: the highest LOM values were recorded downslope and the lowest at position 5 (near midslope). This is consistent with variations of some physicchemical characteristics of the soil samples (clay content, CEC etc.) according to the position of the slope and may result from soil movement (levelling of terraces). In addition, at down slope position, fine soil particles rich in OM (and LOM) can accumulate as the result of soil erosion.

Fig. 3.36: Distribution of labile organic matter pool (LOM) from midslope to downslope, Gačnik, September 2004.

Microbial respiration (C mineralization)

Statistical significant differences in microbial respiration were noticed according to the treatment, slope and depth. IRR row released more CO 2 than NIR row, especially in the lower slope positions. The highest mineralization rate occurred downslope and it decreased towards midslope (Fig. 3.37). Cmin decreased with depth, as microbial biomass. More intensive respiration of soil microbes (and shorter time of Corg turnover) was noticed in IRR row, especially at midslope, which could be a consequence of added water during the summer (Tab. 3.24). Specific respiration was slightly higher in the deeper soil layer, especially downslope -the field conditions were probably not optimal like during the incubation process. Higher moisture in the deeper soil layer could be the reason for enhanced C mineralization.

Tab. 3.24: Spec. respiration (day -1 ) and turnover time (day), Gačnik, September 2004.

Mid-slope

N mineralization

Values of ammonium nitrogen were negligible in this soil (NH 4 + concentration was low in irrigation water as well), while irrigation significantly increased nitrates in soil. Along the slope, the highest values were recorded at midslope position and they significantly differed from downslope position. Intermediate positions showed zig zag pattern in nitrates values, as observed for Corg distribution along the slope (Fig. 3.38). No differences according to depth were noticed.

Distribution of soil organic matter components in total Corg

A slightly higher percentage of active OM components (BM and LOM) was noticed in IRR soil, especially downslope, confirming the results from the previous sampling in May 2004 (Fig. 3.39).

Fig. 3.39: Distribution of soil organic matter (SOM) components in total Corg in upper soil layer (0-15 cm), Gačnik, September 2004.

VI. 2.3 May 2005

In the year 2005, the effect of sun exposure was included in the study. For this purpose, each row (water treatment) was separated into the shady and sunny side. The top of the slope was also included in this study. As no irrigation was done this year, analyses of Cmin from microbial respiration were not performed.

Microbial biomass

In May 2005, no statistically significant differences in microbial biomass were noticed between IRR and NIR rows (Fig. 3.40a & III.48b). According to slope microbial biomass increased from upslope to downslope. Biomass also decreased with depth. Significant difference occurred between the shady and the sunny side of the row, with higher microbial biomass at the sunny side.

Labile organic matter pool

No important differences in LOM were noticed between IRR and NIR rows: upslope, more LOM in NIR row was detected, while downslope the situation was the opposite (Fig. 3.41).

Along the slope, LOM values increased from upslope to downslope. Sun exposure did not significantly affect LOM, only a slight tendency for higher values in the shady side was noticed.

VI.2.4 September 2005

In September 2005, comparison of IRR versus NIR rows at three main positions of the slope was made: downslope, midslope and upslope.

Microbial biomass

Comparing soil microbial biomass under the two different water treatments, significantly higher values were detected in NIR row (Fig. 3.42a & b). Along the slope, significant differences occurred as well, biomass increasing from upslope to downslope, especially in irrigated row. Soil depth did not affect biomass, but sun exposure showed significantly higher values in the shady side. Higher values of microbial biomass mostly followed higher soil moisture.

Labile organic matter pool (LOM)

Between IRR and NIR rows statistical significant difference occurred in LOM content: NIR row contained more LOM than IRR row. LOM significantly increased towards downslope. Sun exposure affected LOM in the sense of higher values in the shady side (Fig. 3.43).

VI.3 Discussion

The activity of aerobic microbes is greatly dependent on soil water content which governs transport of oxygen and substrates [START_REF] Papendick | Theory and measurement of water potential[END_REF][START_REF] Skopp | Steady-state aerobic microbial activity as a function of soil water content[END_REF][START_REF] Young | Tillage, habitat space and function of soil microbes[END_REF]. Water dynamics and stress exert a major influence on microbial physiology and function [START_REF] Harris | Effect of Water Potential on Microbial Growth and Activity in Soils in Water Potential Relations in Soil Microbiology[END_REF][START_REF] Yancey | Living with water-stress evolution of osmolyte systems[END_REF][START_REF] Kempf | Uptake and synthesis of compatible solutes as microbial stress responses to high-osmolality environments[END_REF], however, there is still considerable debate about how water stress affects soil microbial communities, their biomass, and their overall activity. Eventually, water stress can be alleviated by irrigation in agro-ecosystems. For these reasons, gravimetric water content was measured in parallel with microbial parameters.

In spring (May 2004 and2005), higher soil moisture was measured in deeper soil layer, the situation being the opposite in autumn (September 2004 and2005). Distribution of soil water through the soil profile depends on the weather (rainfall, evaporation), the surface cover and structural stability. In spring, bare soils probably lost some water from the surface layer due to evaporation, while in autumn, plant cover could contribute to higher soil moisture in the surface soil layer. In spring, higher WSA was measured compared to autumn, and this could help water infiltration through the soil profile.

Along the slope, a trend of increasing soil moisture towards downslope was noticed, probably due to higher SOM content and downhill water run-off. Gravimetric water content was high at downslope and midslope positions, while soil from upslope position was the driest. Soils from the shady side of the rows always showed higher gravimetric water content, which was presumably linked with the presence of blue-green algae at this location. Indeed, both C availability and water regime are implicated as major determinants of soil microbial community structure and activity in both laboratory and field experiments [START_REF] Zhang | Potential physiological activities of fungi and bacteria in relation to plant litter decomposition along a gap size gradient in a natural subtropical forest[END_REF][START_REF] Wilkinson | PLFA profiles of microbial communities in decomposing conifer litters subject to moisture stress[END_REF][START_REF] Drenovsky | Soil water content and organic carbon availability are major determinants of soil microbial community composition[END_REF].

The interaction of soil microbes with their physical environment affects their abilities to respire, grow and divide. One of these environmental factors is the the soil wetness. In our study, there was a strong negative correlation between soil moisture and microbial biomass in spring 2004 (correl. coef. = -0.97 at 99% confidence level; R 2 explained 95% of the variability of MB with linear model: MB=2878-88.4*W). Too much moisture also had a negative effect on soil respiration (Cmin) (linear correl. coef.= -0.74; R 2 =55%). During this period, mean water saturation ratio increased very quickly with depth (Tab. 3.11): in IRR row from 0.76 (in 20-25 cm layer) to 0.84 (in 40-45 cm layer) and in NIR from 0.82 to 0.95. It also has to be taken into account that those figures are measured in the cylinders with 100 cm3 volume, while microbes are mostly present inside the clods, where there is presumably even higher water saturation according to silt clayey texture. [START_REF] Hillel | Fundamentals of Soil Physics[END_REF] found that microbial respiration was linearly related to soil-water content and log-linearly related to water potential. Obviously this linear relationship between soil respiration and water content applies only on the first part of the curve until the optimum water content (enabling also good aeration). Beyond this optimum, the relationship becomes negative, due to limited oxygen availability.

Changes in soil moisture, temperature and C input can have a large effect on the soil microbial biomass and its activity, which, in turn, affect nutrient availability due to soil organic matter turnover [START_REF] Ross | Soil microbial biomass estimated by the fumigation-incubation procedure: seasonal fluctuations and influence of soil moisture content[END_REF]. Microbial biomass, labile organic matter pool and respiration rate mostly decreased with depth, as did soil organic status. Gravimetric water content showed variations with both sampling depth and season: in spring water content mostly increased with depth and decreased in autumn. Since organic matter and soil microbial activity are typically concentrated in the top few centimetres of soil [START_REF] Murphy | Stratification of microbial biomass C and N and gross N mineralization with soil depth in two contrasting Western Australian agricultural soils[END_REF], there is generally a positive linear relationship between soil organic C content and microbial biomass C [START_REF] Sparling | Soil microbial biomass, activity and nutrient cycling as indicators of soil health[END_REF][START_REF] Rietz | Effects of irrigation-induced salinity and sodicity on soil microbial activity[END_REF]. However this was not the case in our study, where IRR soil contained a lower SOM, but higher MB. Indeed mineralization processes, as shown by lower C/N ratio of SOM and higher respiration (Cmin) are more intensive in IRR soil, with lower remaining SOM in this treatment. Microbial biomass, labile organic matter pool and respiration always increased from upslope toward downslope, which was positively related to SOM content. Distribution of microbial biomass, respiration rate and labile organic matter pool along the slope was similar to distribution of total Corg (zigzag pattern), and was presumably the result of soil movement when changing the previous system (with terraces) to the new one (rows on the slope).

Sun exposure had no general effect on soil microbes, even if gravimetric water content was always higher at shady side: in May 2005, higher microbial biomass was measured at the sunny side, and in September 2005 at the shady side.

To analyse the irrigation effect on soil microbial biomass, we focused on the results from 2004 (especially on September, as short-term effect), when irrigation was really performed. This period could also reflect previous irrigation seasons as well (long-term effect). In the year 2005, no irrigation was done.

At the beginning and the end of the 2004 growing season, irrigation positively affected microbial activity in sense of higher biomass, LOM and higher respiration rate in the upper soil layer. Comparing proportions of different components of SOM, differences between water treatments were observed, especially in the upper soil layer where IRR soils had more active SOM (microbial biomass and LOM). These results were not related to gravimetric water content. We can conclude that in our study organic matter status is a more important factor than water status.

In 2005, the situation according to water treatment was the opposite, but it should be emphasized again that no irrigation was done this year. In the beginning of the season 2005, no significant differences in microbial biomass and in LOM were observed between IRR and NIR rows. At the end of this season, microbial biomass and organic matter pool were higher in NIR row, but this was not a direct (short term) consequence of irrigation. Results of biomass and LOM in autumn 2005 followed the pattern of soil moisture which was itself related to SOM content. If irrigation modifies root distribution and consequently water regime, the effect of previous irrigation by modifying root system still may occurred on water regime even without irrigation. Between years, the variations of the parameters related to soil microflora were influenced by the seasonal climatic trend.

Several authors reported positive effects of irrigation on soil microbial biomass. Irrigation can increase C input to soils via increased crops and root production and thus increase of active microbial biomass is expected [START_REF] Entry | Influence of irrigated agriculture on soil microbial diversity[END_REF][START_REF] Melester | USDA-ARS, 94 th ESA annual meeting[END_REF]Ramirez-Fuentez, 2002). [START_REF] Martiniello | Biochemical parameters in a Mediterranean soil as affected by wheatforage rotation and irrigation[END_REF] showed that irrigation favoured microbial activity in Mediterranean climate. Management practices of irrigated land, including yearly fertilizer application, results in the addition of young OM to irrigated soil which contributes to the production of mineral N from labile organic matter. The labile OM acts as a substrate for microorganisms and is readily decomposed, turning over large amounts of N [START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF]. Contents of total and labile OM and microbial biomass were significantly affected by different irrigation regimes, and decreased with soil depth, while drip irrigation increased microbial biomass [START_REF] Han | Effect of Different Methods on Dissolved Organic Carbon and Microbial Biomass Carbon in the Greenhouse Soil[END_REF][START_REF] Melester | USDA-ARS, 94 th ESA annual meeting[END_REF][START_REF] Samuelson | Soil and microbial respiration in a loblolly pine plantation in response to seven years of irrigation and fertilization[END_REF]. Other authors (such as [START_REF] Swarts | Soil community structure and litter decomposition under irrigated Eucalyptus globulus in south western Australia[END_REF] found that neither microbial biomass nor respiration was significantly affected by irrigation. Intermittent irrigation did not affect soil respiration evidently, despite the significant effect of water content on soil respiration [START_REF] Kucera | Soil respiration studies in tall-grass prairie in Missouri[END_REF]Kirkham, 1971, Tesarova and[START_REF] Tesarova | -Total CO2 output from alluvial soils with two types of grassland communities[END_REF]. Maybe the variation of soil respiration lagged behind the change of water content.

Because mineralization is performed by the microbial biomass, it is often assumed that this process is at least partly regulated by its size, specific activity or composition [START_REF] Marschner | Controls of bioavailability and biodegradability of dissolved organic matter in soils[END_REF][START_REF] Fontaine | Size and functional diversity of microbe populations control plant persistence and long-term soil carbon accumulation[END_REF]. This was the case in our study in May 2004, where positive linear correlations were found between MB and Cmin (correl. coef.=0.77; R 2 =59%) and between MB and LOM (correl. coef.=0.70; R 2 =49%). Results from October 2004 confirmed the previous observations, but with weaker relationships. On the contrary, Kemitt et al. (2008) concluded that the rate of humified organic matter mineralization is not necessarily proportional to the size, activity or composition of the microbial biomass. They hypothesized that the mineralization of organic matter is regulated by an abiological destabilizing process that transforms non-bioavailable substrates to bioavailable substrates.

Although microbial biomass is generally acknowledged to represent only a very small (0.1-5%) proportion of total carbon in the soil [START_REF] Robert | Interaction between soil minerals and microorganisms[END_REF][START_REF] Moore | Soil microbial biomass carbon and nitrogen as affected by cropping systems[END_REF], it is characterised by its rapid turnover compared to the other components of organic matter [START_REF] Sparling | Hot-watersoluble C as a simple mesure of labile soil organic matter: the relationship with microbial biomass C[END_REF]. This was in agreement with our results, where microbial biomass represented from 1.4 to 3.1% of total soil carbon. The size of soil C MB pool and its turnover have significant bearing on the overall productivity of soils. Labile organic C fractions (LOM) only account for a small fraction of soil organic matter (from 7.3 to 17.9% of total Corg in our study), but are used by the soil microbial community as an energy source for metabolic activity. The study of these fractions is important in agricultural soils, since they determine soil microbial activity [START_REF] Janzen | Light fraction organic matter in soils from long-term crop rotations[END_REF] and contribute to a structural function [START_REF] Metzger | Influence of sludge organic matter on soil physical properties[END_REF]. Labile organic matter pools can be considered as fine indicators of soil quality that influence soil function in specific ways and that are much more sensitive to changes in soil management practice [START_REF] Haynes | Labile organic matter fractions as central components of the quality of agricultural soils: an overview[END_REF]. In 2004, irrigation affected different Corg pools, while active organic carbon (MB and LOM) was slightly enhanced in the surface soil layer of IRR row (at downslope position).

The variations of the parameters related to the soil microflora are strongly influenced by the seasonal climatic trend [START_REF] Meli | Influence of irrigation with lagooned urban wastewater on chemical and microbiological soil parameters in a citrus orchard under Mediterranean condition[END_REF]. Comparing microbial biomass and activity between May and October, higher values of MB and Cmin were measured in May, especially in the year 2004 (Annex 9). In May, soil respiration increased probably due to the enhancement of microbial activity in soil. Following soil warming, microbes were more active, and decomposable organic matter from root exudation was produced in soil, providing abundant substrate available to micro-organisms, increasing both soil microbial biomass and respiration [START_REF] Ni | Study on respiration rate of soil microorganism on Aneurolepidium Chinese grassland of northeast China[END_REF].

The majority of the studies dealing with the impact of farming practices on microbial communities have shown that the spatial and temporal variability in microbial processes make this impact difficult to observe accurately [START_REF] Morris | Microbial biodiversity: approaches to experimental design and hypothesis testing in primary scientific literature from 1975 to 1999[END_REF]. Indeed, soil biological parameters are always the result of applied farming practices, spatial soil variability and weather conditions fluctuating both within (seasonal) and between years.

VII. Structural stability of soil aggregates

Structural stability was analysed twice: in October 2004 and in May 2005, with an interest to get information about irrigation impact on structural stability and seasonal changing of this parameter. At the first sampling date, irrigated and non-irrigated rows at all three positions of the slope (upslope, midslope and downslope) and at three depths (0-5, 5-15 and 15-30 cm) were studied (Tab. 3.25). Water stable aggregates (WSA) were measured after 2 and 6 hours of wetting. In May 2005, water stable aggregates were measured after 2 hours only and at two depths (0-5 and 5-15 cm) (Tab. 3.26). Indeed, a structural test was not performed on a large time scale till 12 to 20 hours afterwards, due to a large number of samples and due to suspecting differences in aggregating mode and not in textural differences (i.e. same type of soil).

VII.1 Variations of structural stability according to seasons

VII.1.1 October 2004

Gravimetric water content (W) at the time of sampling was performed systematically on each sample to take into account its influence on structural stability. W varied between 0.18 to 0.28 g.g -1 from upslope to downslope. Slightly higher gravimetric water content was obtained in the surface soil layer and no significant differences were observed between IRR and NIR rows.

WSA varied between 5 and 72 % after 2 hours and between 3 and 44 % after 6 hours, displaying wide range of variation. Large differences in WSA were noticed at midslope position. After 2 hours, higher structural stability was mostly found in the deepest soil layer with WSA values (39±19 % in average) statistically different (p=0.05) from the surface layers (25±18 %). Structural stability generally decreased from upslope to downslope, with two main patterns (Fig. 3.44a). The first pattern concerned IRR row and the surface layer of NIR row, where WSA upslope significantly differed from the two lower positions. The second pattern concerned NIR row in deeper layers. This showed high values of structural stability at upslope position, as well as at midslope position, while the lowest values were observed downslope. Generally, the highest structural stability appeared upslope (WSA=46±9 %) and it was significantly different from the two lower positions (WSA=29±24 % midslope and 21±8 % downslope). The most important observation is that IRR row had significantly lower structural stability (WSA=26 ±18 %) than NIR row (WSA=37±8 %) (Fig. 3.45).

Tab

Structural stability significantly decreased with duration of wetting. After 6 hours, WSA percentage generally decreased, with an average WSA of 32±18 % after 2h and 18±13 % after 6h (Fig. 3.44b). The effect of slope position still remained but there was neither the effect of depth nor irrigation status present (Fig. side effect could be relevant to tree planting system. Persistent cover of green algae on soil surface on the shady side was observed in the field. The discussion will present the 3 criteria (irrigation, slope and depth) and will also take in account the presumed effect of sun exposure. For this sampling date, only two soil depths (0-5 and 5-15 cm) were included in our study. In May 2005, gravimetric water content varied from 0.07 to 0.31 g.g -1 . The surface soil layer was significantly drier than sub-surface layer (0.17 and 0.28 g.g -1 respectively). Evident differences in soil moisture occurred according to slope position: upslope soils were the driest (W = 0.19 g.g -1 ) and differed significantly from midslope and downslope soils (W = 0.24 g.g - 1 ). According to treatment, W was similar in IRR and NIR rows (0.22 and 0.23 g.g - 1 respectively). No difference between shady and sunny site of the rows occurred, except in the surface layer, where W in the shady surface layer is higher than in the sunny surface layer (0.35 and 0.28 g.g -1 respectively). Comparing the two sampling dates down to 15 cm depth, W was more or less the same in spring than in autumn (0.22 and 0.24 g.g -1 respectively).

Tab

WSA varied between 11 and 57 %, which represents a wide range of variation. WSA increased significantly according to depth (31 and 44 % respectively). At midslope, WSA was higher (43 %) than at upslope (37 %) or at downslope (35 %), but this difference was not statistically significant. At upslope, very high and very low values were found, yielding a larger range of variation than at midslope and downslope positions. According to irrigation, there were no significant differences in mean WSA values (37 % in IRR and 39 % in NIR rows). The effect of sun exposure was noticed when considering only the surface soil layer (0-5 cm): WSA was higher on the shady than in the sunny side (35 and 28% respectively). However, it seems that both sun exposure and irrigation regime affect WSA: on the shady side, the effect of irrigation is less pronounced than on the sunny side (Fig. 3 Comparing two sampling dates, structural stability of soil aggregates was a bit higher in spring (37±16 % WSA in May 2005), compared to autumn (28 ±16 % WSA in October 2004).

VII.2 Discussion

Aggregation and aggregate stability are the result of an interaction of many factors including weather environment, soil management factors, plant influences and soil properties such as mineral composition, texture, soil organic carbon, pedogenetic processes, microbial activities, exchangeable ions, nutrient reserves, carbonates and moisture availability [START_REF] Bronick | Soil structure and management: a review[END_REF]. Climate and landscape position influence soil structure through factors such as temperature, precipitation, elevation, slope gradient, and aspect [START_REF] Bronick | Soil structure and management: a review[END_REF]. In the first place, soil structural stability is related to soil texture, especially to clay content [START_REF] Gollany | Aggregate stability on an eroded and desurfaced Typic Argiustoll[END_REF]. Another strong positive correlation was found between structural stability and soil organic matter [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF][START_REF] Goulet | Water-stable aggregates and organic matter pools in a calcareous vineyard soil under four soil-surface management systems[END_REF].

Topography was a strong soil developing factor in our study. Soils from upslope strongly differed to soil from downslope position. For this reason, certain field observations must be remembered prior to discussing structural stability: bedrock appearance, soil depth, soil colour and cracks observations according to slope. The soil from upslope was shallow (60 cm) compared to soil from downslope (more than 1 m). At upslope, the bedrock (marl) appeared already at 20 cm (as blocks), while at C horizon it appeared at 60 cm and downslope, it was the weathered saprolithe which appeared at 1 m. Differences along the slope occurred in soil colour as well: upslope soil was lighter (5Y 8/3) than downslope (10YR 7/3), suggesting a lower organic matter content at upslope position (probably due to erosion) and which was confirmed by organic carbon analyses.

On the samples from 2004, some correlations were studied between structural stability and the following parameters: Corg, clay and carbonates. In this analysis, complete results (from both water treatment and 3 depths) after two hours of wetting were included. From the figures (Fig. Here it has to be taken into consideration that particle size distribution has been performed without decarbonation which means a part of the clay content is here represented by particles of CaCO 3 and not by mineralogical clay and therefore does not play the same physical bonding role as mineralogical clays.

In Fig. 3.47c there are obviously two groups of soils according to WSA and CaCO 3 : one group at lower slope position and another at upslope. From different authors, it can be stated that: (a) topography by itself does not significantly affect macroaggregate stability [START_REF] Cantón | Aggregate stability in range sandy loam soils Relationships with runoff and erosion[END_REF]) but (b) higher SOM and clay content at downslope positions is reflected by higher aggregate stability [START_REF] Bricchi | The effect of topography, tillage and stubble grazing on soil structure and organic carbon levels[END_REF][START_REF] Eneje | Percent clay, aggregate size distribution and stability with depth along a toposequence formed on coastal plain sands[END_REF]Adanma, 2007, Le Bissonnais et al., 2002).

According to topography, sloping soils are more susceptible to erosion, particularly in regions of intensive rainfall. Erosion tends to preferentially remove low density or light particles including clay and SOC that are two of the primary bonding agents in aggregation [START_REF] Bronick | Soil structure and management: a review[END_REF]. This was not the case in our study, where structural stability at downslope position was lower despite higher SOM content. According to several authors [START_REF] Bronick | Soil structure and management: a review[END_REF][START_REF] Cantón | Aggregate stability in range sandy loam soils Relationships with runoff and erosion[END_REF], structural stability is in positive correlation with soil organic matter content. When observing relationships between structural stability and soil depth, a similar conclusion (as in the slope) about organic matter was made. Structural stability increased with soil depth (especially in IRR soils); even less SOM was present. In the literature, high structural stability in the surface soil layer was generally related to higher SOM content [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF]. However, increases in water stable aggregates are not always related to increases in SOM of a silt loam, which led [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF] to suggest that some components of SOM are more actively involved in soil aggregate stabilization than others. Another possible explanation for higher structural stability in deeper layer is SOM protection by CaCO 3 . There was a statistically significant relationship (at the 95% confidence level) between WSA and CaCO 3 in the surface soil layer. The R-Squared statistics indicate that the fitted model explains 70.5 % of the variability in WSA. In the surface soil layer, the equation of the linear fitted model to describe the relationship between WSA and CaCO 3 is the following with a correlation coefficient equals 0.84: %WSA = 2.6 + 2.7 * %CaCO 3 . At low SOC concentration, macroaggregate stability is enhanced by carbonates (Boix-Fayos et al., 2001). High carbonate concentration enhances SOC protection, probably through decreasing SOC mineralisation and increased Ca 2+ [START_REF] Clough | Physical and chemical protection of soil organic carbon in three agricultural soils with different contents of calcium carbonate[END_REF]. Upslope carbonate content was three times higher than downslope (16% versus 5%) (Fig. 3.47d), which could explain higher structural stability there. On steeper terrain, soil water content is lower, allowing a higher structural stability. This phenomenon is explained by the chemical precipitation of slightly soluble bonding agents at contacts points between soil particles [START_REF] Kemper | Soil cohesion as affected by time and water content[END_REF]. These bonding agents are gypsum, silica, or carbonates of calcium and magnesium [START_REF] Harris | Dynamics of soil aggregation[END_REF]. The precipitation of bonding agents at particle contact points as a consequence of drying is occurring in soils throughout the season, especially at upslope position.

Comparing water treatments, structural stability is in positive correlation with soil organic matter content and explains the difference in WSA between IRR and NIR. Structural stability evidently differed between IRR and NIR rows in the surface layer (WSA = 16 versus 28 %) which was probably a consequence of drip irrigation. Strong irrigation effect on structural stability was observed in October 2004 and it should be emphasized that in the season 2004, 30 days of irrigation was done (60 mm of added water), while results from spring 2005 were not related to irrigation. Lower SOM in IRR row soil could be explained by SOM mineralisation: IRR soils probably have more favourable conditions for microbial decay of SOM (lower C/N) and thus have lower SOM content at the time of sampling than NIR row. SOM input in IRR soils could be higher before sampling, but further microbial actions due to better soil conditions could change this initial situation. These results will be explained later with microbial biomass.

Structural stability is not a stable parameter, and several authors reported results of temporal changes in aggregate structural stability [START_REF] Brown | Seasonal trends in furrow irrigation erosion in southern Idaho[END_REF][START_REF] Lehrsch | Temporal Changes in Wet Aggregate Stability[END_REF][START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF]Yang end Wander, 1998). It is now well known that aggregate stability varies for some soils over a growing season [START_REF] Ellsworth | Temporal variations in soil structural properties under corn and soybean cropping[END_REF][START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF] or in longer periods [START_REF] Bullock | Soil cohesion as affected by freezing, water content, time and tillage[END_REF]. The majority of these studies have focused on the growing season [START_REF] Brown | Seasonal trends in furrow irrigation erosion in southern Idaho[END_REF][START_REF] Lehrsch | Temporal Changes in Wet Aggregate Stability[END_REF][START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF]Yang end Wander, 1998), although some information is also available on the influence of winter due to freezing and thawing processes [START_REF] Bullock | Soil cohesion as affected by freezing, water content, time and tillage[END_REF][START_REF] Coote | Seasonal variation of erodibility indices based on shear strength and aggregate stability in some Ontario soils[END_REF].

123

For this reason, a comparison in WSA between the beginning and the end of the growing season was done in our experiment. Comparing two studied sampling dates, the trend of structural stability was not the same. Higher WSA values were measured in May than in October. The pattern of structural stability according to depths were the same at autumn sampling, while in spring two soil layers showed differed trends: the surface layer had higher WSA at midslope , while deeper layer showed strong variability in the slope. This statement is in agreement with [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF] which reported a decrease of structural stability during the growing season although some authors reported different patterns of temporal variation in structural stability: [START_REF] Brown | Seasonal trends in furrow irrigation erosion in southern Idaho[END_REF] measured low structural stability in early spring, with a maximum in early summer. [START_REF] Lehrsch | Furrow erosion and aggregate stability variation in a Portneuf silt loam[END_REF] observed the maximum structural stability at the end of fall.

Many previous investigators pointed out the strong influence of soil water content at the time of sampling: in general, aggregate stability decreases with increasing water content. In our experiment, this pattern was found along the slope: downslope more humid conditions resulted in lower structural stability. Furthermore, moisture at sampling dates was in different correlation with structural stability: in autumn 2004 (Fig. 3.48a), low WSA percentage in humid soil conditions corresponds to significant negative correlation between W and WSA (r = -0.62 after 2 hours and r = -0.60 after 6 hours at p<0.05); while in spring 2005 (Fig. 3.48b), a positive correlation between W and WSA (r = +0.55 at p<0.05) occurred. The first relationship is in agreement with [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF] and [START_REF] Coote | Seasonal variation of erodibility indices based on shear strength and aggregate stability in some Ontario soils[END_REF], who found a significant negative correlation between soil moisture and WSA. [START_REF] Chan | Seasonal changes in surface aggregate stability under different tillage and crops[END_REF] reached a similar conclusion and asserted that seasonal variation in soil aggregate properties were significantly influenced by soil water content at the time of sampling. The second relationship explained that soil moisture content alone has no consistent effect on soil aggregate stability while soil moisture interacted with other factors to influence aggregation [START_REF] Yang | Temporal changes in dry aggregate size and stability: tillage and crop effects on a silty loam Mollisol in Illinois[END_REF]. The parameter of soil water content is not necessarily directly linked with water conditions in the sampling period, but can be masked with some other processes in soil (positive correlation between WSA and W might be only artificial, because it can be also affected by algae, not only by water content by itself). For this reason, gravimetric water content at the time of sampling was not a pertinent parameter for explaining structural stability. Anyway, the measure was done on air dried soils.

Changes of structural stability (WSA) may vary between years due to different climatic conditions: rainfall, temperature or frost occurrence. Variability of seasonal changing is mostly driven from rainfall or with soil water content [START_REF] Yang | Temporal changes in dry aggregate size and stability: tillage and crop effects on a silty loam Mollisol in Illinois[END_REF]. When relatively dry aggregates wet quickly by the advancing furrow stream, they are unstable [START_REF] Kemper | Soil cohesion as affected by time and water content[END_REF] and, upon disintegration, likely contribute to the high sediment loss rates. In our experimental location, heavy rains are typical and could contribute to lower structural stability in the surface layer with possible surface crusting (Le Bissonnais and Arrouays, 1997). In our study, winter 2004/05 was dry (280 mm rainfall from Nov. 2004 till May 2005) compared to the 30-year average (465 mm). This data could be also important for explaining higher structural stability in spring. [START_REF] Unger | Overwinter changes in physical properties of no-tillage soil[END_REF] pointed out the importance of soil physical properties over a relatively cold but dry winter, while over a wetter winter he detected a decrease of structural stability. The freezing and thawing process may be responsible for the changes in aggregate stability occurring during winter [START_REF] Chan | Seasonal changes in surface aggregate stability under different tillage and crops[END_REF]. Weather conditions probably influenced marl behaviour and as a consequence higher structural stability at midslope position (in spring 2005). Differences in structural stability according to slope between October 2004 and May 2005 were presumably related to special behaviour of bedrock during the year (temperature, soil moisture). In dry conditions, more vertical cracks appeared and structural stability was stronger compared to wet conditions. Some conclusions from both sampling date were confirmed for our study site:

1. Large range of variation of the structural stability was noticed in space (at the slope scale) and in time (according to water conditions during the season). 2. Structural stability was positively correlated with soil calcium carbonates content. 3. Structural stability was not always positively correlated with soil organic matter content. 4. Water content at the sampling date was not a pertinent parameter (and justifies the normalised methods working on air dried soils). 5. According to sun exposure, structural stability in the surface layer was higher at shady side of the rows (which could explain positive relation with soil moisture in May 2005).

VIII. Discussion and conclusions -Gačnik site

The study field in Gačnik was very heterogeneous due to rough human intervention to soil reorganisation and topography. For this reason, the results were sometimes masked or not as representative as expected in an ideal situation. Anyway, our study was a good opportunity to learn how to study soil behaviour in the field according to irrigation and how to approach the real situation in practise.

Regarding the hilly terrain and land levelling, we were dealing with two groups of soil: one at upslope and another one at mid and downslope. Considering soil characteristics, slope effect was more expressed than irrigation effect. Lower gravimetric water content in irrigated row could be explained by the modification in root distribution and development due to drip irrigation. According to Isbérie (1995), drip irrigation may favour a specific distribution of the root system, more superficial around the dripper. This distribution may favour drier superficial soil after irrigation due to root system water extraction. Moreover, this drier water regime may favour higher porosity in these loamy clay soils. The influence of drip irrigation on root system distribution may be rapid, especially in young plantation.

In our study, irrigation differently affected soil organic matter considering time periods. Supplementary drip irrigation increased microbial biomass and its activity (short time effect) but gently decreased total SOM content and structural stability (long time effect). Indeed mineralization processes, as shown by lower C/N ratio of SOM and higher respiration (Cmin), are more intensive in IRR soil, with lower remaining SOM in this treatment. Previous statements were supported by several authors. [START_REF] Kochsiek | Impact of managment on decomposition and the litter-carbon balance in irrigated and rainfed no-till agricultural systems[END_REF] and [START_REF] Mandal | Evaluating impact of irrigation water quality on a calcareous clay soil using principal component analysis[END_REF] reported that irrigated management regimes not only led to greater litter-C inputs but also greater decomposition rates. According to grain size fraction, only fraction A showed significant difference in Corg between IRR and NIR rows in favour of irrigation. Fraction A is an important indicator of the SOM quality, which was in agreement with [START_REF] Christensen | Physical fractionation of soil and structural and functional complexity in organic matter turnover[END_REF]. This could explain lower organic matter content in irrigated row. Because mineralization is performed by the microbial biomass, it is often assumed that this process is at least partly regulated by its size, specific activity or composition [START_REF] Marschner | Controls of bioavailability and biodegradability of dissolved organic matter in soils[END_REF][START_REF] Fontaine | Size and functional diversity of microbe populations control plant persistence and long-term soil carbon accumulation[END_REF]. Contents of total and labile organic matter and microbial biomass are significantly affected by different irrigation regimes, while drip irrigation increases microbial biomass [START_REF] Han | Effect of Different Methods on Dissolved Organic Carbon and Microbial Biomass Carbon in the Greenhouse Soil[END_REF][START_REF] Melester | USDA-ARS, 94 th ESA annual meeting[END_REF][START_REF] Samuelson | Soil and microbial respiration in a loblolly pine plantation in response to seven years of irrigation and fertilization[END_REF][START_REF] Entry | Influence of irrigated agriculture on soil microbial diversity[END_REF][START_REF] Martiniello | Biochemical parameters in a Mediterranean soil as affected by wheatforage rotation and irrigation[END_REF]. Management practices of irrigated land, including yearly organic fertilizer application or (indirectly) through grass in inter-rows, result in the addition of young, labile OM to irrigated soil which contributes to the mineralization of organic N. The labile OM acts as a substrate for microorganisms and is readily decomposed, turning over large amounts of N. However, the total organic matter content of the irrigated treatment did not increase. Constant OM levels, increased mineralization, relatively high NO 3 -N levels, and increased uptake of available N in the irrigated treatment stress the importance of OM quality.

The rapid cycling of OM in irrigated soils results in increased plant uptake of readily available nutrients and greater soil fertility [START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF].

Organic matter reduction is, in turn, associated with the soil structure degradation [START_REF] Albiach | Organic matter components and aggregate stability after the application of different amendment to a horticultural soil[END_REF][START_REF] Mandal | Evaluating impact of irrigation water quality on a calcareous clay soil using principal component analysis[END_REF], which was also found in our study. Improvement of soil structure through organic matter input has been found to be of primary importance in the type of soil on which the study was conducted. Soil structure had high susceptibility to degradation by the action of water or tillage despite the fact that these soils have more than 50% total porosity [START_REF] Gomez | Changes in some soil properties in a Vertic Argiudoll under shortterm conservation tillage[END_REF]. Irrigation results in aggregate destabilization either through rapid organic matter (OM) breakdown and mineralization, or continuous years of water-drop impact. In our study, the results of soil structural stability according to irrigation confirmed the previous statements.

Among chemical properties of irrigation water, only the amount of nitrates was high, which probably contributed to higher mineral nitrogen values in IRR soils. The significant difference of NO 3 -N levels in IRR row may be attributed to greater mineralization of N in irrigated land than dryland [START_REF] Henry | Evaluation of the Effects of Irrigation on Soil Chemical and Physical Properties. Irrigation sustainability -Saskatchewan activity[END_REF]. Before explaining structural stability results according to slope and depth, emphasis needs to be placed on decreasing of soil organic matter and increasing of carbonates towards upslope and with depth. As mentioned before, high structural stability is related to the organic matter content [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF]. However, in our study, SOM was negatively related (r = -0.89) to structural stability according to slope and depth (Fig. 3.49).

Fig. 3.49:

Correlation between structural stability (WSA) and total OC stock (T.ha -1 .cm -1 ).

*Data of WSA from 15-30 cm in NIR row at midslope position (72 %) was excluded from the correlation due to strong standard deviation.

This was explained by [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF], who suggested that some components of organic carbon pool are more actively involved in stabilizing aggregates than others and total organic carbon is not necessary positively linked with WSA. A specific fraction of the organic pool may be the main stabilizing agent (Roldan et al., 2003), and therefore the measurement of total organic carbon content may not be sufficiently discriminating [START_REF] Janzen | Light fraction organic matter in soils from long-term crop rotations[END_REF]. In our study we were dealing with different pools of organic matter: (a) young organic matter from trees and microbial biomass and (b) sedimentary organic matter from the weathering of the marl bedrock. To accertain the respective role of these two fractions, correlations between structural stability and fresh or sedimentary OC stock was studied. Clear negative correlation between fresh OC and WSA (Fig. 3.50a) and no relation between WSA and sedimentary OC (Fig. 3.50b) were found. Therefore, we can assume that sedimentary OC didn"t have an effect on structural stability.

Total OC stock (T.ha *Data of WSA from 15-30 cm in NIR row at midslope position (72 %) was excluded from the correlation due to very high standard deviation.

But anyway, fresh OC still displayed an even more negative correlation to structural stability which remains unexplained. The answer may lie in the positive correlation between WSA and carbonates, even if it was not very strong (Fig. 3.51). High percentage of total carbonates in soil could also contribute to higher structural stability through protecting SOM from mineralization. It is generally accepted that calcium is a critical element for stabilization of SOM and aggregates [START_REF] Six | A history of research on the link between (micro)aggregates, soil biota, and soil organic matter dynamics[END_REF], inducing higher structural stability in soil samples with high carbonate content. Soils from our study had a great potential to contain high content of protected SOM due to a large proportion of fine particles: 45-50% clay and 25-35% fine silt. A positive correlation between WSA and CaCO 3 (r = +0.52) was determined (Fig. 3.51).

Fig. 3.51:

Correlation between structural stability and total carbonates (CaCO 3 ) stock (T.ha -1 .cm -1 ).

After discussing different types of OC, there is still one hypothesis which can help interpret lower organic matter content in irrigated row. In fraction C, which is the dominant fraction in whole bulk soil, sedimentary OC represented about a half of total organic carbon (Fig. 3.52).

When comparing IRR versus NIR sites by pairs, they showed similar sedimentary OC stocks, except downslope for fraction A where the very high sedimentary stock was attributed to a possible presence of sand size particles of marl, and fraction C at midslope and downslope. It could be explained by the higher microbial biomass and activity in irrigated row. Microbes may attack sedimentary organic matter and this could explain lower TOC value there. Mineralisation of sedimentary OC is very important in relation to general cycle of organic carbon by producing additional CO 2 , going to atmosphere. Organic matter, which is entrapped in geological substratum (marl) may be mineralised by irrigation process, which has to be taken into account according to the environmental point of view. At upslope, the amount of sedimentary OC in both treatments was more or less the same, which gives some doubts about arriving irrigation water to this point.

Fig. 3.52: Distribution of fresh (white) and sedimentary (coloured) OC stock (T.ha -1 .cm -1 ) according to fraction, slope and treatment.

Soil structural stability is not a constant parameter; it is changing within season and between years. Structural stability variation with moisture content may be due to sampling, physicochemical, or biological factors [START_REF] Perfect | Factors Influencing Soil Structural Stability within a Growing Seasons[END_REF]. For this reason, reliable assessment of structural stability should not rely only on one time measurement. Additional research will be needed to pinpoint the mechanisms of structural stability and its temporal changes according to irrigation. Seasonal variations of structural stability are difficult to explain with soil water content only, however rainfall and microbial biomass information could be helpful. In our study, higher structural stability was measured in spring 2005 than in autumn 2004. An explanation for this result might be the dry winter 2004/2005, as previously observed by [START_REF] Unger | Overwinter changes in physical properties of no-tillage soil[END_REF]. Another explanation of higher structural stability in spring 2005 is the higher microbial biomass in this period. In the surface soil layer, a strong positive correlation between WSA and soil moisture was found (r=0.93 with double reciprocal model: WSA = (-0,0035 + 0,64/humidity) -1 ), which could probably be explained by the presence of green algae on the shady side, where WSA and soil moisture were higher. Contribution of microorganisms to soil aggregate stability is a well-known phenomenon. Microbial biomass has been reported as responsible for soil aggregation [START_REF] Gupta | Distribution of microbial biomass and its activity in different soil aggregate size classes as affected by cultivation[END_REF], but relationships between soil microbial biomass and aggregate stability are not very consistent and tend to be mainly site-specific (Carter et al., 1999). Two major mechanisms are suggested by [START_REF] Lynch | Microorganisms and structural stability-Advances in soil sciences[END_REF]: the ability of some micro-organisms, mostly filamentous, to mechanically bind soil particles, and the production of binding agents by some others (bacteria). In general, fungi are reported to be the most effective in soil aggregation [START_REF] Lynch | Microorganisms and structural stability-Advances in soil sciences[END_REF]. In the end, some doubts still remain about irrigation practice: a) if enough irrigation in one season was done to measure its actual (short-term) impact; b) if enough seasons of irrigation was performed to study long-term effect of irrigation; c) if irrigation was really needed in this type of soil; d) if irrigation water really reached upslope in the same amount as downslope; e) if sampling was reliable to compare irrigated versus non-irrigated soils?

In 2004, only 30 days of irrigation were performed, which was more than twice less than one season before (70 days). The irrigation effect we measured in our study was the consequence of only a few previous irrigation seasons. Before 2004, 6 years of irrigation were performed, which could participate to changes in soil properties. This time period is long enough to modify the root system of young plantation and therefore modify water regime at soil surface and keep a long term effect even without irrigation.

According to the soil texture in our study, irrigation is not the most recommended practice. Such soils are susceptible to structural damage, if they are intensively cultivated [START_REF] Kostopoulou | The effect of soil water content and microbial activity on restoring the structure of a vertisol[END_REF]. The fine silt fraction could contribute soil sealing. A good interpretation of irrigation effects should include additional information about the changes in porosity redistribution and the break of water circulation channels in the soil profile (Ramoz et al., 2007). Regarding significantly lower soil humidity at upslope, it might have happened that in irrigation pipes there was not enough pressure to push water to the top of the hill. For a reliable study, it could be useful to compare the treatments (IRR versus NIR) on several rows and not on only one row for each treatment. In our case, the situation has been already settled in manner way for six years and used by us as a preliminary study.

Conclusions

1. Soils along the slope were very heterogeneous due to land and soil reorganisation. 2. Slope effect had much stronger effect on soil quality than irrigation. According to slope, we were dealing with two groups of soil: one at upslope and another one at mid and downslope. 3. Supplementary drip irrigation gently decreased total SOM content and structural stability (long time effect), but increased microbial biomass and its activity (short time effect). 4. A high percentage of total carbonates in soil contributes to higher structural stability. 5. Higher structural stability is not always explained by higher total organic matter content, which was found according to slope and depth. 6. Information from isotopic composition of carbon ( 13 C) can be a successful tool for distinguishing different pools of organic matter, namely fresh and sedimentary organic matter. 7. Structural stability is not a constant parameter; it is changing within season and between years. For this reason, a serious assessment in structural stability should not rely only on one time measurement. 8. For improving structural stability in irrigated soils, adding organic fertilizers probably would be helpful. 9. Basic chemical parameters in irrigation water should be regularly monitored to avoid structural breakdown and soil pollution with nitrates.

Chapter 4

Results in Pohorski dvor Chapter 4: Results in Pohorski Dvor

The study in Pohorski dvor is dealing with the possibility of enhancing microbial biomass and nitrogen nutrition with different combinations of organic fertiliser and liming. Among different applied organic fertilisers, Compo guano was chosen as a reference fertiliser due to its high nitrogen content (11% N).

For a better understanding the results of our study, it is very important to describe morphological properties of soils first and represent soils in general. Two pits were dug and soil morphology in the inter-row space in blocks I (laying at downslope) and III was described for this purpose (Tab. 4.1).

I. Soil morphology

For a simple characterisation of soil properties in the study area, two soil pits were dug in inter-row space in blocks I and III (where tensiometers were settled). A simple description of some morphologic soil properties are presented in Table 4.1. There was rather important soil heterogeneity in this orchard in relation to the shape of the slope. An obvious difference occurred between block I and block III. Compare to block III, soil from block I was more humid, loam texture was observed till deeper layer, fine granular structure was observed in the shallower part of the soil, consistence became compact from 10 cm of depth onwards and the colour had the appearance of hydromorphic features from 50 cm. In block III, soil colour indicated more SOM and a lot of weathering material were noticed in the soil profile (mica from schist).

Tab.

II.2 Soil pH evolution according to treatment and year

For interpreting microbial parameters, soil pH (in water and in KCl) was measured in parallel with microbial analysis (during two seasons). In May 2004, no significant differences in pH KCl occurred according to the treatments (combinations of Compo guano and lime) and according to soil depth (Fig. In November 2004, differences occurred between treatment 5 (pure control-no Compo guano, no lime) and 6 (Compo guano + lime): liming increased significantly soil pH (Fig. 4.2). For these two treatments, pH values were quite similar in both soil layers. In May 2005, more significant differences were observed: treatment 5 (pure control) and treatment 1 (Compo guano without lime) had similar pH values, but they significantly differed from treatment 10 (lime only) which exhibited a higher pH value in the upper layer (Fig. 4.3). Treatment 6 (Compo guano + lime) significantly differed from all the other treatments with the highest pH value. In general, Compo guano decreased soil pH, while liming increased soil pH. The upper soil layer showed significantly higher pH values compared to the deeper layer. Changes mostly occurred in the upper soil layer, which was expected because fertilisers and lime were incorporated till this depth.

II.3 Discussion

The soil of our experimental field was very heterogeneous according to physico-chemical properties. Significant differences occurred mostly between block I and block III or even among all three blocks. Block I had the lowest sand and the highest silt percentage, the lowest P 2 O 5 and the highest CEC and pH. Block III had the highest sand and the lowest silt and clay percentage, the lowest Corg, Norg and CEC and the highest P 2 O 5 . Block II had the highest clay content. A slight decrease of clay and Corg content in direction from block III to block I could probably be explained by erosion process along the slight (5%) slope, block I being settled at downslope position. pH KCl in block I (5.2) was higher than in the two other blocks (4.6 in block II and 4.7 in block III). Even when properly mixed with soil, lime has little effect on pH if the soil is dry. However, only one application was done before sampling, so it"s difficult to explain some differences as a real consequence of organic fertilising and liming in such short period.

pH was measured along both seasons of the experiment, so temporal distribution of this parameter is represented in Fig. 4.5. Treatments with liming slightly increased soil pH (Fig. 4.5). The strongest effect on soil pH was observed for the treatment 10 (lime without Compo guano), for which all pH values increased during the experiment. The immediate reaction between soil and lime lead to an immediate increase in pH of the soil water due to partial dissolution of carbonates [START_REF] Ola | Geotechnical properties and behavior of some stabilized Nigerian lateritic soils[END_REF]. However, the completion of the reaction is slow and their effect may show up in days, months, or years [START_REF] Ola | Geotechnical properties and behavior of some stabilized Nigerian lateritic soils[END_REF].The same pattern was observed in the treatment 6 (Compo guano with lime), but the values were somewhat lower. Benefits of compost amendments to soil also include pH stabilization and faster water infiltration rate due to enhanced soil aggregation [START_REF] Stamatiadis | Assessment of soil quality as affected by compost and fertilizer application in a broccoli field (San Benito County, California)[END_REF]. In the treatments without liming, Compo guano alone induced lower soil pH values comparing to treatments 6 (Compo guano with lime) and 10 (lime only).

III Physical soil characteristics

Soil temperature

Soil temperature was measured at 5 cm of depth at the sampling date. Soil temperatures were more or less the same for all the studied area: 12.5 • C (standard error: 0.1 • C).

III.1 Soil water characteristics

III.1.1 Soil water retention curve (SWRC)

Water retention curve was done in soils from pure control (treatment 5) in two blocks: block I and block III. Both curves were done at 6 pressure points: 33, 100, 200, 300, 500, 1000 and 1500 kPa for three depths separately (20-25, 40-45 and 80-85 cm). 20-25 46.8 41.86 34.72 34.33 25.45 24.45 23.31 22.62 19.34 19.47 19.75 17.38 40-45 46.15 46.69 33.66 38.02 23.83 28.43 21.86 26.23 17.19 23.12 16.74 21.79 80-85 58.10 44.92 44.43 39.42 31.80 26.51 28.97 25.18 24.52 21.47 26.75 19.81 θ (cm3.cm -3 ) = volumetric water content Generally, in block I, volumetric water content was higher than in block III (Tab. 4.4).

In block I, the values of volumetric water content were higher in the deepest layer (80-85 cm), while in the upper layers ( 20 The previous results were used to calculate the available water content (AW). The deepest layer contains the highest value of available water (31 cm 3 .cm -3 ) in block I, compared to upper layers (29 cm 3 .cm -3 in 40-45 cm and 27.05 cm 3 .cm -3 in 20-25 cm layer). Similar situation occurred in block III, but here the differences in available water content were very small: 25 cm 3 .cm -3 in 80-85 cm, 25 cm 3 .cm -3 in 40-45 cm and 24 cm 3 .cm -3 in 20-25 cm layer. In June 2004, 232 mm of rainfall was measured, 98 mm in July, 77 mm in August and 99 mm in September. One main minimum of rainfall was noticed: in the beginning of August, where the lowest water potential was measured, mainly in the upper soil layer (20-25 cm).

In block I, water potential measurements in soils from all treatments soils (treat. 5-pure control, 10-lime only and inter-row) were very similar till the last rainfall in June. In July, water potential in treatment 5 (pure control) decreased more intensively, especially in the two upper layers (20-25 and 40-45 cm), and in the beginning of August the lowest value was reached. In this minimum water potential peak differences were observed according to treatments. In treatment 5 (pure control), water potential values in upper soil layers were very similar, while in the deepest layer the highest water potential was measured. In treatment 10 (lime only), a large difference between the deepest and the shallowest soil layers was noticed: the highest water potential was measured in the deepest layer and the lowest in the shallower layer. In the soil from inter-row, the sub-surface soil layer showed a value of water potential lower than for deeper layers, where similar measurements were observed. Later, values from all three soil layers followed rainfall simultaneously. Soil from inter-row showed higher water potential compared to soils from the rows. In soil from treatment 5 (pure control), the lowest water potential was measured compared to treatment 10 (lime only).

In block III, water potential measurements were similar till the last rainfall in all treatments and layers. Later, water potential decreased more rapidly in treatment 5 (pure control) like in block I, especially in the sub-surface soil layer. The pattern of decreasing water potential was very similar in treatments 5 (pure control) and 10 (lime only): the deepest soil layer had always the highest water potential and the sub-surface the lowest water potential. A difference occurred in the minimum peak in the beginning of August, when one week delay in the deepest soil layer in treatment 10 (lime only) was noticed. The two upper layers showed more or less the same values. Rainfall in the second half of July induced an increase of water potential in all three layers. Further differences among soil layers were more obvious in treatment 10 (lime only). In the inter-row, the highest water potentials were measured compared to the two other treatments (5-pure control and 10-lime only).

III.2 Evolution of gravimetric water content according to treatment and year

Significant differences in water content were noticed among blocks in both soil layers, where block I showed the highest soil moisture and block III the lowest soil moisture (Fig. 4.9). In October 2004, no effect of treatments was observed, while upper soil layer contained significantly higher soil moisture (Fig. 4.11). In May 2005, a significant difference was found between treatment 5 (pure control) and 10 (lime only), liming slightly decreasing gravimetric water content (Fig. 4.12). No differences were observed according to depth. In October 2005, no differences in gravimetric water content were noticed according to treatments and depth (Fig. 4.13).

III.3 Discussion

Significant differences in gravimetric water gradient occurred among blocks: block I had the highest soil moisture and block III the lowest. Beside some physico-chemical properties (like slightly higher % clay and SOM), this was probably also due to the slope gradient (5 %), block I being located at the lowest position. Slightly lower values of soil moisture were observed in case of liming. Liming decreased gravimetric water content probably through the improvement of soil structure and this could affect pore space in sense of better water drainage. It is already known that liming improves soil structure [START_REF] Mclean | Potentially beneficial effects from liming: chemical and physical[END_REF].

Comparing the slope of water retention curves from different soil layers, the deepest layer (80-85 cm) exhibited a more pronounced slope in block I, i. e. it contained the largest amount of available water. In block III, the deepest layer contained intermediate values of volumetric water content, but the highest amount of available water. Soil from block I had a finer texture than in block III, contributing to more humid conditions. Morphological observations detected hydromorphic features in deeper soil layer in block I. Soil in block I was also more compact due to polyedric structure. Some differences occurred in pattern of water potential measurements in different treatments and blocks according to dry periods. Water potential very clearly followed the rainfall distribution. However, comparing water potential curves in blocks I and III, water potential measurements were higher in block I (more humid soils). Comparing water potential curves in different soil layers in both blocks, the sub-surface soil layer (20-25 cm) showed the biggest variation. Soil from the deepest soil layer (80-85 cm) had the highest water potential compared to soils from upper layers, especially in dry periods (appearance of hydromorphic features in block I). Soil from inter-row showed higher water potential compared to soil from The lowest water potential was measured in soil from treatment 5 (pure control), compared to treatment 10 (lime only). A possible explanation could be the better structure in treatment 10 (lime only), due to liming, which allowed easier water movement through the soil profile and less water stagnation. Moisture is essential for the lime-soil reaction to occur. Significant increase of pH was noticed in the block I, where pH KCl was higher (5.2) compared to blocks II and III (4.6 and 4.7 respectively). Even when properly mixed with soil, lime will have little effect on pH if the soil is dry (http://www.herbgardeningguru.com/soil-ph.html), so this could explain the higher pH observed in block I.

IV Microbiological soil parameters evolution according to treatments and seasons

As basic microbiological properties, microbial biomass (BM), labile organic matter pool (LOM) and mineralised carbon from microbial respiration after 28 days (Cmin) were determined. Complete measurements of microbial parameters are presented in Annex 11 (in 2004) and in Annex 12 (in 2005).

IV.1 May 2004

Microbial biomass (BM)

In May 2004, no differences in microbial biomass were detected according to the treatments. Microbial biomass was significantly lower in deeper layer (Fig. 4.14).

Labile organic matter pool (LOM)

LOM was determined in the upper soil layer only. No differences according to treatments were noticed (Fig. 4.15).

Cmin

Cmin, released by microbial respiration, showed no significant differences according to treatments, while a slight increase of Cmin was noticed in the treatment 10 (lime only). The effect of liming with Compo guano was not clear due to their interaction. Cmin significantly decreased with depth. In treatment 6 (Compo guano with lime), the most intensive respiration of soil microbes was detected (Fig. 4.16 and Tab. 4.5). In the upper soil layer, the effects of the treatments were more pronounced, inducing larger differences in soil respiration than in the lower layer.

Tab. 4.5: Spec. respiration (day -1 ) and time of turnover (day); Pohorski dvor, May 2004.

Distribution of soil organic matter components in total Corg

In Fig.

IV.2 September 2004

Microbial biomass (BM)

In September 2004, microbial biomass did not significantly differ according to the treatments; only a slight increase in the treatment 10 (liming without Compo guano) was noticed (Fig. 4.18). The upper soil layer contained significantly more microbial biomass.

Compo guano, no lime

Compo guano, lime

Labile organic matter pool (LOM)

In September 2004, LOM didn"t differ significantly according to treatments (Fig. 4.19).

Cmin

In September 2004, statistical significant differences occurred regarding the released CO 2 from microbial respiration: more Cmin was detected in treatment 1 (Compo guano without lime) compared to treatment 5 (pure control). Compo guano contributed to higher microbial respiration. Without Compo guano, liming still increased Cmin, while in combination with Compo guano the opposite effect was observed (Fig. A significant difference was observed for specific respiration, which was lower in treatment 5 (pure control) than in treatment 1 (Compo guano without lime). No differences according to depth were noticed (Tab. 4.6).

IV.3 May 2005

Microbial biomass (BM)

In May 2005, significant differences occurred for microbial biomass: (a) between treatment 1 (Compo guano without liming) and treatment 6 (Compo guano with liming); (b) between treatment 1 (Compo guano only) and treatment 10 (liming only). Liming obviously contributed to higher values of microbial biomass (Fig. 4.21).

In the upper soil layer significantly higher microbial biomass was observed.

Cmin

In May 2005, no significant differences according to treatments were noticed. From the Fig. In May 2005, a significant difference occurred between treatments 10 (lime only) and 1 (Compo guano without liming), where liming increased specific respiration (Fig. 4.23 and Tab. 4.7). No differences according soil depth were observed.

IV.4 September 2005

Microbial biomass (BM)

In September 2005, a statistically significant difference in microbial biomass occurred between treatment 5 (pure control) and treatment10 (lime only), with lower values for liming. Microbial biomass also significantly decreased with soil depth (Fig. 4.24).

Labile organic matter pool (LOM)

In September 2005, LOM didn"t differ significantly according to treatments, but we still could notice a low LOM value due to liming without Compo guano (Fig. 4.25).

Cmin

No significant differences in Cmin were observed among the treatments, but it could be noticed that liming generally stimulated C mineralisation (Fig. 4.26 and Tab. 4.8). Significantly higher Cmin was detected in the upper soil layer, where specific respiration was also the highest.

IV.5 Discussion

At the beginning of the experiment (spring 2004), values of BM, LOM and Cmin were uniform among blocks, while after applied treatments (autumn 2004), the lowest values of these parameters were found in the block III. Microbial parameters in this block were in accordance with the lowest Corg and the lowest available water content. Humidity and organic matter could be limiting factors of microbial biomass and activity here.

In May 2004, microbial biomass, LOM and released Cmin from microbial respiration were not significantly affected by treatments yet (after just one application of fertiliser and lime).

Lime alone slightly increased C mineralisation and part of active Corg, while in combination with Compo guano the effect was unclear, presumably due to interactions between the organic amendment and liming. Compo guano slightly contributed to faster mineralisation process, increased LOM and more active Corg in the upper layer.

In September 2004, treatments did not affect microbial biomass significantly, but a slight increase of BM for liming without Compo guano was still noticed. Significant differences in Cmin occurred, where Compo guano alone increased values of released CO 2 . Compo guano stimulated soil respiration as well. Liming or Compo guano alone stimulated C mineralisation, but not in combination (unclear effect due to their interaction). In September 2004, LOM did not differed significantly according to treatments. This was expected while LOM usually do not change over short periods.

In May 2005, liming had a positive effect on microbial biomass and a negative effect on LOM, due to previous stimulation of C mineralisation. However, there was no extra input of Corg in the treatment 10 (lime only), so LOM was decreasing due to accelerated SOM turnover. LOM was presumably consumed more intensively by microbial biomass.

In September 2005, a slight decrease of BM in case of liming was probably a consequence of the observed decreased of LOM in May 2005. Low values of LOM occurred probably due to more intensive C mineralisation, leading to less microbial biomass.

Liming alone had a positive short-term effect on BM, but on the cost of lower LOM after intensive respiration. During the longer period, liming alone decreased both BM and LOM. Anderson (1998) also found that the microbial activity measured as basal respiration was higher after liming as compared to the control, and [START_REF] Kreutzer | Effects of forest liming on soil processes[END_REF] noticed that the C pool of the organic surface layer and upper mineral soil decreased (root biomass not included) after long lime application. In the combination with Compo guano, unclear effect on BM, LOM and Cmin was found due to their interaction.

Generally, Compo guano contributed to more intensive microbial respiration and to small increase of active Corg. In general, the addition of compost and amendment applications stimulated microbial respiration (Gonzales, 2010;[START_REF] Marinari | Influence of organic and mineral fertilisers on soil biological and physical properties[END_REF]. Most of the carbon supplied by this amendment is partially decomposed material, easily degradable and used as energy and nutrient source by soil microorganisms, resulting in an increased soil microbial respiration [START_REF] Stevenson | Cycles of Soil Carbon Nitrogen Phosphorus Sulfur Micronutrients[END_REF].

It is well known that biomass increases when organic materials are applied to soil [START_REF] Jenkinson | Microbial Biomass in Soil: Measurement and Turnover[END_REF]. While organic amendments generally increase BM [START_REF] Mazzarino | Dynamics of soil total C and N, microbial biomass, and water-soluble C in tropical agroecosystems[END_REF][START_REF] Goshal | Effects of farmyard manure and inorganic fertilizer on Dynamics of soil microbial biomass in a tropical dryland agroecosystem[END_REF], there are diverse reports regarding the effect of mineral N fertilizers on the size and activity of soil microbial biomass. In our experiment, Compo guano alone did 155 not significantly increase BM, probably due to low soil pH. Application of organic fertilizer as well as various composts generally caused an increase in microbial populations compared to mineral fertilizer, but the patterns varied depending on the type of organic fertilizer [START_REF] Krishnakumar | Microbial population and enzymatic activity as influenced by organic farming[END_REF], application rate [START_REF] Lee | Effect of food waste compost on microbial population, soil enzyme activity and lettuce growth[END_REF][START_REF] Mondini | Soil application of meat and bone meal. Short-term effects on mineralization dynamics and soil biochemical and microbiological properties[END_REF], soil type to which it was applied [START_REF] Perez-Piqueres | Response of soil microbial communities to compost amendments[END_REF] and the time scale of investigations [START_REF] Kokalis-Burelle | Changes in populations of soil microorganisms, nematodes, and enzyme activity associated with application of powdered pine bark[END_REF]. In some cases, compost or farmyard manure did not significantly enhance any microbial density more than mineral fertilizer [START_REF] Lalfakzuala | The effects of fertilizers on soil microbial components and chemical properties under leguminous cultivation. -Am-Euras[END_REF]. This result also showed that the effect of the organic fertilizer on microbial populations was not always the same or consistent over the whole season [START_REF] Lee | Effect of application methods of organic fertilizer on growth, soil chemical properties and microbial densities in organic bulb onion production[END_REF].

Obviuosly, at Pohorski dvor, where soil pH is low, the effects of addition of organic matter on soil metabolism are mitigated by soil pH. It must be pointed out that Compo guano alone increased soil acidity. The effects on labile pools of OM (BM and LOM) are therefore different for limed or unlimed situations. In combination with liming, Compo guano contributed to higher nitrate values. From Fig. 4.28 it can be seen that BM increased during the experiment, following the addition of fertiliser or lime (as observed for soil pH). The best combination was Compo guano with lime (only in the second season); being an easily available source of Corg, Compo guano increased BM while lime avoided excessive soil acidification which is detrimental to soil organisms. Liming was more efficient in the upper soil layer (positive effect on soil pH).

Generally, nitrate values were very low. Possible explanations could be: (1) the soil was very wet and nitrates could be leached or (2) mineralisation was disturbed due to excessive soil moisture and low pH or (3) due to denitrification. Compo guano contributed to the highest nitrate values when in combination with liming. [START_REF] Gunapala | Dynamics of soil microbial biomass and activity in conventional and organic farming systems[END_REF] also reported a positive effect of improved conditions for microbial life on soil nitrogen in fields under organic production.

Cropping history, type of plant cover, plant age, and climatic changes are also well known to influence soil microbial biomass and its activity, thus leading to considerable seasonal fluctuations in BM [START_REF] Franzluebbers | Seasonal changes in soil microbial biomass and mineralizable C and N in wheat management systems[END_REF][START_REF] Xu | Above and below ground transformation of Photosynthetically fixed carbon by two barley (Hordium vulgare L.) cultivars in a typic cryoboroll[END_REF][START_REF] Mendes | Microbial biomass and Activities in soil aggregates affected by winter cover crops[END_REF][START_REF] Moore | Soil microbial biomass carbon and nitrogen as affected by cropping systems[END_REF][START_REF] Piao | Seasonal changes of microbial carbon related to climatic factors in soils from karst areas of southwest China[END_REF]. However, only a few long-term field studies exist to ascertain the practical significance of these fluctuations on crop growth and nutrient cycling [START_REF] Kaiser | Seasonal variations of soil microbial biomass carbon Within plough layer[END_REF][START_REF] Joergensen | Time-course of the soil microbial biomass Under wheat; A one year field study[END_REF][START_REF] Goshal | Effects of farmyard manure and inorganic fertilizer on Dynamics of soil microbial biomass in a tropical dryland agroecosystem[END_REF]. The temporal trend of C availability, soil microbial biomass and its activity could be much more pronounced as compared to treatment effects. Treatment effects on BM could be also associated with temporal variations in the microbial community structure.

V. Discussion and conclusions -Pohorski dvor site

In this experimental field, a large heterogeneity according to soil moisture and chemicalphysical properties was observed. This could mask the real effect of applied fertilisers and liming on soil properties.

Our goal in the experiment was: 1) enrich soil with organic matter as a source of plant nutrients (especially with nitrogen), 2) increase pH for improving conditions for microbial activity (especially nitrification) and 3) speed up the mineralisation processes for releasing plant nutrients (especially nitrogen). The best solution to improve soil microbial activity and to avoid exhaustion of Corg (BM and LOM) in long term is to use liming with Compo guano, even if at the beginning the results were not encouraging.

The first time ( 2004), combinations of liming and Compo guano did not show any differences in BM and LOM, while liming without Compo guano slightly increased C mineralisation. The second time (2005), liming first increased microbial biomass and decreased LOM (in May). Later (in September), the consequence was also a decrease of BM and LOM due to liming. However, in addition to providing substrate for the decomposers, organic amendments also can improve soil water retention [START_REF] Carter | Long-term influence of compost on available water capacity of a fine sandy loam in a potato rotation[END_REF][START_REF] Rawls | Effect of soil organic carbon on soil water retention[END_REF]. This was also partly found in our measurements of water potential, where additional organic matter from the grass in inter-row contributed to higher available water content in upper soil layers. In our study we also found that liming also favoured drainage. Thus, amendments contribute to improved soil health through a lot of direct and indirect effects (Magdoff, 2001;[START_REF] Snapp | Evaluating cover crops for benefits, costs and performance within cropping system niches[END_REF].

The aim of this research was to develop an efficient and fast methodology combining physical, chemical, and microbiological soil parameters to evaluate soil quality as a function of organic matter addition and liming in agricultural soils. Results showed that microbiological parameters are sensitive indicators of changes and improvements in soil fertility in a very short period of time. These results confirm that this investigation should be accompanied by the simultaneous determination of basic physical and chemical soil characteristics such as pH, CEC, EC, and FC. These abiotic characteristics are complementary for a better understanding of the biological and biochemical properties and support the final evaluation of soil quality [START_REF] Mäder | Soil ecology-Impact of organic and conventional agriculture on soil biota and its significance for soil fertility[END_REF][START_REF] Filip | Soil quality assessment: an ecological attempt using microbiological and biochemical procedures[END_REF][START_REF] Kumar | Crop residues and management practices: effects on soil quality, soil nitrogen dynamics, crop yield, and nitrogen recovery[END_REF].

General conclusions

1. A large heterogeneity according to the soil moisture and chemico-physical properties was observed on the experimental field. 2. Liming increased soil pH (especially in upper soil layer), while Compo guano slightly decreased soil pH. 3. Soil pH was higher in the upper soil layer.

Chapter 5: Pathogenic microbes in soil

According to the fact that one of the goals of our study is also the assessment of soil health, some analyses of specific microbes were done in both locations. In Gačnik, irrigation water was the potential source of pathogens, while in Pohorski dvor it was organic fertilising.

I Gačnik site: effect of irrigation

The effect of irrigation water and slope on specific microbes was studied. Specific microbial analyses in Gačnik were done in July 2006 in the surface soil layer (0-5 cm) in two treated rows (IRR=irrigated and NIR=non-irrigated row) at three slope positions (upslope, midslope, downslope). This summer no irrigation was done due to enough water input from precipitation. In this situation, the short term effect of irrigation couldn"t be studied, but analyses were done with allowing a possibility that pathogens could remain in soils as a consequence of irrigation in previous seasons.

I.1 Summary of previous results

Before presenting the specific microbes at this location, some basic previous results should be remembered:

-Soil gravimetric water content increased from upslope to downslope and it was higher in non-irrigated row. -Soil pH didn"t vary according to slope and treatment. -Total carbonates were three times higher at upslope, comparing lower slope positions.

Irrigated row had higher total carbonates than non-irrigated row. -Total organic carbon and C/N ratio increased from upslope towards downslope and the values of both were higher in non-irrigated row. -Higher Corg and C/N in fraction A (>200 µm) were noticed in irrigated row.

-Soil mineral nitrogen (ammonium and nitrates) were higher at upslope and in irrigated row positions. -Soil bulk density at upslope was lower comparing lower slope positions and it was higher in non-irrigated row. -Structural stability was higher upslope and in non-irrigated row.

-Microbial soil biomass and microbial respiration increased towards downslope. Higher microbial biomass was found in irrigated row. -Irrigation water contained high amount of nitrates (on the borderline by Official Gazette of Republic Slovenia) and high concentration of chemical (COD) and biochemical oxygen (BOD) demands.

Parallel with the analyses of specific microbes, soil pH, temperature and gravimetric water content were measured in the surface soil layer at three slope positions. No significant difference was noticed between sampling locations regarding soil temperatures (5 cm depth) and soil pH. The average soil temperature (at the sampling date) was 25.5 • C and soil pH (in water) was 8.15.

Statistically significant differences were noticed in gravimetric water content, where values increased from upslope towards downslope (Fig. 5. [START_REF]Organic fertilisers and liming increase soil microbial biomass and its activity. 2. Organic matter and liming affect soil pH and mineralization process. 3. Organic fertilising and liming have different effect on soil microbes in different soil types (according to water conditions)[END_REF], what confirms previous results.

I.2 Specific microbes' characterization

I.2.1 Enumeration of Fungi

The number of soil fungi followed the pattern of gravimetric water content in the slope, increasing towards downslope. No significant differences occurred between irrigated and nonirrigated rows, but there was a slight trend to higher fungi numbers in NIR row (Fig. 5.2). Fungal population density decreased from irrigation pond towards the end of the irrigation system.

I.2.2 Enumeration of Bacteria

Aerobic bacteria

Aerobic bacteria abundance was the highest at mid and downslope positions, while soil from upslope contained significantly less aerobic bacteria (Fig. 5.3). No significant differences occurred between irrigated and non-irrigated rows, but there was a slight trend to higher aerobic bacteria numbers in NIR row. Water from irrigation pond contained significantly less aerobic bacteria than water from irrigation pipe.

Anaerobic bacteria

Numbers of anaerobic bacteria showed significant differences along the slope, the lowest value being found upslope and the highest value downslope (Fig. 5.4). No significant differences occurred between irrigated and non-irrigated rows, but there was a slight trend to higher anaerobic bacteria numbers in NIR row. Water from irrigation pond contained the highest number of anaerobic bacteria and this number decreased in water moving to irrigation pipes.

Total coliforms

Total coliforms significantly increased towards downslope, where IRR row showed higher number compared to NIR row (Fig. 5.5). The number of total coliforms in irrigation water increased while moving from water source to middle of irrigation system.

7,90E+07 8,30E+07 2,50E+08 1,70E+03 3,50E+03 5,00E+02 6,00E+07 1,40E+08 2,90E+08 1,00E+00 1,00E+01 1,00E+02 1,00E+03 1,00E+04 1,00E+05 1,00E+06 1,00E+07 1,00E+08 1,00E+09 IRR NIR log Aerobic bacteria (UFCg -1 ) 3,90E+05 1,60E+06 2,20E+06 8,00E+04 1,20E+05 3,00E+06 5,60E+05 1,80E+06 2,20E+06 1,00E+00 1,00E+01 1,00E+02 1,00E+03 1,00E+04 1,00E+05 1,00E+06 1

Faecal coliforms and E.coli

Faecal coliforms and E. coli were obviously present in higher numbers at downslope position, similarly to data of total coliforms (Fig. 5.6 & 5.7). Enumeration of faecal coliforms and E. coli gave higher numbers in IRR row again (at lower slope positions). Following the presence of these bacteria in irrigation water, irrigation pond was obviously the source of faecal coliforms.

,00E+05 1,20E+07 1,60E+07 7,30E+03 2,07E+03 2,40E+02 8,00E+05 1,20E+06 1,40E+06 1,00E+00 1,00E+01 1,00E+02 1,00E+03 1,00E+04 1,00E+05 1,00E+06 1,00E+07 1,00E+08 IRR NIR log Total coliforms (UFCg -1 ) 2,67E+02 5,00E+02 6,60E+03 1,40E+02 4,80E+02 1,90E+02 3,73E+02 3,67E+02 3,33E+02 1,00E+00 1,00E+01 1,00E+02 1,00E+03 1

I.2.3 Presence of viruses

Rota virus

All soils and water samples were free of Rotavirus (Fig. 5.8).

Hepatitis E virus (HEV)

HEV was present in all water samples (from irrigation pond and pipes) (Fig. 5.9a). In soil, HEV was detected only in IRR row at upslope position (Fig. 5. 9b).

IRR

I.3 Discussion

Agriculture is the cause and the victim of water pollution at the same time [START_REF] Ongley | Control of water pollution from agriculture[END_REF]. Most farmers use surface water rather than ground water for irrigation, due to availability and lower operational costs. The inherent difficulty is that surface water resources are generally more susceptible to microbial contamination. Irrigation with microbiologically poor-quality water is a potential contaminating way for fruits and vegetables by pathogens and once on foodstuffs such as vegetables, pathogens may persist under normal storage conditions over the usual time between purchase and consumption. Waterborne pathogens may survive for days to months in the environment (in soil or on crops), according to abiotic conditions (especially temperature and sunlight exposure) [START_REF] Gerba | Pathogens. -Encyclopedia of Hydrological Sciences[END_REF].

SOIL SAMPLES

A number of documented outbreaks of human infections were associated with the consumption of raw fruits, vegetables, and non-pasteurised fruit juices. The bacteria most commonly found in polluted water are coliforms excreted by humans [START_REF] Lawson | Waterborne outbreak of Norwalk virus gastroenteritis at a southwest US resort: role of geological formations in contamination of well water[END_REF][START_REF] Beller | Outbreak of viral gastroenteritis due to a contaminated well[END_REF][START_REF] De Serres | Molecular confirmation of hepatitis A virus from well water: epidemiology and public health[END_REF] and outbreaks with identified etiology were predominantly of bacterial origin, primarily with Escherichia coli O157:H7. Escherichia coli is an indicator organisms that is widely used to detect faecal contamination of water and the assumption is that if faecal coliform bacteria are present in a sample, then human pathogenic bacteria could also exist (FAO guideline, 1992). Infection has mainly been associated with consumption of lettuce, sprouts, and apple juice, but enterotoxigenic E. coli has also been linked to carrots [START_REF] Buck | Recent Trends in Microbiological Safety of Fruits and Vegetables[END_REF]. Furthermore, a special care must be taken to emerging Hepatitis E virus.

In our study, the distribution of bacteria and fungi was positively related to soil water content and soil organic matter (SOM). Fungi and bacteria were numerically more present at downslope position, where soil moisture, organic matter and microbial biomass were higher. At downslope, bulk density was higher as well, but soil moisture was a more important factor for aerobic bacteria and aeration there was probably good enough. Also anaerobic bacteria were mostly present at downslope, which was expected according to higher bulk density. Upslope position was very poor with soil fungi. Total and faecal coliforms were mostly present at downslope position.

According to treatment, no significant differences in fungi and bacteria enumeration occurred, while higher numbers of total and faecal coliforms were noticed in irrigated row. More coliforms in IRR row could therefore be as possible remains of previous irrigations. Indeed, most bacteria and viruses are known to die in a few weeks to a few months, but much longer survival times have also been reported (FAO guideline, 1992). The Slovenian government published a guideline for irrigation water: 1000 MPN/l total coliforms for the crops which are consumed raw or cooked (except for drip irrigation). In our water samples, the range of total coliforms was at the above-mentioned level (Slovenian guideline), what can be considered as risky. Mitigating circumstances is that drip irrigation is an exception and irrigation water does not have a direct contact with fruits.

Fungi and anaerobic bacteria decreased in irrigation water from the pond towards water pipes. The opposite was observed for the aerobic bacteria and coliforms, probably due to higher oxygen concentration in pipes. Water from irrigation pond contained significantly less aerobic bacteria than from irrigation pipe. Pipes were not always filled with water and most of the time oxygen availability was high enough to support microbial growth from dissolved organic carbon. Faecal coliforms and E. coli were detected in water samples as well with the highest number in irrigation pipe at downslope position.

HEV viruses were detected in water from irrigation system and in soil from upslope, which could represent a serious human health risk. Many studies [START_REF] Hamilton | Position of the Australian horticultural industry with respect to the use of reclaimed water[END_REF][START_REF] Toze | Reuse of effluent water-benefits and risks[END_REF] have shown that viruses are capable of entering the plant through the root system (manuring) or when irrigation aerosols contaminate the plant surface. There is a defined potential for food borne transmission of Hepatitis E virus (HEV) and rotavirus but corroborating information is lacking and this type of virus has not been isolated directly from foods.

In our study, high pollution in irrigation pipe was noticed, where also COD and BOD levels were higher than in the pond. Previous bacterial results support this ascertainment. Irrigation water was obviously the source of faecal coliforms and HEV virus. The question was what was the source of these pathogens in irrigation water. A possible explanation was faeces from the old field toilet, settled in the hill 50 m above the irrigation pond (15% slope). This toilet was not active anymore, but it could be used by seasonal workers occasionally. Additional source of pathogens could be the faeces of wild animals visiting the orchard.

II Pohorski dvor site: effect of organic fertiliser and lime

In Pohorski dvor, the effect of Compo guano (organic fertiliser) and liming on soil health was studied. The following treatments were included: no lime and no Compo guano [START_REF] Liming | without Compo guano) increased microbial biomass and decreased LOM as a short time effect. The long time effect was decreasing LOM and MB[END_REF], no lime with Compo guano (10), with Compo guano and no lime [START_REF]Organic fertilisers and liming increase soil microbial biomass and its activity. 2. Organic matter and liming affect soil pH and mineralization process. 3. Organic fertilising and liming have different effect on soil microbes in different soil types (according to water conditions)[END_REF] and with Compo guano and lime [START_REF]Compo guano (without liming) increased microbial mineralisation[END_REF]. For this purpose, enumeration of specific bacteria (coliforms, E.coli), viruses (Rotavirus, HEV) and fungi was done.

II.1 Summary of previous results

Before presenting the specific microbes at this location, some basic previous results should be remembered:

-Initial soil pH at this location was very low (4.83 in KCl). Combination of lime and Compo guano increased soil pH, while Compo guano alone increased soil acidity. -C/N ratio (10.9) indicates good microbial activity. The level of soil Corg is good (around 2 % in0-30 cm). -Liming alone had a positive short-time effect on microbial biomass (BM), but on the cost of lower labile organic matter (LOM) after intensive respiration. In long-term period, liming alone decreased both BM and LOM. Compo guano contributed to more intensive microbial respiration and slight increase of active Corg. Combination of Compo guano and liming increased soil microbial biomass. -Combination of lime and Compo guano contributes to higher soil nitrates values.

-During the study, liming slightly decreased gravimetric water content.

Parallel with analyses of specific microbes, soil pH, temperature and gravimetric water content were measured in the surface soil layer (0-5 cm). No significant difference was noticed among treatments regarding soil temperatures (5 cm depth) and soil pH. The average soil temperature (at the sampling date) was 12.5 • C and soil pH (in KCl) was 4.83.

II.2 Specific microbes' characterization

Specific microbial analyses were done in October 2006 in the upper soil layer (0-5 cm).

II.2.1 Fungi enumeration

Compo guano with liming (Treatment 6) and pure control (treatment 5) showed significantly higher number of fungi compared to the other treatments (Fig. 5.10).

Anaerobic bacteria

According to treatment, there were no significant differences in anaerobic bacteria enumeration (Fig. 5.12).

Total coliforms

Liming without Compo guano significantly increased number of total coliforms (Fig. 5.13). Indeed, the enumeration medium is not really specific and a rather wide range of bacteria can grow in these conditions.

log Faecal coliforms (UFCg -1 )

II.2.3 Presence of viruses

Rota virus was present in all soil samples, while no Hepatitis E virus was detected.

II.3 Discussion

Fungi were numerically more abundant in two very different situations: in the soils with lower pH (treatment 5; pH=5.3) and in the soils with higher pH (treatment 6; pH=6.6). Total bacteria (aerobic and anaerobic) were mostly present in the soils with higher pH (both treatments with liming). In general, fungi seem to dominate in acid soils. This has more to do with the inability of bacteria to compete with fungi at lower soil pH than to the better adaptability of fungi at these lower pH values. Fungi with their hyphae can grow into favourable micro sites in the soil, whereas bacterial may not be able to do so (Bezdicek et al., 2002).

Compo guano in combination with liming increased the number of fungi and aerobic bacteria.

Liming alone contributed to a slightly higher number of total coliforms, probably due to higher pH. Compo guano alone significantly contributed to a higher number of faecal coliforms, especially E. Coli. Adding Compo guano alone is therefore more risky for pathogens (faecal coliforms) than in combination with liming. Beside that, this combination was the most useful from microbial activity aspect. Treatments did not affect the presence of viruses. Rota virus was present in all soil samples, therefore Compo guano was not its source.

III. Short conclusions for both locations

1. Drip irrigation with poor sanitary quality water can be a potential source of pathogens pollution. 2. It has to be underlined that pathogens may survive in the soil for longer periods of time, more than a year.

3. Organic amendments are a good solution for replacing mineral nitrogen fertilisers, but they can be risky according to some pathogens which can remain after incorrect or bad composting procedure.

4. Microbes are in close relations with physico-chemical soil characteristics, therefore a comprehensive approach to soil quality and health should be taken.

According to previous conclusions, some recommendations are proposed:

1. From sanitary aspects, irrigation water should be regularly monitored to avoid potential pathogens for human health 2. It is very important to emphasize that organic products, which are applied as amendments or fertilisers, should be properly prepared and checked for certain pathogens. The use of compost in soils requires that it achieves an adequate degree of maturity, which implies stable organic matter content and the absence of phytotoxic compounds and plant or animal pathogens [START_REF] Bernal | Maturity and stability parameters of composts prepared with a wide range of organic wastes[END_REF]. Especially dangerous are organic amendments which originate from animal faeces.

3. Both studies are good examples for being cautious by working in agriculture.

Producing yield in a correct manner can enable food safety.

General discussion and conclusions

General discussion and conclusions

In agricultural practices in Slovenia, the importance of soil condition is generally underestimated. Underestimation of soil properties and poor understanding of soil conditions can have many bad consequences, which results in quality or quantity of yield, in soil degradation or even environmental pollution.

Obligatory agricultural soil analyses which are performed in Slovene laboratories (ordered by farmers) are very basic (chemical only). Physical and even microbiological analyses are ordered exceptionally, for some scientific researches. The reason is also that Slovene soil science labs usually lack such equipment. Especially soil microbiology is a very young science in Slovenia and a lot should be done for its support and development. Especially in agriculture, there is an enormous lack of this knowledge in Slovenia.

In 2011, around 1.6% of all agriculture lands (7.275. ha) were irrigated in Slovenia. Slovenian National irrigation project was established in 1998, but we still do not have any serious studies how irrigation affects soil properties or even soil microbes. It is also necessary to stress that the conditions in Slovenia are extremely heterogeneous and it is therefore required to perform analyses on the basis of locally specific conditions for every single scheme, which makes studies more complicated. In north eastern Slovenia many orchards lay on hilly terrains, so also the technical measures on different slopes and the possibility of erosion should be take into consideration. It is very important to estimate the benefit of irrigation after an appropriate soil analysis and before building the irrigation system and also after to supervise the effects of irrigation on soil properties as long as irrigation is used. With improper irrigation a lot of damage to the environment could be done. Monitoring irrigation water quality in presence of pesticide, metals, salts or even pathogens, is more an exception than a rule.

In the last few years organic food became very popular in Slovenia and every year more farmers decide for organic production. Slovenia still has convenient natural conditions for organic farming, so small farmers see in this trend a good or even the only solution for surviving (mostly in combination with so called "eco-tourism"). In the year 2010 almost 3% of Slovene farmers are registrated as organic producers, which represents 30.696 ha of all agricultural lands. Some consumers doubt the food safety in organic production because soil with applied material (like some organic fertilizers in our case) can be a potential pathogen source. This new challenges about food safety and organic production are very interesting and require further studies because it can also help people to be acquainted with healthy nourishment. In this area not much research was done in Slovenia.

According to the importance of the mentioned agricultural practices, our study focused on their impact on soil quality and health. It was interesting, that investigation work was performed on the field study, which is useful to get valuable experiences in soil understanding according to all accompanging circumstances.

In the first part we were dealing with irrigation practice including slope and their effects on soil properties, especially on soil structure and soil microbes. The second part is dealing with the possibility of enhancing microbial biomass and nitrogen nutrition with different combinations of organic fertiliser and liming.

In the first part of the thesis, some aims were settled according to irrigation and slope effect.

To achieve the first aim of the project, which was "to define the effect of irrigation and slope on soil physics, chemistry and soil microbiology", several physico-chemical and microbiological analyses were done. The main conclusions associated with irrigation and slope effect are:

-According to hilly terrain and land levelling, we were dealing with two groups of soil: one at upslope and another one at mid and downslope. Considering soil characteristics, slope effect was more expressed than irrigation effect. -According to slope, water gravimetric content, organic matter, microbial biomass and respiration increased towards downslope; while total carbonates and structural stability increased towards upslope. -Among chemical properties of irrigation water, only the amount of nitrates was high, which probably contributed to higher mineral nitrogen values in IRR soils. -Lower gravimetric water content in irrigated row could be explained by modification in root distribution and developing due to drip irrigation. -Irrigation leads to increasing of soil microbial biomass and its activity (as a short-time effect) and decreasing of total soil organic matter amount (as a long-term effect). Lower C/N ratio of soil organic matter and higher respiration (Cmin) are more intensive in IRR row with lower remaining SOM in this treatment. -Irrigation affects soil structure in sense of degradation, what is associated with organic matter reduction.

To achieve the second aim of the project, which was "to determine the connections between microbial indicators and (especially) physical properties of soils, with the interpretation of the results in the case of irrigation", some comparisons among important parameters were done.

The main conclusions associated with connections are: -Gravimetric water content is not always a major factor which governs microbial biomass and activity According to treatment, microbial biomass was higher in IRR row despite lower soil moisture. Too much water can also have a negative effect on soil microbes. -Comparing microbial biomass and void ratio, both parameters decrease according to depth. -According to treatment, microbial biomass was not in positive correlation with SOM, but according to slope and depth positive correlations between them were found. This is explained by higher C/N ratio and higher microbial respiration rate in IRR row. -A major microbiological biomass and its activity (including mineralisation) occurred in IRR row and here TOC was lower. Microbes may attack sedimentary organic matter and this could additionally explain lower TOC value there. Organic matter, which is entrapped in geological substratum (marl) may be mineralised by irrigation process, which is very important according to the environmental point of view. -Microbial biomass and its activity were not in positive correlation with structural stability, as expected. According to treatment, higher carbonate content was probably more important factor for higher structural stability than organic matter pool.

To achieve the third aim of the project, which was "to propose microbial indicators which could be useful for assessing soil quality, health and sustainability in the case of irrigation", the following proposals are made: -Soil microbial biomass, microbial respiration rate and labile organic matter pool quickly respond to environmental conditions as to irrigation.

-Monitoring irrigation water of some pathogens like faecal coliforms (including E. coli), HEV and Rota viruses enable us safe fruit production.

To achieve the forth aim of the project, which was "to contribute to the knowledge of sideeffects of irrigation on soil ecology", some conclusions were made. The main conclusions associated with side effect of irrigation:

-Irrigation causes some indirect consequences in soils like modifying of root system growth, what contributing to higher water demand and thus drier soils. -Irrigation impacts soil structural stability, which can affect water movement through the soil profile, erosion processes with run-off water along the slope and crusting. -Organic matter, which is entrapped in geological substratum (marl), may be mineralised by irrigation process, which is very important according to environmental point of view.

To achieve the fifth aim of the project, which was "to enable a comprehensive approach, including soil physical and microbial properties ", some relationships among the important parameters are emphasized: -Soil organic matter was not always positively related to structural stability: there is positive correlation according to treatment and negative correlation according to slope and depth. -A high percentage of total carbonates in soil contributes to higher structural stability, what explaining higher structural stability with lower organic matter content. -Seasonal variations of structural stability can not be explained only with soil water content, however, rainfall and microbial biomass information are helpful. -According to relationships between microbial parameters and physico-chemical soil characteristics, some findings are presented in the second aim.

To achieve the sixth aim of the project, which was "to control irrigation water and soil for possible water or soil-borne pathogens, some chemical and biological analyses were made.

The main conclusions associated with irrigation water as a potential source of pathogens are:

-Irrigation water contains high nitrate concentration, increasing soil nitrates in IRR row. -High chemical (COD) and biochemical oxygen demand (BOD) in irrigated water indicates water pollution. -The presence of faecal coliforms and HEV virus in irrigated row indicates pollution from irrigated water, which was applied more than one year ago. This means that a virus can stay in soil for a longer period of time.

The following hypotheses were examined according to irrigation project:

1. Irrigation and slope affect soil microbial biomass and activity. This hypothesis is confirmed for irrigation and slope. 2. Irrigation and slope affect on soil physical parameters like bulk density, structural stability, organic matter grain size fraction, gravimetric water content and available water content. This hypothesis is confirmed for porosity, structural stability, composition of organic matter grain size fractions, gravimetric water content and available water content (the last is confirmed only according to treatment).

The relationships between soil physical properties and soil microbial parameters are controlled by water supply and slope.

This hypothesis is confirmed for irrigation and slope, but it has to be studied in a complex manner. 4. Microbial and physical soil indicators are appropriate for assessing soil quality in case of irrigation. This hypothesis is confirmed for microbial biomass, respiration rate, labile organic matter pool and for structural stability.

Irrigation water can represent a potential source of pathogens.

This hypothesis is confirmed for faecal coliforms (including E. Coli) and HEV.

In the second part of the thesis, some aims were settled according to organic fertilising and liming.

To achieve the first aim of the project, which was "to elucidate the effect of applied organic matter on nutrient cycling, soil chemistry and soil microbiology (microbial biomass and microbial activity), some chemical and microbiological analyses were done. The main conclusions are:

-Compo guano contributes to a small increase in active Corg -Compo guano in the combination with lime increases microbial biomass and activity.

-Compo guano contributed to the highest nitrate values when in combination with liming.

To achieve the second aim of the project, which was "to elucidate the effect of organic mater (used as fertilizer) and liming on soil pH, mineralization processes", some microbiological analyses were done. The main conclusions are:

-Compo guano alone decreases soil pH, while in the combination with lime soil pH rises. -Compo guano (alone) contributes to more intensive microbial mineralisation.

-Liming alone had a positive short-term effect on microbial biomass (MB), but on the cost of lower labile organic matter (LOM) after intensive respiration. During the longer period, liming alone decreased both MB and LOM. -Liming increased soil pH (especially in upper soil layer). -Liming alone decreased soil moisture and increased water potential probably due to effects on pore space, inducing better water drainage and better structure. -Liming (without Compo guano) increased microbial biomass and decreased LOM as a short time effect. The long time effect was decreasing LOM and MB. -The interaction of Compo guano and lime together was not clear, but in long term this is probably the best solution because it had positive consequences on both soil pH and available nitrogen, while preserving fair levels of MB and LOM.

To achieve the third aim of the project, which was "to propose microbial indicators which could be useful for assessing soil quality and soil health in orchards", some proposals were made:

-Microbial biomass, labile organic matter pool and microbial mineralization can be used as a quick response to environmental conditions.

To achieve the fourth aim of the project, which was "to compare behavior of microbes under organic fertilizing and liming in two different soil types according to water conditions", the following ascertainment was found:

-Difference in soil water regime, which occurred between blocks, doesn"t affect soil microbes. Soil humidity is not such a limited factor for soil microbes as organic matter.

To achieve the fifth aim of the project, which was "to control presence of some pathogens in soils, some biological analyses were done:

-Organic amendments are a good solution for replacing mineral nitrogen fertilisers, but they can be risky on account of some pathogens (faecal coliforms and Rota virus in our case), which can remain after incorrect or bad composting procedure.

The following hypotheses are examined:

1. Organic fertilisers and liming increase soil microbial biomass and its activity This hypothesis is confirmed by the combination of both.

Organic matter and liming affect soil pH and mineralization process.

This hypothesis is confirmed (see the second achieved aim).

Organic fertilising and liming have different effect on soil microbes in different soil types (according to water conditions).

This hypothesis is rejected (see the fourth achieved aim).

New perspectives:

1. By analysing some physical and microbiological properties in one realistic field experiment with irrigation system or organic farming, it is possible to show some new perspectives to the producers and more attention might be paid to some important soil facts which were overlooked before. For this purpose, more educational training about the consequences of agricultural practises in the environment should be organised.

2. For improving the benefits of irrigation systems or organic farming, we need a more comprehensive approach for estimating soil quality and health. This evaluation requires focusing not only on chemical (fertility) considerations, but also on the dynamic soil conditionsa combination of physical, biological and chemical characteristics, which are directly affected by recent and current land use decisions and practices. It might be useful to find some quality indexes, which include the most important parameters and adjust them to special agricultural practices or land use.

3. Emphasis has to be placed on the quality of materials, which are used in agricultural practices and have a direct contact with soil. It does not matter if we deal with irrigation water or with organic fertiliser; we have to be sure about certain chemical or microbiological parameters (pathogens) according to environmental pollution policy or human health safety. For this reason, monitoring of irrigation water and preliminary analyses of organic fertilisers are required, but initially basic soil parameters which are the main limiting factors for soil microbial activity (pH, SOM, humidity), should be improved especially in organic farming.

4. For better estimation of the soil, we need to improve equipment and enlarge scientific groups according to work in this field. It would be convenient to settle at least one big (with few blocks) experiment without disturbing factors (like a slope), where the effect of irrigation/organic farming can be studied for a longer period of time.

5. It would be interesting to further investigate structural stability according to the participation of organic carbon from the bedrock, using isotopic methods of δC13 to distinguish different types of SOM. Further research on micro and macro-aggregates level can be made according to the amount of total and specific SOM types (fresh and sedimentary SOM). These analyses should be improved with microbial analyses as well to examine our hypothesis on microbial mineralisation of the sedimentary SOM.

6. It would be also interesting to study structural stability in organic farming according to different organic fertilisers in relationship with soil microbes.

7. According to soil health, some relations among polluted water or infected organic fertiliser, soils and yield (fruits) will be welcome to understand and ascertain the transport of certain pathogens.

According to previous perspective, enormous and interesting work in the future is waiting for us.

Fig. 2 .

 2 Fig. 2.1a: Location of Slovenia in Europe ........................................................................ Fig. 2.1b: The position of the experimental fields in Slovenia .......................................... Fig. 2.2: Locations of experimental fields in Slovenia .................................................... Fig. 2.3:Geological map of exposed bedrock in the surrounding of Maribor; insert from Geological map of Maribor 1:100 000[START_REF] Buser | Basic geological map of SFRY[END_REF] ......................Fig. 2.4:Monthly distribution of precipitations and average temperature inMaribor (1961Maribor ( -1990) ) ................................................................................... Fig. 2.5: Monthly distribution of precipitations through the years 2004 and 2005 at Maribor meteorological station, compared to 30-year (1961-1990) average monthly precipitations ...................................................................................... Fig. 2.6: Monthly distribution of average air temperatures through the years 2004 and 2005 in Maribor experimental station, compared to 30-years (1961-1990) average monthly air temperatures ..................................................................... Fig. 2.7: Aerophoto picture of experimental orchard in Gačnik ...................................... Fig. 2.8: Sketch of the studied site .................................................................................. Fig. 2.9: A panorama view on experimental orchard in Gačnik ......................................Fig. 2.10: General picture of experimental orchard in Gačnik ........................................... Fig. 2.11: Studied site with irrigated and non-irrigated rows. ........................................... Fig. 2.12: Dynamics of irrigation in the period 1998 -2005 (in days of irrigation per month) ...................................................................... Fig. 2.13: Aerophoto of the experimental orchard in Pohorski dvor .................................. Fig. 2.14: A panoramic view of experimental orchard in Pohorski dvor ........................... Fig. 2.15: Experimental site in organic apple production .................................................. Fig. 2.16: Schema of the experimental field in Pohorski dvor ........................................... Fig. 2.17: Biochemical composition of different organic products .................................... Fig. 2.18: Photograph showing the groups of three tensiometers located in the irrigated row and in the inter-row in Gačnik apple orchard ..................... Fig. 2.19: Measuring the Archimedes force ...................................................................... Fig. 2.20: Picture of the machine for structural stability ................................................... Fig. 3.1: Scheme of the slope with location of the two soil profiles ................................ Fig. 3.2: Soil profile from IRR to NIR rows (upslope position) ...................................... Fig. 3.3: Soil profile from IRR to NIR rows (downslope position) .................................. Fig. 3.4: Shady and sunny side in the row ...................................................................... Fig. 3.5: Structural crust covered by algae ...................................................................... Fig. 3.6: Sketch of the upslope soil profile ..................................................................... Fig. 3.7: Upslope Soil profile from the in inter-row ........................................................ Fig. 3.8: Scheme of the soil profile at downslope position .............................................. Fig. 3.9a: Soil profiles from IRR and NIR soils at downslope position ............................. Fig. 3.9b: Soil profiles from IRR and NIR soils at downslope position ............................. Fig. 3.10: Between wheel and under wheel soil organization downslope .......................... Fig. 3.11: Water retention curves in Gačnik. October 2004 .............................................. Fig. 3.12a: Measurements of water potential (ψ) in IRR row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 .................................... Fig. 3.12b: Measurements of water potential (ψ) in NIR row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 .................................... Fig. 3.12c: Measurements of water potential (ψ) in inter-row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 ....................................

5 : 6 : 5 : 6 :

 5656 Fig. 2.1a: Location of Slovenia in Europe ........................................................................ Fig. 2.1b: The position of the experimental fields in Slovenia .......................................... Fig. 2.2: Locations of experimental fields in Slovenia .................................................... Fig. 2.3:Geological map of exposed bedrock in the surrounding of Maribor; insert from Geological map of Maribor 1:100 000[START_REF] Buser | Basic geological map of SFRY[END_REF] ......................Fig. 2.4:Monthly distribution of precipitations and average temperature inMaribor (1961Maribor ( -1990) ) ................................................................................... Fig. 2.5: Monthly distribution of precipitations through the years 2004 and 2005 at Maribor meteorological station, compared to 30-year (1961-1990) average monthly precipitations ...................................................................................... Fig. 2.6: Monthly distribution of average air temperatures through the years 2004 and 2005 in Maribor experimental station, compared to 30-years (1961-1990) average monthly air temperatures ..................................................................... Fig. 2.7: Aerophoto picture of experimental orchard in Gačnik ...................................... Fig. 2.8: Sketch of the studied site .................................................................................. Fig. 2.9: A panorama view on experimental orchard in Gačnik ......................................Fig. 2.10: General picture of experimental orchard in Gačnik ........................................... Fig. 2.11: Studied site with irrigated and non-irrigated rows. ........................................... Fig. 2.12: Dynamics of irrigation in the period 1998 -2005 (in days of irrigation per month) ...................................................................... Fig. 2.13: Aerophoto of the experimental orchard in Pohorski dvor .................................. Fig. 2.14: A panoramic view of experimental orchard in Pohorski dvor ........................... Fig. 2.15: Experimental site in organic apple production .................................................. Fig. 2.16: Schema of the experimental field in Pohorski dvor ........................................... Fig. 2.17: Biochemical composition of different organic products .................................... Fig. 2.18: Photograph showing the groups of three tensiometers located in the irrigated row and in the inter-row in Gačnik apple orchard ..................... Fig. 2.19: Measuring the Archimedes force ...................................................................... Fig. 2.20: Picture of the machine for structural stability ................................................... Fig. 3.1: Scheme of the slope with location of the two soil profiles ................................ Fig. 3.2: Soil profile from IRR to NIR rows (upslope position) ...................................... Fig. 3.3: Soil profile from IRR to NIR rows (downslope position) .................................. Fig. 3.4: Shady and sunny side in the row ...................................................................... Fig. 3.5: Structural crust covered by algae ...................................................................... Fig. 3.6: Sketch of the upslope soil profile ..................................................................... Fig. 3.7: Upslope Soil profile from the in inter-row ........................................................ Fig. 3.8: Scheme of the soil profile at downslope position .............................................. Fig. 3.9a: Soil profiles from IRR and NIR soils at downslope position ............................. Fig. 3.9b: Soil profiles from IRR and NIR soils at downslope position ............................. Fig. 3.10: Between wheel and under wheel soil organization downslope .......................... Fig. 3.11: Water retention curves in Gačnik. October 2004 .............................................. Fig. 3.12a: Measurements of water potential (ψ) in IRR row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 .................................... Fig. 3.12b: Measurements of water potential (ψ) in NIR row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 .................................... Fig. 3.12c: Measurements of water potential (ψ) in inter-row with distribution of rainfall (RR) at downslope position, in Gačnik 2004 ....................................

Fig. 3 . 1 : 4 : 5 : 4 : 5 : 6 :

 3145456 Fig. 3.13a: Measurements of water potential (ψ) in IRR row with distribution of rainfall (RR) in Gačnik, 2005 ....................................................................... 67 Fig. 3.13b: Measurements of water potential (ψ) in NIR row with distribution ....................... of rainfall (RR) in Gačnik, 2005 ....................................................................... 67 Fig. 3.13c: Measurements of water potential (ψ) in inter-row with distribution of rainfall (RR) in Gačnik, 2005 ....................................................................... 67 Fig. 3.14: Particle size distribution according to slope, treatment (IRR/NIR) and soil depth ................................................................................................... 71 Fig. 3.15: Distribution of SOM (values are multiplied by 3), C/N, CEC and CaCO 3 according to slope, treatment (IRR/NIR) and soil depth .................................... 73 Fig. 3.16a: Distribution of total CaCO 3 according to a depth, slope and treatment .............. 74 Fig. 3.16b: Distribution of active CaCO 3 according to a depth, slope and treatment ........... 74 Fig. 3.17a: Distribution of Corg according to a depth, slope and treatment ......................... 75 Fig. 3.17b: Distribution of C/N org according to a depth, slope and treatment. ................... 75 Fig. 3.18a: Distribution of NH 4 + according to depth, slope and treatment ........................... 76 Fig. 3.18b: Distribution of NO 3 -according to depth, slope and treatment ........................... 76 Fig. 3.19: Distribution of Corg in surface soil layer (0-5) cm along the slope ................... 80 Fig. 3.20: Distribution of total CaCO 3 and Corg according to slope and treatment in the surface soil layer from September 2005 .................................................. 81 Fig. 3.21a: Void ratio versus water ratio relationships according to different situation (IRR row) and depth at downslope position ..................... 84 Fig. 3.21b: Void ratio versus water ratio relationships according to different situation (NIR row) and depth at downslope position ..................... 84 Fig. 3.21c: Void ratio versus water ratio relationships according to different situation (inter row) and depth at downslope position ..................... 85 Fig. 3.21d: Void ratio versus water ratio relationships according to different situation (under wheel) and depth at downslope position ................ 85 Fig. 3.22: Comparison of clods void ratio in soils from inter-row according to depth ....... 86 Fig. 3.23a: Void ratio versus water ratio relationships according to treatment (IRR), depth and slope position......................................................... 89 Fig. 3.23b: Void ratio versus water ratio relationships according to treatment (NIR), depth and slope position ........................................................ 89 Fig. 3.24a: Distribution of sedimentary organic carbon (OC) stocks in fraction C according to slope, treatment and depth in Gačnik, October 2004 ..................... 98 Fig. 3.24b: Distribution of fresh organic carbon (OC) stocks in fraction C ............................. according to slope, treatment and depth in Gačnik, October 2004 ..................... 98 Fig. 3.25: Sedimentary and fresh organic carbon stocks (0 -30 cm) according to grain size fractions, slope positions and treatments ........................................... 99 Fig. 3.26a: Comparison of Corg with C/N in Gačnik, October 2004 ................................. 101 Fig. 3.26b: Comparison of Corg with 13 δC in Gačnik, October 2004 ................................ 101 Fig. 3.26c: Comparison of C/N with 13 δC in Gačnik, October 2004 ................................. 101 Fig. 3.27: Mean value of gravimetric water content (%) at downslope position according to depth and traitment, May 2004 ................................................... 104 Fig. 3.28: Distribution of gravimetric water gradient (W) from midslope to downslope in Gačnik, September 2004 ........................................................... 104 Fig. 3.29a: Distribution along the slope of gravimetric water content (W) in the upper soil layer, Gačnik, May 2005 .......................................................... 105 Fig. 3.29b: Distribution along the slope of gravimetric water content (W) in the deeper soil layer (b), Gačnik, May 2005 ................................................... 105 Fig. 3.30: Distribution of gravimetric water content (W) from upslope

4 : 5 : 6 : 1 : 4 :

 45614 Particle size distribution of the three layers at downslope position .................... 63 Tab. 3.Monthly summer rainfall in mm, Maribor (from Fig. 2.5) ................................ 64 Tab. 3.Main characteristics of irrigation water, October 2007 ..................................... 69 Tab. 3.7a: Basic soil characteristics of irrigated and non irrigated rows at upslope position, September 2005 .................................................................... 72 Tab. 3.7b: Basic soil characteristics of irrigated and non irrigated rows at midslope position, September 2005 ................................................................................. 72 Tab. 3.7c: Basic soil characteristics of irrigated and non irrigated rows at downslope position, September 2005 ................................................................................. 72 Tab. 3.8: Chemical analyses of mineral nitrogen forms in Gačnik, July 2007 .................. 75 Tab. 3.9: Distribution of Corg, total CaCO 3 and active lime through soil profiles at upslope and downslope positions in Gačnik, July 2006 .................................... 78 Tab. 3.10: Distribution of Corg along the slope. July 2006 ................................................ 79 Tab. 3.11: Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in IRR and in NIR rows, inter-row and under wheel at downslope position May ..................................... 83 Tab. 3.12: Clods void ratio (e c ) and inter-clods void ratio in Gačnik, May 2004 ................ 86 Tab. 3.13a: Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in IRR row according to depth at three slope positions, May 2006 .......................................................... 87 Tab. 3.13b: Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in NIR row according to depth at three slope positions, May 2006 .......................................................... 88 Tab. 3.14: Comparison different situations at 20-25 cm (data from Tab. 3.11) .................. 91 Tab. 3.15: A, B and C fraction size (%) according to depth and slope position, in irrigated and in non-irrigated rows ............................................................... 92 Tab. 3.16: CaCO 3 content (g.100 g -1 ) in the whole sample and in grain size fractions A, B & C according to depth and slope position, in irrigated Index XII and non-irrigated rows ..................................................................................... Tab. 3.17: Organic carbon content (g.100 g -1 ) in the whole sample and in grain size fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows ..................................................................................... Tab. 3.18: C/N ratio of grain size fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows ..................................................... Tab. 3.19: 13 δC Isotopic composition of fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows ............................................ Tab. 3.20: Stocks of sedimentary and fresh organic carbon (OC) in T.ha -1 .cm -1 in fractions A, B & C according to depth and slope position, in irrigated (IRR) and non-irrigated (NIR) rows ............................................... Tab. 3.21: Sedimentary versus fresh Organic carbon (OC) stock ratios in 0-30 cm layer (T.ha -1 ) according to size fraction, depth, slope position and treatment ............. Tab. 3.22: Chemical analysis of organic carbon (Corg), nitrogen (Norg), C/N ratio and Cu (EDTA) at downslope position in Gačnik, May 2004 ................................ Tab. 3.23: Spec. respiration (day -1 ) and turnover time (day); Gačnik, May 2004 ............. Tab. 3.24: Spec. respiration (day -1 ) and turnover time (day), Gačnik, September 2004 .... Tab. 3.25: Water stable aggregates (WSA) and gravimetric water content at sampling time (W) in October 2004 ............................................................ Tab. 3.26: Water stable aggregates (WSA) and gravimetric water content (W) at sampling time, May 2005 ........................................................................... Tab. 4.Comparison of soil morphological properties between block I and block III, Pohorski dvor 2005 ........................................................................................ Tab. 4.2: Physico-chemical soil analyses at Pohorski dvor in the studied blocks, May 2004 ....................................................................................................... Tab. 4.3: Physico-chemical soil analyses at Pohorski dvor according to treatments, May 2004 ....................................................................................................... Tab. 4.Volumetric water content (θ) at different pressure points in blocks I and III (treatment 5=pure control), at Pohorski dvor 2004.......................................... Tab. 4.5:

  Both experimental fields are located in northeastern Slovenia, 10 km from Maribor (Fig. 2.1a & b). The first location named Gačnik is settled in the north of Maribor and the second experimental area named Pohorski dvor is settled on the foothill of Pohorje, in south of Maribor (Fig. 2.2).

Fig. 2 .

 2 Fig. 2.1a & b: Location of Slovenia in Europe and position of the experimental fields in Slovenia.

Fig. 2 . 2 :

 22 Fig. 2.2: Locations of experimental fields in Slovenia.

Fig. 2 . 5 :

 25 Fig. 2.5: Monthly distribution of precipitations through the years 2004 and 2005 at Maribor meteorological station, compared to 30-year (1961-1990) average monthly precipitations.

Fig. 2 . 6 :

 26 Fig. 2.6: Monthly distribution of average air temperatures through the years 2004 and 2005 in Maribor experimental station, compared to 30-years (1961-1990) average monthly air temperatures.

7 :

 7 Fig. 2.7: Aerophoto picture of experimental orchard in Gačnik

Fig. 2 . 8 :

 28 Fig. 2.8: Sketch of the studied site

Former

  Fig. 2.9: A panorama view on experimental orchard in Gačnik

  Fig. 2.11: Studied site with irrigated and non-irrigated rows (picture was taken from the upslope position)

1 :

 1 Fig. 2.12: Dynamics of irrigation in the period 1998 -2005 (in days of irrigation per month).

Fig. 2 .

 2 Fig. 2.13: Aerophoto of the experimental orchard in Pohorski dvor

  Fig. 2.15: Experimental site in organic apple production (picture was taken from downslope position)

  characterisations: -Chemical oxygen demand (COD) -Biochemical oxygen demand (BOD) 4. Organic matter fractionation (in three size fractions: 200-2000 µm, 50-200 µm, 0matter pool ( LOM) -Enumeration of aerobic/anaerobic bacteria (No• aer./anaer. bacteria) -Enumeration of fungi (N• fungi) -Enumeration of coliform bacteria (N•coliforms) -Presence of HEV and Rota viruses (HEV, Rota) II.1.

Fig. 2 .

 2 Fig. 2.18: Photograph showing the groups of three tensiometers located in the irrigated row and in the inter-row in Gačnik apple orchard.

Fig

  Fig. 2.19: Measuring the Archimedes force

T

  Fig. 2.20: Picture of the machine for structural stability

Fig. 3 . 1 :

 31 Fig. 3.1: Scheme of the slope with location of the two soil profiles

Fig. 3 . 2 :

 32 Fig. 3.2: Soil profile from IRR to NIR rows (upslope position)

  [START_REF] Liming | without Compo guano) increased microbial biomass and decreased LOM as a short time effect. The long time effect was decreasing LOM and MB[END_REF].

Fig. 3 . 4 : 1

 341 Fig. 3.4: Shady and sunny side in the row Fig. 3.5: Structural crust covered by algae

Fig. 3 . 6 : 7 :

 367 Fig. 3.6: Sketch of the upslope soil profile

Fig

  Fig. 3.8: Scheme of the soil profile at downslope position

Fig. 3 .

 3 Fig. 3.10: Between wheel and under wheel soil organization downslope (the size of knife is 30 cm).

Fig. 3 .

 3 Fig. 3.11: Water retention curves in Gačnik. October 2004.

  , at downslope position. Distributions of soil water potential according to treatment and season with rainfall distribution by weeks are presented in Fig. 3.12a, b & c and 3.13a, b & c. Measurements of water potential are presented in Annex 5.

Fig. 3 .Fig. 3 .

 33 Fig. 3.12a & b & c: Measurements of water potential (ψ) in IRR row (a), in NIR row (b) and inter-row (c) with distribution of rainfall (RR) at downslope position, in Gačnik 2004.

Fig. 3 . 14 :

 314 Fig. 3.14: Particle size distribution according to slope, treatment (IRR/NIR) and soil depth.

  Fig. 3.15: Distribution of SOM (values are multiplied by 3), C/N, CEC and CaCO 3 according to slope, treatment (IRR/NIR) and soil depth.

  Fig. 3.16a & b: Distribution of total and active CaCO 3 according to a depth, slope and treatment.

Fig. 3 .

 3 Fig. 3.17a & b: Distribution of Corg and C/N according to a depth, slope and treatment.

  Analyses of mineral nitrogen forms in soils were done in July 2007. The results are presented in Tab. 3.8 and Fig. 3.18a & b. Tab. 3.8: Chemical analyses of mineral nitrogen forms in Gačnik, July 2007 (Faculty of Agriculture and Life Sciences, Department of Chemistry, Agrochemistry and Soil Science).

Fig. 3 .

 3 Fig. 3.18a & b: Distribution of NH 4 + and NO 3 -according to depth, slope and treatment.

  was observed in the Corg distribution along the slope. Maximum values were found in the inter-row: 2 ± 0.1%. Minimum values occurred at upslope position in IRR and NIR rows (0.76 and 0.8 % respectively) Almost the same pattern in Corg distribution was noticed along the slope in both treatments (IRR, NIR) and in inter-row: Corg increased towards downslope. Corg values in IRR and NIR rows were very similar, while Corg content was significantly higher in the inter-row. Tab. 3.10: Distribution of Corg along the slope (Faculty of Agriculture and Life Sciences, Department of Chemistry, Agrochemistry and Soil Science). July 2006

Fig. 3 . 19 :

 319 Fig. 3.19: Distribution of Corg in surface soil layer (0-5) cm along the slope.

  with the same analytical method, indicating strong soil heterogeneity, especially at upper positions of slope.Soil surface evolution of organic carbon and CaCO 3 contents (Tab. III.3a,b,c) according to slope showed two inverse patterns: Corg increased toward downslope while CaCO 3 decreased(Fig 3.20). Moreover, upslope surface content in Corg and CaCO 3 drew nearer marl composition taken from Tab. 3.9. The trends were similar according treatments.

Fig. 3 . 20 :

 320 Fig. 3.20: Distribution of total CaCO 3 and Corg according to slope and treatment in the surface soil layer from September 2005.

84**

  Mean water saturation ratio, calculated on two data only (without *).

Fig. 3 .

 3 Fig. 3.21a & b: Void ratio versus water ratio relationships according to different situation (IRR and NIR rows) and depth at downslope position (bisector line = water saturation line)

Fig. 3 . 22 :

 322 Fig. 3.22: Comparison of clods void ratio in soils from inter-row according to depth.

Fig. 3 .

 3 Fig. 3.23a & b: Void ratio versus water ratio relationships according to treatment (IRR. NIR), depth and slope position (bisecting line = water saturation line).

  Fig. 3.24a & b: Distribution of sedimentary (a) and fresh (b) organic carbon (OC) stocks in fraction C according to slope, treatment and depth in Gačnik, October 2004.

  Fig. 3.25: Sedimentary and fresh organic carbon stocks (0 -30 cm) according to grain size fractions (fraction A > 200 µm, fraction B: 200-50 µm, fraction C <50 µm), slope positions (UP = upslope, MID = midslope, DOWN = downslope) and treatments (NIR = non-irrigated, IRR = irrigated). (Table of OC stock in 0-30 cm soil layer is represented in Annex 3).

Fig. 3 .

 3 Fig. 3.26a, b &c: Comparison of Corg with C/N (a) and with 13 δC (b) and comparison of C/N and 13 δC (c) in Gačnik, October 2004.

Fig. 3 . 28 :

 328 Fig. 3.28: Distribution of gravimetric water gradient (W) from midslope to downslope in Gačnik, September 2004.

  Fig. 3.29a & b: Distribution along the slope of gravimetric water content (W) in the upper soil layer (a) and in deeper soil layer (b), Gačnik, May 2005.

Fig. 3 . 30 :

 330 Fig. 3.30: Distribution of gravimetric water content (W) from upslope to downslope in Gačnik, September 2005.

Fig. 3 . 31 :

 331 Fig. 3.31: Distribution of soil microbial biomass (BM) in Gačnik, May 2004.

Fig. 3 .

 3 Fig. 3.32: Distribution of labile organic matter pool (LOM) in Gačnik, May 2004.

Fig. 3 . 33 :

 333 Fig. 3.33: Distribution of Cmin in Gačnik, May 2004.

Fig. 3 . 34 :

 334 Fig. 3.34: Distribution of soil organic matter (SOM) components in total Corg, Gačnik, May 2004.

  Fig. 3.35: Distribution of microbial biomass (BM) in Gačnik, September 2004.

  Fig. 3.37: Distribution of Cmin in Gačnik, September 2004.

Fig. 3 .

 3 Fig. 3.38: Distribution of NO 3 -in Gačnik, September 2004. 0 50 100 150 200 250 300 350 400

  Fig. 3.40a & b: Distribution of microbial biomass (BM) in the upper soil layer (0-15 cm) (Fig. III.48a) and in the deeper soil layer (15-30 cm) (Fig. III.48b), Gačnik, May 2005.

Fig. 3 . 41 :

 341 Fig. 3.41: Distribution of labile organic matter pool (LOM) in the upper soil layer, Gačnik, May 2005.

Fig. 3 .

 3 Fig. 3.42a & b: Distribution of microbial biomass (BM) in the upper soil layer (Fig. III.50a) and in the deeper soil layer (Fig. III.50b), Gačnik, September 2005.

Fig. 3 . 43 :

 343 Fig. 3.43: Distribution of labile organic matter pool (LOM) in Gačnik, September 2005.

  3.44a & b, Fig. 3.45).

  Fig. 3.44: Water stable aggregates (WSA) in October 2004 after 2 hours (a) and after 6 hours (b).

Fig. 3 . 45 :

 345 Fig. 3.45: Comparison of water stable aggregates (WSA) after 2 and 6 hours in Gačnik, October 2004.

  Fig. 3.46a & b: Comparison of water stable aggregates (WSA) according to sun exposure and irrigation (IRR, NIR) after 2 hours in 0-5 cm layer (a) and in 5-15 cm layer (b) in Gačnik, May 2005.

  & b) it can be seen that there were no significant correlations between WSA and Corg or the percentage of clay.

Fig. 3 .

 3 Fig. 3.47a, b, c & d: Correlations between water stable aggregates (WSA) and Corg (a), clay content (b) and total carbonates (c) from 0-30 cm; distribution of WSA and carbonates according the slope in the surface soil layer (d), 2004.

Fig. 3 .

 3 Fig. 3.48a & b: Correlations between gravimetric water content (W) and structural stability (WSA) in October 2004 (a) and in May 2005 (b).

  Fig. 3.50a & b: Correlation between structural stability (WSA) and fresh OC (a) or sedimentary OC stock (T.ha -1 .cm -1 ).

  stock (T.ha -1 .cm-1 )

Fig. 4 . 1 :

 41 Fig. 4.1: Soil pH KCl at Pohorski dvor, May 2004.

4 . 1 )Fig. 4 . 2 :

 4142 Fig. 4.2: Soil pH KCl at Pohorski dvor, November 2004.

Fig. 4 . 3 :

 43 Fig. 4.3: Soil pH KCl at Pohorski dvor, May 2005.

Fig. 4 . 4 :

 44 Fig. 4.4: Soil pH KCl at Pohorski dvor, November 2005.

Fig. 4 . 5 :

 45 Fig. 4.5: Time distribution of soil pH KCl in upper soil layer (0-15 cm) at Pohorski dvor.

  -25 cm and 40-45 cm) values were lower and very similar. In block III, the mid-layer (40-45 cm) showed the highest values of volumetric water content, while the sub-surface layer (20-25 cm) showed the lowest values. Water retention curves in block I and III are presented in Fig. 4. 6a & b.

Fig. 4 .Fig. 4 .

 44 Fig. 4.6a: Water retention curve in block I, at Pohorski dvor 2004.

III. 1 . 2 Fig. 4 .Fig. 4 .

 1244 Fig. 4.7 a,b,c: Measurements of water potential in soils from treatment 5 (pure control) ( a), treatment 10 (liming only) ( b) and from inter-row (c), in block I with distribution of rainfall (RR) at Pohorski dvor 2004.

Fig. 4 . 9 :

 49 Fig. 4.9: Distribution of gravimetric water content (W) by treatments in blocks at Pohorski dvor, May 2004.

Fig. 4 . 10 :

 410 Fig. 4.10: Gravimetric water content (W) at Pohorski dvor, May 2004.

Fig. 4 .

 4 Fig. 4.11: Gravimetric water content (W) at Pohorski dvor, October 2004.

Fig. 4 . 12 :

 412 Fig. 4.12: Gravimetric water content (W) at Pohorski dvor, May 2005.

Fig. IV. 13 :

 13 Fig. IV.13: Gravimetric water content (W) at Pohorski dvor, October 2005.

Fig. 4 . 14 :

 414 Fig. 4.14: Microbial biomass (BM) at Pohorski dvor, May 2004.

Fig. 4 .

 4 Fig. 4.15: Labile organic matter pool (LOM) in upper soil layer at Pohorski dvor, May 2004.

Fig. 4 . 16 :

 416 Fig. 4.16: Cmin at Pohorski dvor, May 2004.

Fig. 4 . 17 :

 417 Fig. 4. 17: Distribution of soil organic matter (SOM) components in total Corg (0-15 cm), Pohorski dvor, May 2004.

Fig. 4 .

 4 Fig. 4.18: Microbial biomass (BM) at Pohorski dvor, September 2004.

Fig. 4 . 19 :

 419 Fig. 4.19: Labile organic matter pool (LOM) in upper soil layer at Pohorski dvor, September 2004.

Fig. 4 .

 4 Fig. 4.21: Microbial biomass (BM) at Pohorski dvor, May 2005.

Fig. 4 . 22 :

 422 Fig. 4.22: Labile organic matter pool (LOM) in upper soil layer at Pohorski dvor, May 2005.

Fig. 4 .

 4 Fig. 4.24: Microbial biomass (BM) at Pohorski dvor, September 2005.

Fig. 4 . 25 :

 425 Fig. 4.25: Labile organic matter pool (LOM) in upper soil layer at Pohorski dvor, September 2005.

Fig. 4 .

 4 Fig. 4.28: Time distribution of microbial biomass (0-15 cm) at Pohorski dvor.

Fig. 5 . 1 :

 51 Fig. 5.1: Gravimetric water content in Gačnik, July 2006 (IRR=irrigated, NIR=non-irrigated row).

Fig. 5 . 2 :

 52 Fig. 5.2: Fungal population density in soil (0-5 cm) in Gačnik, July 2006.

Fig. 5 . 3 :

 53 Fig. 5.3: Aerobic bacteria enumeration in soil (0-5 cm) in Gačnik, July 2006.

Fig. 5 . 4 :

 54 Fig. 5.4: Anaerobic bacteria enumeration in soil (0-5 cm) in Gačnik, July 2006.

Fig. 5 . 5 :

 55 Fig. 5.5: Total coliforms in soil (0-5 cm) in Gačnik, July 2006.

Fig. 5 . 6 :

 56 Fig. 5.6: Faecal coliforms enumeration in soil (0-5 cm) in Gačnik, July 2006.

5

 5

Fig. 5 . 7 :

 57 Fig. 5.7: E. coli enumeration in soil (0-5 cm) in Gačnik, July 2006.

Fig. 5 . 8 :

 58 Fig. 5.8: Dot blot results for Rotavirus in water and soil samples (0-5 cm) in Gačnik, July 2006.

Fig. 5 .

 5 Fig. 5.9a & b: Dot blot results for HEV in water (a) and soil samples (b) in Gačnik, July 2006.

Fig. 5 .

 5 Fig. 5.10: Fungi enumeration in soil (0-5 cm) at Pohorski dvor, October 2006.

Fig. 5 .

 5 Fig. 5.11: Aerobic bacteria in soil (0-5 cm) at Pohorski dvor, October 2006.

Fig. 5 . 12 :

 512 Fig. 5.12: Anaerobic bacteria enumeration in soil (0-5 cm) at Pohorski dvor, October 2006.

Fig. V. 13 :Fig. 5 .

 135 Fig. V.13: Total coliforms in soil (0-5 cm) at Pohorski dvor, October 2006.

Table Index Tab. 2.1:

 Index Number of irrigation days per month in the period 1998 -2005, in Gačnik ......................................................................................................... 28 Tab. 2.2: Overview of applied pesticides during 2004 ..................................................... 29 Tab. 2.3: Overview of applied pesticides during 2005 ..................................................... 30 Tab. 2.4: Basic soil analysis (0-30 cm) in apple orchard cv. "Topaz" in Pohorski dvor in the year 2002 ......................................................................... 33 Tab. 2.5: Initial situation of soil mineral nitrogen before starting the experiment (April, 2002) ............................................................................ 33 Tab. 2.6: Composition of the three different organic fertilizers ........................................ 34 Tab. 2.7: Overview of all applied pesticides in the year 2004 .......................................... 35 Tab. 2.8: Overview of all applied pesticides in the year 2005 .......................................... 36 Tab. 2.9: Schedule of soil sampling and analysis in Gačnik by soil parameters during 2004-2006 ........................................................................................................ 38 Tab. 2.10: Schedule of water sampling and analysis in Gačnik in 2007 ............................. 39 Tab. 2.11: Schedule of soil sampling and analysis in Pohorski dvor by soil parameters during 2004-2006 ...

.......................................................................................... 40 Tab. 3.1: Description of upslope soil profile (in the row)................................................. 56 Tab. 3.2: Description of the downslope soil profile (in the rows) ..................................... 59 Tab. 3.3: Volumetric water content (θ) and water ratio ( ) at different pressure heads ..... 62 Tab. 3.

is presented in Fig. 2.4. 1961- 1990 Jan. Feb. Mar. Apr. May June July Aug Sept. Oct. Nov. Dec. RR (mm)

  Monthly distribution of precipitations and average temperature in Maribor

		49	50	68	80	94	119	118	129	99	87	93	61
	T (•C)	-1.3	1.1	5.2	10	14.7	17.9	19.6	18.7	15.2	10.1	4.5	0.1
	Fig. 2.4:

average climate conditions. (mm) Jan. Feb. Mar. Apr. May June July Aug Sept. Oct.

												Nov.	Dec.
	2004	52.3	33	97.2	57.4	67.5 174.7 70.8	70.3	81.7	87.7	45.5	39.2
	2005	14.7	52.3	34.5	92.5	77	56.2 173.4 219.5 125.5 18.7	70.1	70.7
	1961-	49	50	68	80	94	119	118	129	99	87	93	61
	1990

C) Jan. Feb. Mar. Apr. May June July Aug Sept. Oct.

	When comparing the precipitations in 2004 and 2005, a large difference is observed: the
	summer time (July, August) in 2004 was extremely dry, while in 2005 extremely wet. June
	2004 is the wettest month in the whole year, with much higher value compared to the long-
	lasting (1961-1990) mean value. Conversely, 2005 was an exceptional year with a rainy
	summer (518.4 mm rainfall during July, August and September) with maximal precipitation
	in August, so no irrigation was needed in this season.
												Nov.	Dec.
	2004	-1.9	0.8	3.5	10.3	12.8	17.5	19	19.3	14.1	11.4	4.3	0.2
	2005	-1.0	-3.2	3.4	10.0	15.2	18.4	19.7	17.1	15.2	9.9	3.4	-0.4
	1961-	-1.3	1.1	5.2	10.0	14.7	17.9	19.6	18.7	15.2	10.1	4.5	0.1
	1991

(•

Date Name and active substance Type of pesticide Dose per hectare

	Application of pesticides was done about 15 times per year, according to rainfall: in dry years
	11-12 times per season and in wet years 16-17 times per season (Tab. 2.2 & 2.3).
	The number of pesticides applications was fourteen in 2004 and sixteen in 2005.
	Herbicides which were used in strips (active chemical substances) were: oxyfluorfen,
	glyphosate and gluphosinate. Pesticides were used for preventing the invasion of insects
	(Oleodiazinon, Phosalone etc.) and fungi (Dithianon, Dichlofluanid etc.).
		Tab. 2.2: Overview of applied pesticides during 2004.
	9 th April	Oleodiazinon (oil + diazinon)	insecticide	10.0 l (800 l water)
		White oil (paraffinic oil)	insecticide	10.0 l (800 l water)
		Champion (cupper hydroxide 50%)	fungicide	2.5 kg (800 l water)
	19 th April	Chorus (ciprodinil 75%)	fungicide	0.25 kg (200 l water)
		Champion (cupper hydroxide 50%)	fungicide	0.75 kg (200 l water)
	26 th April	Chorus (ciprodinil 75%)		0.3 kg (200 l water)
	3 rd May	Delan (ditianon 70%)	fungicide	0.7 l (200 l water)
		Karathane (dinokap 35%)	fungicide	0.6 l (200 l water)
	7 th May	Delan (ditianon 70%)	Fungicide	0.7 l (200 l water)
	14 th May	Zato (trifloksistrobin 50%)	fungicide	0.15 kg (200 l water)
		Polyram comby (metiram)	fungicide	2.5 kg (200 l water)
	24 th May	Captan (kaptan)	fungicide	2,0 kg (200 l water)
		Score (difenokonazol 25%)	fungicide	0.25 l (200 l water)
	31 th May	Captan (kaptan)	Fungicide	2.5 kg (200 l water)

Date Name and active substance Type of pesticide Dose per hectare 7 th

		Tab. 2.3: Overview of applied pesticides during 2005.
	June	Polyram comby (metiram)	fungicide	2.5 kg (200 l water)
		Indar 5 WG (fenbukonazol 5%)	fungicide	0.9 kg (200 l water)
		Basudin 600 EW (diazinon)	insecticide	1.2 l (200 l water)
	17 th June	Dithane M45 (mankozeb 80%)	Fungicide	2.5 kg (200 l water)
	28 th June	Delan (ditianon 70%)	Fungicide	0.7 l (200 l water)
		Karathane (dinokap 35%)	Fungicide	0.6 l (200 l water)
	12 th July	Captan (kaptan)	Fungicide	2.0 kg (200 l water)
	23 rd July	Dithane M45 (mankozeb 80%)	Fungicide	2.0 kg (200 l water)
		Zato (trifloksistrobin 50%)	fungicide	0.15 kg (200 l water)
		Pepelin (sulphur 80%)	fungicide	2.5 kg (200 l water)
		Zolone liquid (fosalon)	insecticide	2.5 l (200 l water)
	6 th August	Euparen (diklofluanid)	Fungicide	2.0 kg (200 l water)
		Basudin 600 EW (diazinon)	Insecticide	1.2 l (200 l water)

Date Name and active substance Type of pesticide Dose per hectar 15

	th April	Frutapon (parrafinic oil 98%)	Insecticide	15.0 l (600 l water)
		Sylit (dodin)	fungicide	1.6 l (600 l water)
		Cupro 190 SC (cupper sulphate 19%)	fungicide	4.0 l (600 l water)
		Basudin 600 EW (diazinon)	insecticide	1.2 l (600 l water)
	22 nd April	Chorus (ciprodinil 75%)	Fungicide	0.3 kg (200 l water)
		Karathane (dinokap 35%)	Fungicide	0.6 l (200 l water)
	28 th April	Chorus (ciprodinil 75%)	Fungicide	0.3 kg (200 l water)
		Bayleton spec (triadimefon)	fungicide	0.7 kg (200 l water)
	6 th May	Delan 750 SC (ditianon 70%)	Fungicide	0.6 l (200 l water)
		Score (difenokonazol 25%)	fungicide	0.2 l (200 l water)
		Calypso (tiakloprid 48%)	fungicide	0.2 l (200 l water)
	16 th May	Delan 750 SC (ditianon 70%)	Fungicide	0.7 l (200 l water)
	20 th May	Captan 50 WP (kaptan)	Fungicide	2.0 kg (200 l water)
		Stroby (krezoksim metal 50%)	Fungicide	0.2 kg (200 l water)
	30 th May	Delan 750 SC (ditianon 70%)	Fungicide	0.8 l (200 l water)
		Tilt (propikonazol)	Fungicide	0.6 l (200 l water)
	7 th June	Merpan (kaptan 50%)	Fungicide	1.2 kg (200 l water)
		Rubigan (fenarimol)	fungicide	0.6 l (200 l water)
		Mospilan (acetamiprid 20%)	insecticide	0.4 kg (200 l water)
	14 th June	Merpan DWG 80 (kaptan 50%)	Fungicide	1.2 kg (200 l water)
		Indar 5 WG (fenbukonazol 5%)	Fungicide	0.9 kg (200 l water)
	23 rd June	Dithane DG (mankozeb 75%)	Fungicide	2.5 kg (200 l water)
	27 th June	Chorus (ciprodinil 75%)	Fungicide	0.3 kg (200 l water)
	2 nd July	Sylit (dodin)	Fungicide	1.0 l (200 l water)
		Score (difenokonazol 25%)	Fungicide	0.25 l (200 l water)
	7 th July	Chorus (ciprodinil 75%)	Fungicide	0.3 kg (200 l water)
	14 th July	Polyram combi (metiram)	Fungicide	2.5 kg (200 l water)
		Karathane (dinokap 35%)	Fungicide	0.6 l (200 l water)
	21 st July	Euparen multi WG 50 (diklofluanid)	Fungicide	2.0 kg (200 l water)
		Zolone liquid (fosalon)	Insecticide	2.0 l (200 l water)
	6 th August	Euparen multi (tolilfluanid)	Fungicide	2.0 kg (200 l water)

  Basic soil analysis (0-30 cm) in apple orchard cv. "Topaz" in Pohorski dvor in the year 2002.Because of low soil pH (4.8), availability of nutrients and microbial activity might be affected. The level of SOM is very good. Available phosphorus(Olsen method, 1982) is very low, but potassium is in good level.

	Soil depth	SOM	pH in KCl Phosphorus	Potassium	Magnesium	Boron	Total
	(cm)	(%)		(mg/100g)	(mg/100g)	(mg/100g)	(ppm)	nitrogen
								(%)
	0-30	5.13	4.8	2.4	9.7	8.8	0.11	0.22
	Soil depth		NH 4 -N	NO 3 -N	w		Gravel
	(cm)		(mg/kg)	(mg/kg)	(%)		(%)
	0 -30		2.05		0.74	11.1		10.1
	30 -60		0.80		1.63	14.4		12.3
	60 -90		0.45		0.68	14.6		12.0

Tab. 2.4:

Tab. 2.5: Initial situation of soil mineral nitrogen before starting the experiment

(April, 2002)

.

  Overview of all applied pesticides in the year 2005.

	Tab. 2.8: Date Name and active substance	Type of	Dose per hectare
			pesticide
	10 th April	Lime-sulphur broth (calcium polysulphide; 60% sulphur)	Fungicide	35.0 L
	22 nd April	Cuprablau z-ultra (30 % copper in copper hydroxide form+	Fungicide	15.0 L
		2% zinc)
	3 rd May	Neem Azal (azadirahtin 1%)	Insecticide	3.0 L
		Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
	14 th May	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
	31 st May	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
		Cuprablau (30 % copper in copper hydroxide form+ 2% zinc)	Fungicide	1.5 kg (200 l water)
		Madex (1% granular virus Cydia pomonella)	Insecticide	0.15 l
	20 th June	Cosan	Fungicide	2.5 kg (200 l water)
		Cuprablau (30 % copper in copper hydroxide form+ 2% zinc)	Fungicide	0.8 kg (200 l water)
		Madex (1% granular virus Cydia pomonella)	Insecticide	0.1 L
	14 th July	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
		Madex (1% granular virus Cydia pomonella)	Insecticide	0.1 L
	2 nd August	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
		Cuprablau (30 % copper in copper hydroxide form+ 2% zinc)	Fungicide	0.8 kg (200 l water)
		Madex (1% granular virus Cydia pomonella)	Insecticide	0.1 L
	Date	Name and active substance	Type of	Dose per hectare
			pesticide
	9 th April	Lime-sulphur broth (calcium polysulphide; 60% sulphur)	fungicide	30.0 L
	21 st April	Lime-sulphur broth (calcium polysulphide; 60% sulphur)	Fungicide	12.0 L
		Neem Azal (azadirahtin 1%)	Insecticide	3.0 L
		Cuprablau (30 % copper in copper hydroxide form+ 2% zinc)	Fungicide	1.0 kg (200 l water)
	7 th May	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
		Cuprablau (30 % copper in copper hydroxide form+ 2% zinc)	Fungicide	1.0 kg (200 l water)
	18 th May	Cosan (80% sulphur)	Fungicide	2.5 kg (200 l water)
		Cupropin (50% copper hydroxide)	Fungicide	0.5 kg (200 l water)
	29 th May	Madex (1% granular virus Cydia pomonella)	Insecticide	0.15 L
	11 th June	Cosan (80% sulphur)	Fungicide	1.5 kg (200 l water)
	13 th July	Cocana soap (cocos fat)	Fungicide	20.0 kg (200 l water)
		Cosan (80% sulphur)	Fungicide	2.0 kg (200 l water)
	25 th July	Cocana soap (cocos fat)	Fungicide	20.0 kg (200 l water)

  Schedule of soil sampling and analysis in Pohorski dvor by soil parameters during2004-2006.

	Tab. 2.11: Organic fertiliser x lime
		no Compo-guano,	Compo-guano,	no Compo-guano,	Compo-guano,
		no lime	no lime	lime	Lime
	Physical analysis:
	Particle size distribution	May 04	May 04	May 04	May 04
	Chemical analysis:
	pH in H2O, KCl
	Total CaCO3
	Active CaCO3
	Corg
	Norg
	P2O5
	CEC
	Exch. Ca 2+
	Exch. Mg 2+
	Exch. K +
	Exch. Na
			Irrigation water source
		Pond	Pipe-bottom	Pipe-middle	Pipe-top
	Chemical analysis:
	pH in H2O	Oct.07	-	-	-
	Ca 2+	Oct.07
	Mg 2+	Oct.07
	K +	Oct.07
	Na +	Oct.07
	Cl -	Oct.07
	SO4 -	Oct.07
	HCO3 -	Oct.07
	SAR	Oct.07
	NH4 +	Oct.07
	NO2 -	Oct.07
	NO3 -	Oct.07
	EC	Oct.07
	Biochemical analysis:
	COD	Oct.07	-	-	-
	BOD	Oct.07
	Microbiological
	characterisations:
	N• aer./anaer. bacteria
	N• fungi
	N• coliforms
	HEV, Rota

+

More details about sampling in this location are explained in Annex 4.

  Statistical procedures were carried out with the software package Statgraphics Centurion XV (Statgraphic ® , 2005). The means were separated by the Duncan test, considering a significance level p<0.05. Analysis of variance (ANOVA) was used to find significance of effects of different factors on soil quality attributes.

Table 3 . 1 :

 31 Description of upslope soil profile (in the row)

	UPSLOPE

Table 3 . 2 :

 32 Description of the downslope soil profile (in the rows)

	DOWNSLOPE

  Main characteristics of irrigation water, October 2007 (Faculty of Agriculture and Life Sciences -Department of Microbiology, Biochemistry, Molecular Biology and Biotehnology and Faculty for Chemistry and Chemical Engineering).

	Parameter	Unit	IRR water (pond)	(IRR pipe)
	pH				7.8	8.0
	Ca ++	Mmol.L -1	4.38
	Mg ++	2.64
	K +				0.06
	Na +				0.72
	Cl -				0.56
	SO 4	-	0.35
	HCO 3	-	5.9
	SAR	0.38
	NH 4	+	mg.L -1	<0.1
	NO 2	-	0.045
	NO 3	-	10
	EC				mS.cm -1	0.61
	COD	Mg O 2 .L -1	180	240
	BOD	100	120

. 3.6:

  Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in IRR and in NIR rows, inter-row and under wheel at downslope position May 2004.

	Tab. 3.11: Treatment Depth cm	Bulk density g.cm -3	Porosity cm 3 .cm -3	Vol. water content cm 3 .cm -3	Grav. water content g.g -1	Void ratio	Water ratio	Water satur. ratio	Mean water satur. Ratio
			0.92	0.65	0.28	0.30	1.88	0.80	0.42
		3-7	1.03	0.61	0.29	0.28	1.57	0.75	0.48
			1.09	0.59	0.31	0.29	1.43	0.76	0.53	0.48
			1.27	0.52	0.40	0.31	1.09	0.83	0.76
	IRR	20 -25	1.2 1.39	0.55 0.48	0.37 0.41	0.31 0.29	1.21 0.91	0.81 0.78	0.67 0.86	0.76
			1.41	0.47	0.45	0.32	0.88	0.84	0.96
		40 -45	1.27	0.52	0.41	0.32	1.09	0.85	0.78
			1.28	0.52	0.40	0.32	1.07	0.84	0.78	0.84
			1.16	0.56	0.37	0.32	1.28	0.84	0.66
		3-7	1.32	0.50	0.40	0.31	1.01	0.81	0.80
			1.27	0.52	0.37	0.29	1.09	0.77	0.71	0.72
			1.4	0.47	0.42	0.30	0.89	0.80	0.90
	NIR	20 -25	1.29 1.25	0.51 0.53	0.42 0.39	0.33 0.31	1.05 1.12	0.86 0.82	0.82 0.73	0.82
			1.43	0.46	0.48	0.33	0.85	0.89	1.04*
		40 -45	1.3	0.51	0.43	0.33	1.04	0.88	0.85	0.95
			1.47	0.45	0.43	0.29	0.80	0.78	0.97	(0.91)**
			1.17	0.56	0.41	0.35	1.26	0.93	0.73
		20 -25	1.51	0.43	0.42	0.28	0.75	0.73	0.97	0.94
			1.52	0.43	0.48	0.31	0.74	0.83	1.12*	(0.85)**
	Inter-row	40 -45	1.41 1.41	0.47 0.47	0.43 0.46	0.30 0.33	0.88 0.88	0.81 0.86	0.92 0.98	0.98
			1.44	0.46	0.47	0.33	0.84	0.87	1.03*	(0.95)**
			1.38	0.48	0.47	0.34	0.92	0.90	0.98
		80-85	1.43	0.46	0.27	0.19	0.85	0.50	0.58	0.83
			1.36	0.49	0.45	0.33	0.95	0.88	0.93	(0.95)**
	Under wheel	20 -25	1.4 1.57 1.44	0.47 0.41 0.46	0.43 0.46 0.43	0.31 0.29 0.30	0.89 0.69 0.84	0.81 0.78 0.80	0.91 1.13* 0.95	1.0 (0.93)**

* Water saturation Ratio>1 => measurements errors either on bulk density or on gravimetric water content.

  Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in IRR row according to depth at three slope positions, May 2006. Bulk density, porosity, volumetric water content, gravimetric water content, void ratio, water ratio and water saturation ratio in NIR row according to depth at three slope positions, May 2006.

	Slope position Tab. 3.13b: . Depth cm Bulk density g.cm -3 Porosity cm 3 .cm -3 Volumetric water content cm 3 .cm -3 Gravimetric water content g.g -1 Void ratio Water ratio Water saturation ratio Mean water saturation ratio Slope position Depth cm Bulk density g.cm -3 Porosity cm 3 .cm -3 Volumetric water content cm 3 .cm -3 Gravimetric water content g.g -1 Void ratio Water Mean water Water saturation saturation ratio ratio ratio
		0 -5 0 -5	1.03 0.97 1.10 1.16	0.61 0.63 0.58 0.56	0.05 0.06 0.09 0.10	0.05 0.07 0.08 0.09	1.56 1.72 1.41 1.29	0.13 0.17 0.22 0.24	0.08 0.10 0.15 0.18	0.09 0.17
	Upslope Upslope	10 -15 10 -15	1.19 1.20 1.38 1.30	0.55 0.55 0.48 0.51	0.15 0.15 0.19 0.19	0.13 0.13 0.14 0.14	1.23 1.21 0.91 1.03	0.33 0.33 0.36 0.38	0.27 0.28 0.39 0.37	0.27 0.38
		20 -25 20 -25	1.45 1.27 1.19 1.22	0.45 0.52 0.55 0.54	0.21 0.18 0.18 0.18	0.14 0.15 0.15 0.14	0.83 1.09 1.22 1.16	0.38 0.39 0.39 0.38	0.46 0.35 0.32 0.33	0.41 0.32
		0 -5 0 -5	1.33 1.30 1.27 1.76	0.50 0.51 0.52 0.33	0.27 0.25 0.14 0.09	0.21 0.19 0.11 0.05	1.00 1.04 1.09 0.50	0.55 0.51 0.29 0.14	0.55 0.49 0.26 0.27	0.52 0.27
	Midslope Midslope	10 -15 10 -15	1.19 1.16 1.19 1.33	0.55 0.56 0.55 0.50	0.31 0.32 0.21 0.28	0.26 0.27 0.18 0.21	1.23 1.28 1.22 0.99	0.70 0.73 0.47 0.55	0.57 0.57 0.38 0.55	0.57 0.47
		20 -25 20 -25	1.37 1.15 1.43 1.21	0.48 0.57 0.46 0.54	0.36 0.35 0.28 0.26	0.26 0.30 0.19 0.22	0.94 1.30 0.86 1.18	0.69 0.80 0.52 0.58	0.74 0.61 0.60 0.49	0.67 0.54
		0 -5 0 -5	1.26 1.17 1.27 1.25	0.53 0.56 0.52 0.53	0.15 0.13 0.14 0.12	0.12 0.11 0.11 0.10	1.11 1.26 1.09 1.12	0.32 0.29 0.29 0.26	0.29 0.23 0.26 0.23	0.26 0.25
	Downslope Downslope	10 -15 10 -15	1.22 1.21 1.19 1.13	0.54 0.54 0.55 0.57	0.23 0.22 0.25 0.22	0.19 0.18 0.21 0.20	1.17 1.18 1.24 1.34	0.50 0.49 0.57 0.53	0.42 0.41 0.46 0.39	0.42 0.43
		20 -25 20 -25	1.30 1.33 1.38 1.33	0.51 0.50 0.48 0.50	0.30 0.22 0.29 0.28	0.23 0.17 0.21 0.21	1.05 0.99 0.92 0.99	0.62 0.44 0.56 0.55	0.59 0.45 0.62 0.56	0.52 0.59

5, 5-15 and 15-30 cm. Data from May 2006 are presented in Tab. 3.13a & b, and in Fig. 23a & b.

Tab. 3.13a:

  Comparison different situations at 20-25 cm (data fromTab. 3.11)

			water
		void ratio	saturation
			ratio
	IRR 20-25	1.07	0.76
	NIR 20-25	1.02	0.82
	inter-row 20-25	1.01	0.85
	under wheel 20-25	0.87	0.93

  C/N ratio of grain size fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows.

	Irrigated row (IRR) Tab. 3.18: Irrigated row (IRR)
	depth depth			Upslope Upslope			Midslope Midslope			Downslope Downslope
	(cm)		A		B		Corg C	A		B		Corg C	A		B		Corg C
	(cm) 0-5	A	13	B	11	C	total 4.4	A 22	B	13	C	total 6.8	A 19	B	13	C	total 6.9
	0-5 5-15	0.11 26	0.15	10	0.67	0.93 0.68 4.1 16	0.47	12	1.43	2.58 0.57 6.3 13	0.44	11	1.38	2.39 6.5
	15-30	(12)* 32	(16)	10	(72)	3.6	(26) 21	(18)	12	(55)	7.0	(24) 32	(18)	12	(58)	6.9
	5-15	0.10	0.11		1.54	1.75 0.03 Non-irrigated row (NIR) 0.23 1.06	1.32 0.14	0.28		1.16	1.58
	depth	(13)*	(15) Upslope (72)		(3)	(17) Midslope (80)		(9)	(18) Downslope (74)
	15-30 (cm)	0.12 A	0.09	B	0.46	0.67 0.10 C A	0.30	B	1.37	1.77 0.26 C A	0.27	B	1.27	1.80 C
	0-5	(18)* 15	(13)	9	(68)	4.1	(6) 15	(16)	15	(77)	6.5	(15) 12	(15)	12	(70)	6.7
	5-15		17		9		5.0	Non-irrigated row (NIR) 14 11	7.3	17		11		7.6
	depth 15-30		18	Upslope 5.0		Corg 3.5	13	Midslope 10		Corg 6.7	16	Downslope 11		Corg 7.3
		A		B		C	total	A	B		C	total	A	B		C	total
	0-5	0.16	0.16		0.64	0.96 0.20	0.28		1.22	1.70 0.22	0.38		1.29	1.89
	5-15	(17)* 0.16	(16) 0.19 V.1.5 Isotopic signature of organic carbon: δ 13 C (67) (12) (16) (72) 0.76 1.11 0.08 0.25 1.27 1.60 0.11 (12)	(20) 0.22		(68) 1.35	1.68
	)	(14)*	(17)		(68)		(5)	(15)		(80)		(6)	(13)		(80)
	15-30 0.08	0.09		0.44	0.61 0.08	0.20		1.07	1.35 0.15	0.24		1.27	1.66
		(13)*	(15)		(72)		(6)	(15)		(79)		(9)	(14)		(77)
																	while
	no evident differences occurred according to depth. Comparing IRR and NIR rows, the main
	difference occurred for fraction A, with higher mean C/N ratio in IRR than NIR row (21.5 and
	15 respectively).

* as percentage of total organic carbon in the sample V.1.4 C/N ratio C/N ratios by fraction were shown in Tab. 3.18 according to soil depth and slope position. C/N ratios varied from 3.5 to 32 in the different fractions. Fraction A showed the highest ratios compared to fractions B and C (13 to 32; 5 to 15 and 3.5 to 7, respectively). C/N ratio in fraction A increased from surface to deeper layers, especially in IRR treatment at upslope and downslope positions. C/N ratio in fraction B usually decreased with depth, while it was almost constant in fraction C. According to slope, IRR and NIR rows did not follow the same pattern in C/N. In IRR row, C/N ratio in fraction A was lower upslope compared to downhill positions. Inverse pattern occurred in the deeper soil layer

(5-15 cm)

. In NIR row, C/N ratio in fraction A did not show clear trend. In both rows, C/N ratio in fractions B and C generally increased towards downslope. C/N ratio was almost constant in B fraction according to slope and depth. C/N ratio in fraction C was the lowest upslope compared to lower positions,

. 3.19: 13

					Irrigated row (IRR)
	depth		Upslope			Midslope			Downslope
	(cm)	A	B	C	A	B	C	A	B	C
	0-5	-26.03	-26.08	-24.48	-28.11	-28.02	-27.22	-23.68	-26.87	-25.71
	5-15	-26.20	-25.04	-23.87	-27.09	-26.87	-25.35	-26.45	-26.32	-25.45
	15-30	-26.18	-26.76	-23.32	-27.03	-26.84	-25.78	-26.01	-26.58	-25.55
					Non-irrigated row (NIR)
	depth		Upslope			Midslope			Downslope
	(cm)	A	B	C	A	B	C	A	B	C
	0-5	-26.47	-26.04	-24.34	-27.69	-27.31	-25.65	-26.50	-26.73	-25.54
	5-15	-26.62	-26.22	-25.03	-27.25	-26.98	-25.74	-27.00	-26.64	-25.62
	15-30	-26.62	-24.30	-23.42	-27.26	-26.59	-25.39	-27.31	-26.97	-25.69

δC Isotopic composition of fractions A, B & C according to depth and slope position, in irrigated and non-irrigated rows

5 -15 cm 15 -30 cm

					irrigated
	Depth	OC Type	Grain size fractions Upslope	Total	Midslope Grain size fractions	Total	Downslope Grain size fractions	Total
				OC		OC		OC
	0 -5 cm			1,15		3,17		2,92
	5 -15 cm			0,93		1,62		1,93
	15 -30 cm			0,82		2,17		2,21
					non irrigated
	0 -5 cm			1,22		2,17		2,43
				1,43		2,03		2,15
				0,79		1,74		2,10

chemical soil characteristics II.1 General soil characteristics

  At the beginning of the experiment, some preliminary soil analyses were done. Samples were taken after the first treatment of fertilizing and liming.II.1.1 Comparison among blocsPhysico-chemical soil analyses in Pohorski dvor according to blocks is presented in Tab. 4.2. Texture grade was unique in all blocks (clay loam) till 30 cm of depth, but small differences occurred for clay, silt and loam within this texture grade. Soil from block I contained the lowest percentage of sand (17.5%) and the highest percentage of silt (52.3%). The opposite situation was recorded in block III: the highest percentage of sand (32.8%) and the lowest percentage of silt (40.3%) and clay (26.9%). Block II contained the highest clay content (32.8%). There were no differences in soil texture with depth. Corg, Norg and available phosphorus significantly decreased with depth. Exch. Mg, K and Cu were also higher in upper soil layer. No differences were detected in initial soil pH (in water and KCl) according to blocks. Soil pH was very low: the grand mean was 5.85 (in water) and4.83 (in KCl). Physico-chemical soil analyses at Pohorski dvor in the studied blocks, May 2004. Comparison between treatments Physico-chemical soil analyses in Pohorski dvor according to treatments is presented in Tab. 4.3. According to the texture, no strong differences among treatments were noticed till 30 cm of depth. Texture grade was always clay loam. No significant differences in Corg, Norg, C/N, pH (in water and KCl), CEC, Ca 2+ , Mg 2+ and Al 3+ were noticed among treatments. Compo guano contributed to higher available phosphorus (P 2 O 5 ), especially in upper soil layer. Compo guano increased exch. Na and K (in upper soil layer), while lime increased Mg. Values of exchangeable Mg and K were significantly higher in the upper soil layers. Manganese and copper did not show any differences Physico-chemical soil analyses at Pohorski dvor according to treatments, May 2004.

	II.1.2 Tab. 4.3: Treatment Pure control (no Compo guano, no lime) 5 Depth (cm) 0-15 15-30 % clay 31.2 30.6 % silt 46.6 44.0 % sand 22.2 24.2 Corg (gkg -1 ) 22.3 20.6 Norg (gkg -1 ) 2.04 1.91 C/N 10.9 10.8 NO3 -(mg N.kg -1 ) 1.16 1.31 P2O5 (gkg -1 ) 0.028 0.026 CEC (cmolkg -1 ) 12.13 11.95 Ca 2+ (cmolkg -1 ) 9.42 9.46 Na + (cmolkg -1 ) 0.051 0.046 II. Physico-Tab. 4.2: Block I Mg 2+ (cmolkg -1 ) 1.64 1.45 Depth (cm) 0-15 15-30 K + (cmolkg -1 ) 0.249 0.134 % clay 30.0 29.7 Al 3+ (cmolkg -1 ) 0.170 0.259 % silt 53.1 51.4 H + (cmolkg -1 ) 0.070 0.133 % sand 16.9 18.1 CuEDTA (mgkg -1 ) 7.01 5.67 Corg (gkg -1 ) 21.7 19.3 Mn 2+ (mgkg -1 ) 0.146 0.113	No Compo guano, lime 10 0-15 15-30 31.2 31.3 44.7 43.7 24.2 24.9 21.7 19.3 1.94 1.81 11.2 11.0 1.07 1.08 0.025 0.023 11.73 11.90 9.41 9.57 0.030 0.043 1.52 1.35 0-15 0.197 0.139 32.9 0.148 0.180 43.8 0.070 0.070 23.3 6.12 4.84 24.2 0.174 0.124	II	Compo guano, no lime 1 0-15 15-30 29.2 28.4 46.6 46.4 24.2 25.2 21.7 18.4 1.97 1.7 11.0 10.8 1.23 1.24 0.039 0.025 11.7 11.44 9.19 9.32 0.048 0.069 1.62 1.39 15-30 0.314 0.134 32.6 0.104 0.169 42.7 0.070 0.093 24.7 6.64 4.62 21.9 0.122 0.140	0-15 27.1 40.8 32.1 19.8	Compo guano, lime 6 0-15 15-30 28.5 28.3 45.8 44.2 25.7 27.5 21.9 19.4 2.02 1.80 10.9 10.8 1.62 1.50 0.040 0.027 11.50 11.42 8.88 9.16 0.057 0.608 1.52 1.25 III 0.261 0.130 15-30 0.143 0.166 26.7 0.080 0.060 39.7 6.29 4.94 33.6 17.6 0.131 0.219
	Norg (gkg -1 )	2.02		1.82		2.20			2.00		1.76	1.60
	C/N NO3 -(mg N.kg -1 ) 4.1: Comparison of soil morphological properties between block I and block III, 10.8 10.6 11.0 11.0 11.3 11.0 1.19 1.10 1.48 1.68 1.14 1.06 Pohorski dvor 2005. P2O5 (gkg -1 ) 0.027 0.018 0.033 0.027 0.039 0.032
	CEC (cmolkg -1 )	12.2	0-30 cm 12.2		13.5		30-60 cm 13.5		9.7	60-90 cm	9.4
	Ca 2+ (cmolkg -1 )	9.5	bl I	9.6	bl III	10.6	bl I		bl III 11.1		bl I 7.6	bl III 7.5
	Humidity Na + (cmolkg -1 )	dry to fresh 0.07	dry 0.06		fresh 0.04			Dry 0.06	wet 0.03	fresh 0.04
	Texture Mg 2+ (cmolkg -1 ) K + (cmolkg -1 ) Al 3+ (cmolkg -1 ) Structure H + (cmolkg -1 ) CuEDTA (mgkg -1 ) Mn 2+ (mgkg -1 )	loam 1.68 0.21 0.07 0-8 cm: fine crumble structure, then 0.07 6.04 0.12	loam 1.45 0.12 0.07 0-30 cm: fine crumble structure, then 0.07 4.18 0.17	30-40 1.71 0.25 loam, below 0.12 silt loam mixture subangular polyedric and cm: of 0.08 6.94 0.13	silt loam 1.53 0.15 0.14 Subangular 0.08 5.62 polyedric till 40 cm, then 0.14	silty loam 1.34 0.31 0.24 polyedric 0.08 6.58 0.18	1.11 silt loam 0.14 0.37 0.12 polyedric 5.25 0.14
		subangular	subangular	polyedric		polyedric
	polyedric and polyedric Corg and Norg were the highest in block II (23.03 and 2.10 g.kg -1 , respectively). The lowest polyedric and polyedric Consistence 0-10 cm: fragile, fragile, compact Fragile compact compact Corg and Norg were measured in block III (18.7 and 1.7 g.kg -1 respectively), which was not in crumbly accordance with previous observations of dark soil colour in this block. In general, soils from crumbly, after more compact Color 10 YR3/3 and 10 YR4/3 10 YR4/4 30-40 cm: 10 YR3/3, after 10 YR4/6 10 YR5/2 this experimental field contain good levels of soil organic matter (grand mean = 20.7 g.kg -1 10 YR5/8 Corg) and a C/N ratio (grand mean = 10.9) indicating a fair microbial activity. Nitrates
	10 YR5/8 and 10 YR5/2 from 50 cm For available phosphorus, significant differences were noticed among the blocks: block I had reached the highest values in block II. Hydromorphic features no no No from 60-80 cm: very explicitly no the lowest value (0.02 g.kg -1 P 2 O 5 ) and block III the highest value (0.035 g.kg -1 P 2 O 5 ). CEC
	showed similar differences among blocks as clay content and Corg: the lowest value was
	measured in block III (9.5 cmol.kg -1 ). Exch. Ca, Na and Mg followed the CEC pattern; K, H
	and Al reached the highest values in block III. Extractable copper (EDTA) had the lowest
	value in block I.

  [START_REF]Liming alone decreased soil moisture and increased water potential probably due to effects on pore space, inducing better water drainage and better structure[END_REF].17, stable OM represented the main part of total Corg (about 83% in upper layer and nearly 99% in deeper layer), for this reason only active organic compartments are presented (BM and LOM). Lime (without Compo guano) increased active Corg, while in combination with Compo guano, liming decreased active Corg. Compo guano slightly increased part of labile Corg, especially LOM (more evident without liming). The expected effect of lime was not clear with Compo guano due to their interaction.

  4.20). Significantly higher values of Cmin were noticed in the upper soil layer.

	500	BM (mg Ckg -1 )
	450			437				420
	400	381									387
	300 350	314		311				285		283
	250												0-15 cm
	200												15-30 cm
	150
	100
	50
	0
		no lime (5)	lime (10)			no lime (1)		lime (6)
		no Compo guano					Compo guano
			No Compo guano,	No Compo guano,	Compo guano,	Compo guano,
	Soil depth (cm)	no lime (5) 0-15 LOM (mg Ckg -1 ) 15-30	lime (10) 0-15 cm 0-15 15-30	no lime (1) 0-15 15-30	lime (6) 0-15 15-30
	4000 spec. resp. (day -1 )	0,019	0,021	0,022	0,023	0,031	0,027	0,024	0,027
	3500 1*(spec. respir.) -1 (day)	3233	62	56	3211	47	49	3367	32	3337 38	43	44
	3000
	2500
	2000
	1500
	1000
	500
	0
		no lime (5)	lime (10)		no lime (1)	lime (6)
			no Compo guano					Compo guano

Fig. 4.20: Cmin at Pohorski dvor, September 2004. Tab. 4.6: Spec. respiration (day -1 ) and time of turnover (day); Pohorski dvor, September 2004.

  Cmin at Pohorski dvor, May 2005. Spec. respiration (day -1 ) and time of turnover (day) at Pohorski dvor, May 2005.

	600	BM (mg Ckg -1 )	538			562
	500	498			462
	400	346	385			380
	300					256			0-15 cm
	200								15-30 cm
	100
	0
		no lime (5)	lime (10)	no lime (1)	lime (6)
	no Compo guano Fig. 4.23: Tab. 4.7: No Compo guano,	Compo guano No Compo guano, Compo guano,	Compo guano,
			no lime (5)	lime (10)	no lime (1)	lime (6)
	Soil depth (cm)	0-15	15-30	0-15	15-30	0-15	15-30	0-15	15-30
	spec. resp. (day -1 )	0.029	0.030	0.041	0.028	0.024	0.026	0.028	0.027
	1*(spec. respir.) -1 (day)	35	34	25	36	42	40	36	37
		4000	3726	LOM (mg Ckg -1 )	3528		3519
		3500
		3000		2716
		2500
		2000
		1500
		1000
		500
		0
			no lime (5)	lime (10)	no lime (1)	lime (6)
			no Compo guano		Compo guano
	4.23 can be noticed that liming (without Compo guano) decreased mineralisation, probably
	due to a decrease of LOM. With the addition of Compo guano, the situation was the opposite,
	liming increased C mineralisation.
	The upper soil layer contained significantly more Cmin.

Annex 6 : Measurements of water potential (hPa) in Pohorski dvor in 2004 and 2005

			Treat. 5 (pure control)	Treat. 10 (liming only)		Inter-row
	depth (cm) Day no.	20-25	40-45	80-85	20-25	40-45	80-85	20-25	40-45	80-85
			Date						Block I
	15.6.2004	1	-52.0	-46.3	-34.7	-55.0	-39.0	-35.0	-55.0	-53.0	-47.0
	22.6.2004	7	-41.0	-25.0	-33.0	-43	-29	-27	-52	-44	-36
	28.6.2004

Annex 7 : Physical organic matter fractionation and the results of Corg and C/N in each fraction in Gačnik, October 2004.

	Annex 8 :
	Treat.	Slope	Depth	Fract.	Fract.	CaCO3	Corg in	C/N
			(cm)		in soil	in fract.	fract.
					%	%	%
	IRR	downslope	0-5	A	3.9	3.06	14.55	18.5
				B	8.7	7.13	5.05	12.5
				C	87.4	73.20	1.58	6.9
			5-15	A	3.4	2.51	4.00	12.8
				B	9.0	7.43	3.09	10.9
				C	87.6	71.62	1.32	6.5
			15-30	A	1.7	0.19	15.57	32.4
				B	7.1	5.38	3.86	12.4
				C	91.2	74.57	1.39	6.9
		midslope	0-5	A	3.5	1.36	19.44	21.8
				B	7.0	5.22	6.76	13.2
				C	89.5	74.53	1.6	6.8
			5-15	A	0.8	0.05	4.35	16.4
				B	7.2	5.69	3.17	11.9
				C	92.0	73.44	1.15	6.3
			15-30	A	1.3	0.05	7.72	20.8
				B	8.8	7.08	3.46	11.5
				C	89.9	73.56	1.52	7.0
		upslope	0-5	A	2.4	0.92	4.63	12.6
				B	6.0	4.30	2.55	10.5
				C	91.6	65.28	0.73	4.4
			5-15	A B C	1.2 7.1 91.8	2.84 62.67	8.08 1.58 0.59	26.1 9.7 4.1
			15-30	A	1.2	0.13	10.37	32.4
				B	6.5	4.49	1.38	9.5
				C	92.2	63.49	0.50	3.6
	NIR	downslope	0-5	A	4.3	3.36	5.21	12.3
				B	10.2	8.84	3.73	11.8
				C	85.6	72.14	1.51	6.7
			5-15	A	2.2	0.94	4.93	17.1
				B	7.3	5.99	2.99	10.7
				C	90.5	73.25	1.49	7.6
			15-30	A	3.4	2.01	4.27	16.2
				B	7.2	5.80	3.29	10.9
				C	89.4	71.08	1.42	7.3
		midslope	0-5	A	2.5	1.08	7.99	15.4
				B	7.9	6.45	3.53	15.2
				C	89.7	76.05	1.36	6.5
			5-15	A	2.1	0.52	3.61	13.5
				B	8.5	6.92	2.90	10.5
				C	89.5	74.81	1.42	7.3
			15-30	A	2.2	0.58	3.78	13.2
				B	7.6	6.04	2.67	10.1
				C	90.2	74.19	1.19	6.7
		upslope	0-5	A	2.2	0.66	7.25	15.4
				B	7.9	5.79	1.99	9.4
				C	89.9	64.86	0.71	4.1
			5-15	A	2.3	0.59	7.03	17.4
				B	9.0	6.27	2.11	8.6
				C	88.8	63.33	0.86	5.0
			15-30	A	1.5	0.18	5.46	18.3
				B	11.5	8.35	0.82	5.0
				C	87.1	61.63	0.51	3.5

Sedimentary and fresh organic carbon stocks (0-30 cm) according to size fraction, slope position and treatments in Gačnik, October 2004. Fraction size Slope position Treatment

										content (W) in Gačnik, 2005.
														May 2005
	depth			Biomass					Cmin				LOM					W	pH
	(cm) Treat. Sun e 0-15 15-30	# 537 415	IRR	(mg Ckg -1 ) ☼ # 542 472	NIR	☼ 545 420	# 273 308	IRR	(mg Ckg -1 ) ☼ # 235 214	NIR	☼	IRR 1528 #	Sedimentary Organic Carbon Stock T.ha-1 (mg Ckg -1 ) NIR IRR ☼ # ☼ # Downslope 1326 2830 2775 32.3 34.6	(%) Organic Fresh NIR # ☼ Carbon Stock ☼ T.ha-1 27.7 31.7 27.3 31.3 34 28.5	IRR Total Organic NIR ☼ # ☼ Carbon Stock 7.59 # 7.62 7.75 7.74 T.ha-1 7.8 7.82 7.76 7.73
												NIR			1.48				3.21	4.69
						Upslope
												IRR			1.69				2.47	4.16
												NIR			0.57				3.27	3.84
		A				Midslope
												IRR			0.51				5.93	6.44
												NIR			1.27				4.33	5.60
					Downslope
												IRR			5.92				4.09	10.01
	0-15	391			387		400	86		82	288	NIR 286	507	Upslope 468 1511	2.83 1506	25.1		22.3	2.41 26.5	24	7.82	5.24 7.77 7.95	7.89
	15-30	223			183	217 Upslope # shady side				IRR			2.44	26.3		23.6	28.9 1.53 ☼ sunny side 24.6	8.04	7.96 3.97 7.9	7.89
														September 2005
	depth (cm) Treat.	B	IRR	Biomass (mg Ckg -1 )	Midslope NIR	IRR	Cmin (mg Ckg -1 )	NIR NIR	IRR	LOM (mg Ckg -1 )	2.27 NIR	IRR			W (%)	6.55 NIR	IRR	pH 8.82	NIR
	Sun e	#		☼	#		☼	#		☼	#	IRR ☼	#	☼ Downslope #	2.26 ☼	#		☼	9.03 #	☼	#	☼ 11.29 #	☼
	0-15	189			223		219	1 260		3 281	2 278	NIR 2 252			2.64	33.6	31.4	7.12 38.1	4 31.	7.7	9.76 7.68 7.78	7.72
	15-30	205			242 Downslope 162				IRR		Midslope	3.58	34.7	31.1	39.2 7.56	31. 8	7.73	7.78 11.14 7.83	7.81
	0-15	156			216		196	236		239	274		245				36	32.4	27.2	31.	7.8	7.81	7.76	7.74
	15-30	206			262		201	3		8	2	NIR 2			17.81	35	32.8	4.53 34.7	1 31.	7.81	22.34 7.81 7.78	7.77
	0-15	153			252	Upslope 192 113		885	184	IRR 147		Upslope	17.45	26.9	24.4	1.75 31.4	5 25.	7.83	19.20 7.8 7.79	7.74
								4			3		2							6
	15-30	C 153			177	148 Midslope # shady side				NIR			23.72	27	25.8	20.87 30 24. 9 ☼ sunny side	7.83	7.83 44.59 7.85	7.81
												IRR			21.30				25.55	46.85
												NIR			25.67				24.13	49.80
					Downslope
												IRR			24.54				21.38	45.92

Studied site with irrigation

July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 July, 06 II.1.2 Location Pohorski dvor For better review, the full list of completed soil samples in Pohorski dvor, collected from

ACKNOWLEDGEMENTS

During the preparation of my Ph.D. thesis, under French-Slovenian co-mentorship, I was lucky to work with kind, knowledgeable, experienced and enthusiastic people. I would like to thank all of them for their generosity and kindness. Particularly, I am grateful to the following people: May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 May 04 Microbiological characterisations: (Humidity, pH) Biomass Cmin LOM May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04, 05 May, Sept. 04 N• aer./anaer. bacteria N• fungi N•coliforms HEV, Rota July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06 July, Oct. 06

Glede na naklon terena, so se gravimetrična vsebnost vode (W), vsebnost organske snovi (OM) in mikrobne biomase (MB) ter nivo mikrobnega dihanja (R) večali v smeri proti vznožju pobočja, medtem ko so se skupni karbonati SWRC -Soil Water Retention Curve TBS -tetrabromo-2-benzotriazole TOC -Total Organic Carbon USEPA -United States Environmental Protection Agency W -gravimetric water content WHO -World Health Organization

Prof. Dr. Pierre Curmi, for the supervision of my thesis on the French side, for precise revision of my work and for constructive discussions.

Prof. Dr. Avrelija Cencič, for the supervision of my thesis on the Slovene side, constructive discussions and helpful advice concerning specific microbial analyses and international administration.

Dr. Rémi Chaussod, for being co-supervisor, for encouragement and for welcoming me in his laboratory, for his kind help in preparing the thesis and work with microorganisms.