Pablo Raguet

Alain Mollier

Noura Ziadi

Sabine Houot

Denis Montenach

Antoine Karam

Christian Morel

Dynamic of organic phosphorus in the plough soil layer of three contrasting long-term field experiments

► Soil Organic Phosphorus (SOP): ≈ 30 % of total phosphorus (P) ► Few long-term studies in field conditions on SOP dynamics ► No information on SOP gross mineralization Cropped soils over decades, ploughed layer Conceptual diagram of the Hénin-Dupuis model in Andriulo et al 1999: consider two C pools. k 1 = humification rate of crop residues, k 2 = mineralization rate of soil organic matter .02 Materials & Methods ► Quantification of SOP annual gross mineralization rate Modeling on time series data Over several decades 3 long-term field experiments (4 replicates per treatments) Different field conditions Study aims .

Introduction

Results & discussion Conclusions CO 2 Mean annual yield (t ha

Humus C Residues

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  Pablo Raguet -CSSS-ASSW congress session 15 -24 May 2022 ► Extensive literature on soil organic carbon speciation, dynamic and modeling (Andriulo et al 1999, Clivot et al 2019, Hénin and Dupuis 1945)  model adaptation to SOP: Annual time step Simulation over decades Cropped field conditions Introduction Results & discussion Conclusions Qualiagro field map ► Assessment of fertilization practices effects on SOP gross mineralization Organic waste products fertilization (OWP) Mineral fertilization Pablo Raguet -CSSS-ASSW congress session 15 -24 May 2022 Long-term field experiments S3 Continental; eutric brunisol; corn-wheat-sugar beet-barley ; 14 years; 6 soil samplings; pH = 8.3 Treatments and P inputs (kg P ha -1 an -1 ):  Control (8)  Farm yard manure (21)  Composted farm yard manure (21)  Biowaste (17)  Urban sewage sludge (36)  Green waste and sewage sludge (45) S2 Oceanic ; luvisol; corn-wheat; 18 years; 7 soil samplings; pH = 7.1 Treatments and P inputs (kg P ha -1 an -1 ):  Control (5)  Municipal solid waste (24)  Farm yard manure (28)  Biowaste (44)  Green waste and sewage sludge (106) S1 Oceanic ; sandy soil ; maize monoculture 17 years ; 4 soil samplings; pH = 7and some years in S1) P concentration in aboveground residues Pablo Raguet -CSSS-ASSW congress session 15 -24 May 2022 ► Derivative equation: with : i: P input source (3 types of crop residues, OWP) Pi (kg ha -1 y -1 ): amount of organic P input within i hi: incorporation coefficient of Pi to SOP during 1 year K (y -1 ): gross mineralization coefficient of SOP Model description ► SOP dynamic = balance between: 1) P incorporation to SOP 2) SOP mineralization Annual time step ► Products P inputs the year following fertilization: Unknown parameter: K Optimized (reduce the sum of square) ► gross annual rate of mineralization = K x SOP (kg P ha -1 y -1 ) ► Net SOP stock variation evaluated with linear regression Pablo Raguet -CSSS-ASSW congress session 15 -24 May 2022 S1 S2 S3

Pablo Raguet -CSSS-ASSW congress session 15 -24 May 2022

Model calculation

► Known parameters: Pi : measured in OWP and calculated for:

SOP stocks variation between sites and treatments

► Variations (= slope) (kg P ha -1 y -1 ):

Measured SOP and each site linear regression on SOP stocks in the ploughed soil layer as affected by P fertilization along all three sites.

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Materials & Methods Introduction

Results & discussion