Performance of the soil-crop model STICS for a wide variety of agronomic and environmental outputs under Belgian pedoclimatic conditions

2. Zero hunger13. Climate actio

Comparing grazing intensities in crop-livestock systems with STICS

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Estimating CO2 fluxes (GPP, RECO, NEE) of diversified crop rotations from STICS outputs

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Integrated crop and livestock systems increase both climate change adaptation and mitigation capacities.

peer reviewedIntegrated crop-livestock systems (ICLS) are proposed as key solutions to the various challenges posed to present-day agriculture which must guarantee high and stable yields while minimizing its impacts on the environment. Yet the complex relationships between crops, grasslands and animals on which they rely demand careful and precise management. In this study, from a 18-year ICLS field experiment in Brazil, that consists in annual no-till soybean-pastures grazed by beef cattle, we investigated the impacts of contrasted pastures grazing intensities (defined by sward heights of 10, 20, 30 and 40 cm, plus an ungrazed treatment) on the agroecosystem productivity and soil organic carbon (SOC) under both historical and future (2040-2070, RCP8.5) climatic conditions. We used an innovative methodology to model the ICLS with the STICS soil-crop model, which was validated with field observations. Results showed that the total system production increased along with grazing intensity because of higher stocking rates and subsequent live weight gains. Moderate and light grazing intensities (30 and 40 cm sward heights) resulted in the largest increase in SOC over the 18-year period, with all ICLS treatments leading to greater SOC contents than the ungrazed treatment. When facing climate change under future conditions, all treatments increased in productivity due to the CO2 fertilization effect and the increases in organic amendments that result from the larger stocking rate allowed by the increased pasture carrying capacity. Moderate grazing resulted in the most significant enhancements in productivity and SOC levels. These improvements were accompanied by increased resistance to both moderate and extreme climatic events, benefiting herbage production and live weight gain. Globally, our results show that adding a trophic level (i.e. herbivores) into cropping systems, provided that their carrying capacities are respected, proved to increase their ability to withstand climate change and to contribute to its mitigation

Analyse prospective de l'évolution des performances agronomiques, environnementales et alimentaires de rotations de cultures contrastées face au changement climatique

peer reviewedFood systems are at the core of multiple negative impacts. In this study, we explore three contrasted crop rotations that were optimized to provide a diet in concordance with the EAT-Lancet reference diet that would be healthy and conform with planetary boundaries: (i) the Business-as-usual (ii) the Vegan and (iii) the Integrated Crop-Livestock systems. By modelling these rotations with the soil-crop model STICS, under historical and future climatic conditions, we compare their agronomic, environmental and nutritional performances and their potential to adapt to and mitigate climate change.Les systèmes alimentaires sont la source de nombreux impacts négatifs. Dans cette étude, nous explorons trois rotations de culture contrastées qui ont été optimisées afin de fournir un régime alimentaire en accord avec le régime de référence du EAT-Lancet, qui serait sain pour l'humain et conforme avec les limites planétaires: les systèmes (i) Business-as-usual (ii) Vegan et (iii) Intégré Cultures-Elevages. En modélisant ces rotations avec le modèle sol-cultures STICS, sous des conditions climatiques historiques et futures, nous comparons leurs performances agronomiques, environnementales et alimentaires ainsi que leur potentiel à s'adapter au changement climatique et à le mitiger.2. Zero hunger12. Responsible consumption and production13. Climate action15. Life on lan

Modelling crop CO2 exchanges to extrapolate ICOS field experiments results

ICOS stations focus on specific agro-pedoclimatic conditions. Calibrated and validated on measured data, modelling studies enable to extrapolate field experiments to contrasted agronomic management or pedoclimatic conditions such as climate change impact. With this goal in mind, we used the outputs of the soil-crop model STICS in its standard pre-parameterized version to model (i) the Gross Primary Productivity (GPP), derived from the autotrophic respiration and the Net Primary Productivity, which is computed through the daily change in plant carbon (C) pools; (ii) the Ecosystem Respiration (RECO), with the autotrophic component being derived from the plant biomass, plant nitrogen concentration and GPP, and the heterotrophic component from the mineralization of residues and organic matter; and (iii) the Net Ecosystem Exchange, equal to the sum of GPP and RECO. The generic approach is transferable to any soil-crop model and was validated on the 16-year crop rotation of the ICOS BE-LON site (winter wheat, sugarbeet, maize, potato, cover crop). The comparison of simulations with field observations indicates that the model is able to simulate accurately daily CO2 fluxes originating from a long-term and diversified crop rotation (efficiency EF equal to 0.79 for GPP, 0.59 for RECO and 0.67 for NEE). Concerning the C budget of the 16-year rotation, the model evaluates it accurately for RECO, with a slight underestimation (normalized deviation ND = 15.7%), and very accurately for GPP (ND = 5.12%). But for NEE, the relative overestimation is higher (ND = 62.2%), indicating that a more precise estimation of HR is required to obtain reliable net C budgets. The model also succeeds to capture the trends in the influence of several environmental drivers on CO2 fluxes. It globally proves to be a valuable tool in the investigation of CO2 exchanges of crop rotations in historical and future climatic conditions

A comprehensive analysis of CO2 exchanges in agro-ecosystems based on a generic soil-crop model-derived methodology

International audienceCarbon emissions in agriculture play a major role in climate change. Modelling studies enable to investigate the impacts of climate change in crops, accounting for soil organic carbon feedbacks and CO2 concentrations. But it is primordial that crop models properly consider the CO2 exchanges at the level of crop rotations beyond the cycle of a single crop. With this goal in mind, we used the outputs of the soil-crop model STICS in its standard pre-parameterized version to model (i) the Gross Primary Productivity (GPP), derived from the autotrophic respiration and the Net Primary Productivity, which is computed through the daily change in plant carbon (C) pools; (ii) the Ecosystem Respiration (RECO), with the autotrophic component being derived from the plant biomass, plant nitrogen concentration and GPP, and the heterotrophic component from the mineralization of residues and organic matter; and (iii) the Net Ecosystem Exchange, equal to the sum of GPP and RECO. The comparison of simulations with field observations indicates that the model is able to simulate accurately daily CO2 fluxes originating from a long-term and diversified crop rotation (efficiency EF equal to 0.79 for GPP, 0.59 for RECO and 0.67 for NEE). Concerning the evaluation of the cumulated fluxes over the 16-year rotation, the model is able to evaluate it accurately for RECO, with a slight underestimation (normalized deviation ND = 15.7%), and very accurately for GPP (ND = 5.12%). But for NEE, the relative overestimation is higher (ND = 62.2%), indicating that a more precise estimation of HR is required to obtain reliable net C budgets. The model also succeeds to capture the trends in the influence of several environmental drivers on CO2 fluxes. It globally proves to be a valuable tool in the investigation of CO2 exchanges of crop rotations in historical and future climatic conditions