The research line 1 focuses on the agronomical and environmental evaluation of agricultural systems, and deals in particular with the issues of integrating or spatially extending physicochemical and ecophysiological processes studied at finer scales. It relies on a common set of methodologies including scale change, model coupling, sensitivity analysis, meta-modeling, and inverse modeling. Some of them enable a transfer of results obtained under controlled conditions to real life situations at field or landscape scale. A prime objective of this research line is to answer finalized questions on strategies and levers of action to maintain agricultural production while minimizing its environmental and health impacts. Levers are: varietal selection, optimization of crop management, changes in land use, landscape planning, and possibly evolutions at territorial level. Their evaluation is generally done by defining and calculating indicators (environmental, agronomic or health), which makes it possible to identify strategies that enhance the performance of agroecosystems and the services they provide. This theme provides new references on GHG and contaminants emissions by agriculture in France and Europe that contributes to public decisions.
During the last 5-year period, we contributed to:
- Integrate genotype-environment interactions at the crop scale. Studies at the individual plant level were integrated into crop models to refine the description of varietal differences. Wheat and brown-rust interactions have been introduced into agro-ecosystem models to simulate its evolution under climate change (Caubel et al., 2017). Similarly, an epidemic Septoria model was coupled with a plant architecture model, which simulated the intensity of Septoria leaf spot development in a wheat cover for several climate scenarios (Robert et al., 2018).
- Integrate nitrogen cycle processes in the agroecosystem. Studies on genotype-nitrogen interactions at the plant level helped quantifying the genetic variability of NUE (nitrogen utilization efficiency) (Richard-Molard et al., 2015). This parameter was used in larger-scale models, such as crop and nitrogen emission models, life- cycle assessments of crops and bio-based products (Dufossé et al., 2016).
- Map trace-gas fluxes at regional and national scales. Emission and deposition of reactive nitrogen compounds (NH3, N2O), greenhouse gases (N2O), ozone (O3), and pesticides were integrated beyond the plot scale (territories in the broad sense: landscape, region, or country). The volatilization of NH3 was mapped at the national scale using the process-based model Volt’air to better evaluate ammonium nitrate aerosol formation (Hamaoui-Laguel et al., 2014; Ramanantenasoa et al., 2018). Similarly, N2O emissions from cropland were estimated over France with the agro-ecosystem model CERES-EGC, and used as a prior in an atmospheric inversion study. Emissions were about half lower than expected with simpler equations used in national reporting (Gabrielle et al., 2014). At landscape scale, Bureau et al. (2017) demonstrated that a combination of static chambers and eddy covariance monitoring enabled mapping N2O emissions at the field scale. These studies contributed to the definition of public policies (anticipation of pollution peaks) or the optimization of nitrogen fertilization (Ben Aoun et al., 2016).
- Analyze landscape interactions. The Nitroscape model was used to study the interactions between nitrogen transfers in the soil, the atmosphere and the hydrological system at the landscape scale, and showed that catch crops useful for reducing both NO3 leaching and N2O emissions while maintaining production (Franqueville et al., 2018; Laurent and Drouet, 2018). A similar approach which couples atmospheric, soil and hydrological transfer of pesticides was started to being developed (MIPP project). A similar approach was recently applied to study spatial interactions due to pathogen dispersion at the landscape scale (P.A. Precigout, PhD, 2018).
- Assess the sustainability of bio-based value-chains and territories. As part of the LOGISTEC project, a holistic framework was developed to model biomass supply chains from energy crops and assess their environmental, economic and social impacts. Application to a real-life case-study in Burgundy (France) pointed at several options to reduce supply costs and life-cycle GHG emissions by up to 30% (Perrin et al., 2017). Metabolism approaches were adapted to analyze the N flows in a semi-urban territory and highlight options to re-couple local food consumption and agricultural production (Tedesco et al., 2017), or characterize the N use efficiency and environmental performance of livestock systems in France.