Activities in this area concern the environmental assessment of carbon and nitrogen biogeochemical cycles, with refined consideration of gas exchanges (GHG) and their determinants. This work involves studies on the functions of organic matter (contribution to water retention, soil structure and aggregation, soil surface properties), including both soil and crop residues and OWPs. This requests to perform long-term analyses of carbon balances that are not restricted to carbon storage alone. This is a way of managing agroecosystems to be developed, which has been empirical and non- conceptualized until now. In this context, two aspects are specifically addressed in ECOSYS: (1) the regulation of GHG emissions as well as those of aerosols and their precursors (NH3, VOC, NO, O3), C storage in soils and assessment of global warming and (2) local climate regulation (micro- and mesoclimate) with consideration of the impact of landscaping, interactions with water dynamics, and feedbacks between land use and climate.

The objectives of this axis were as follows:

• Identify climate regulation factors at the local level in relation to landscaping and the composition of the plant population.
• Take into account organic matter biodegradation mechanisms at different scales and integrate them into models, addressing the complexity of fine resolutions for incorporation at higher levels of spatial organization.
• Formalize knowledge of denitrification determinism  at the soil structure level in the modeling of GHG emissions.
• Quantify the share of root carbon storage compared to that in aerial parts and identify the mechanisms responsible for different storage dynamics.
• Include GHG emissions and carbon storage in environmental assessments of practices and crop systems (OWP recycling, new cropping systems).

The highlights achievements were as follows:

➢          Coordination of two ANR projects, SOILµ3D (Patricia Garnier, 2015-2020), on the determinism of C and N biotransformations at the microbial habitat scale and integration of abiotic factors in the modeling of GHG emissions at fine resolutions, and SORESOILC (Claire Chenu, 2017-2021) on the potential of agricultural soils to store and stabilize carbon.

➢          Setup and recruitment of an INRA scientist (CR) (Raluca CIURARU, 2015) focusing on physicochemical processes at the interfaces at origin of VOC emissions.

➢          Coordination of the ANR ESCAPADE project (Jean-Louis Drouet, 2013-2017) addressing the nitrogen cascade at the landscape level, including NOx emissions.

➢          Consolidation of existing consortia addressing agriculture-climate interactions: LabEx BASC and FIRE; evolution towards higher-level labeling of the ICOS site; participation in setting up the CLAND Convergence Institute.

➢          Reflection on the role of roots in deep carbon storage: developing a scientific profile and recruiting a CR (Fréderic Rees, 2017).

This axis is managed by Claire Chenu and Benjamin Loubet and is co-driven by the Soil (for carbon-related aspects) and Eco&Phy (for GHG-related aspects) teams, generating 95 and 74 articles, respectively, representing respectively 40 and 50% of the publications of each team. This axis presents strong transversality in the unit, as shown by the 22 publications co-signed by at least two different teams.