Combining field measurements and process‐based modelling to analyse soil tillage and crop residues management impacts on crop production and carbon balance in temperate areas

Crop residues management is an important issue in the context of climate change. They might be kept on the field and restituted to the soil to enhance its fertility or exported for other uses such as the production of energy through biomethanization. Furthermore, the choices regarding tillage operations impact the potential to incorporate residues, which in turn affects soil physical (e.g. structure, water retention), biological (e.g. organic matter, microorganisms) and chemical (e.g. nutrient release through mineralization) fertility. We combined measurements from a 14‐year field experiment in the Hesbaye loamy region of Belgium and its simulation with the STICS soil‐crop model to investigate the impacts of soil tillage and crop residues management on crop production, soil characteristics and carbon balance. Four treatments were compared, where all combinations of the incorporation versus exportation of crop residues and conventional versus reduced tillage were tested. The comparison of field observations with model simulations proved that the STICS model is adequate to explore the impacts of such contrasted management. The combined analysis of field data and soil‐crop model outputs showed that crop production was positively influenced by conventional tillage but unresponsive to crop residues fate. Reduced tillage led to a clear stratification in observed SOC content in the topsoil (0–30 cm), but also to an increase in simulated SOC stocks (0–26 cm). This SOC gain led to greater water retention under reduced tillage. Moreover, in both tillage treatments, incorporating residues increased soil organic carbon despite the associated augmentation in soil heterotrophic respiration. Finally, the importance of environmental conditions in carbon balance suggests that crop modelling might be very useful to explore the impacts of soil tillage and crop residues management in specific agro‐pedoclimatic contexts, especially when facing climate change.