Crop residues moderately influence cumulative N2O emissions through their carbon to nitrogen ratio in a 12-year experiment in northern France

Abstract Crop residues and their management are central to the performance of cropping systems. However, we lack information on the extent to which crop residues influence their N₂O emissions, especially over the long term. This knowledge is key as it determines if benefits from crop residue management such as increased carbon storage or soil and water preservation should be weighed against potential stimulation of N 2 O emissions. To lessen this gap, we investigated the effect of crop residue quantity (dry matter yield ranging from 0.29 to 11 t·ha −1 ) and quality (C:N ranging from 8 to 157) on N 2 O emissions and compared it to the effects of other key drivers related to environmental conditions and management practices, such as soil moisture, temperature, and fertilization. We relied on a 12-year dataset of N 2 O emissions from an arable cropping experiment in northern France and implemented an original approach combining definition of “restitution cycles” and use of both linear regression and machine learning algorithms to predict N 2 O emissions at that scale. This allowed to assess the contribution of the various drivers of these emissions, among which crop residue and their management. Our results show that the main drivers of cumulative N 2 O emissions were the amount of mineral nitrogen fertilizer and restitution cycle length. Crop residue characteristics had a relatively minor effect. Among the residue quality indicators, only crop residue C:N ratio affected N 2 O emissions. Tillage, temperature, and water-filled pore space had no detectable or systematic impact. These findings, which are original in terms of the cropping system scale considered, suggest that crop-residue management is not likely to significantly affect N 2 O emissions from arable cropping systems in northern France. They open up opportunities for agricultural decision-making without concern for increased N 2 O emissions as an unwanted trade-off.