Le protoxyde d’azote (N2O), puissant gaz à effet de serre émis par les sols agricoles : méthodes d’inventaire et leviers de réduction

Abstract

Nitrous oxide (N2O) is a greenhouse gas that mainly originates from soils and agricultural activities. International initiatives require that countries calculate national inventories of their N2O emissions from agricultural soils. Several methodologies can be applied: (i) Tier I Intergovernmental Panel on Climate Change (IPCC) default approach that only takes into account nitrogen (N) input, (ii) Country-specific methodologies (Tier II and Tier III) that account for regional climatic and land use impacts on N2O emission factors, and include several sources. Strategies to mitigate N2O emissions from agricultural soils are based on a rational use of N resource and the stimulation of soil aerobic conditions and biological activity. Management practices to reduce the N2O emissions should be focused on: (i) Avoiding the soil denitrification process by maximizing soil aeration and reducing their acidity, (ii) Improving N fertilization by reducing free N in soil and optimizing N use efficiency in cropping systems, (iii) Direct actions on the microbial processes by limiting the nitrification process and stimulating the last step of the denitrification process (N2O reduction to N2).

Keywords

• nitrous oxide
• greenhouse gas
• agricultural soils
• emission inventories
• mitigation pathways