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

Nitrous oxide (N₂O), a greenhouse gas emitted from agricultural soils: emission inventories and mitigation pathways

¹ UMT GES-N₂O; CETIOM, avenue Lucien Brétignières, 78850 Thiverval-Grignon, France
² INRA, Unité de Science du Sol, 2163 avenue de la Pomme de Pin, CS 40001 Ardon, 45075 Orléans Cedex 2, France
³ Agriculture and Agri-food Canada, 2560 Hochelaga Blvd, Quebec, Quebec G1V 2J3, Canada
⁴ Alterra Wageningen UR, Droevendaalsesteeg 4, 6708PB Wageningen, Pays-Bas
⁵ Département des Etudes Opérationnelles, CETIOM, Avenue Lucien Brétignières, 78850 Thiverval-Grignon, France
⁶ INRA, Unité Mixte de Recherche INRA/AgroParisTech “Environnement et Grandes Cultures”, 78850 Thiverval-Grignon, France

^* amelie.viard@gmail.com

Reçu : 7 Janvier 2013
Accepté : 6 Février 2013

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).