Nitrous oxide contributes to the global greenhouse effect and affects the chemistry of O 3 in the upper troposphere and lower stratosphere. To define a relevant model for microbial NO 3 -and N 2 O reductions in soil and estimate the parameters involved, we propose a method combining measurements of anaerobic soil slurry and simulations of NO 3 -and N 2 O reductions, including non-enzymatic competition between NO 3 -and N 2 O as electron acceptors and the microbial dynamics of two denitrifier groups that are either able or unable to reduce N 2 O. Three models varying in the description of soil capability to reduce N 2 O through denitrification were assessed. The procedure was applied on an arable soil known for its small N 2 O emissions in situ during wet events.