Biological production and consumption of nitrous oxide in soils

Nitrous oxide (N(2)O) may be produced in the soil by both abiotic and biotic processes, with the contributions from biotic processes being more significant. The major direct, biotic sources of N(2)O are denitrification and nitrification, although nitrifying bacteria also make an indirect contribution, because the NO, produced may be subject to denitrification. N(2)O is both produced and consumed by the process of denitrification, and the balance between production and consumption determines net N(2)O production. In this paper, the biological processes of N(2)O production, the approaches to determining the contributions from these different sources, and the way in which the different interactings processes influence overall N(2)O emission are outlined. (C) Elsevier, Paris.