Laboratory kinetics of soil denitrification are useful to discriminate soils with potentially high levels of N2O emission on the field scale

Emissions of N2O, a greenhouse gas, were measured in field conditions on a Rendzic Leptosol, an Eutric Leptosol, a Haplic Calcisol, a Haplic Luvisol and two Gleyic Luvisols under cultivation, and on a Haplic Fluvisol and two Gleyic Cambisols under cultivation and grassland conditions. The kinetics of N2O production and consumption during denitrification in these soils were studied during anaerobic incubations in the laboratory, with NO3- and N2O addition in the presence or absence of acetylene. The soils with the highest "in situ" levels of N2O emission, i.e. the Gleyic Luvisols under cultivation and the grassland soils, exhibited considerable transient accumulation of N2O during denitrification studied in the laboratory. We therefore propose an empirical indicator, measured in the laboratory, of the soil's potential to emit N2O on the field scale. Carbon addition to one of the Gleyic Luvisols promoted N2O reduction and limited the transient accumulation of N2O during laboratory denitrification.