Field method to determine N2O emission from nitrification and denitrification

Nitrous oxide (N2O) emissions via the nitrification (I-nit) and denitrifica tion (I-den) pathways were successfully measured with in-field incubation o f soil cores in preserving jars at 0 Pa and 5-10 Pa acetylene. From the inc ubations, fractions of nitrification - N2O over total N2O (I-nit/I-tot)- an d denitrification - N2O over total N2O (I-den/I-tot) - were obtained. Actua l field emissions of N2O via nitrification (F-nit) and denitrification (F-d en) were calculated by multiplying the fractions from the incubation techni que with the daily N2O emission (F-day) determined with a direct soil cover method. The approach presented here was successful for a whole range of so il moisture conditions in intensive grassland. F-nit and F-den followed the trends of soil ammonium and soil nitrate.