Studies on no and N20 fluxes from a wheat field

The importance of soil parameters and the other environmental conditions that affect emission rates of NO and N20 were studied over a fertilised wheat field. Open-chamber and closed-chamber techniques were used for the flux measurement of NO and N20, respectively. Both gases showed variation in the emission rates which followed the seasonal variation in the available NH4+ and N03− and the moisture content of the soil. Whilst N20 emission rates increased with the moisture content of the soil,NO emissions decreased with increasing soil moisture and rainfall. The results suggested that most soil variables and atmospheric parameters had similar effects on both NO and N2O emission rates but that the overriding influence upon the NOJN2O emission ratio is the soil moisture content. The NO flux showed a clear diurnal variation which followed the surface soil temperature with an activation energy of 108 kJ mol− . The annual NO flux estimated from this study (0.79 kg N ha-−) was approximately half the corresponding N20 (1.42 kg N ha−1).