Amplitude and frequency of wetting and drying cycles drive N2 and N2O emissions from a subtropical pasture

Summary

Abstract This study investigated the effects of irrigation frequency on N 2 and N 2 O emissions from an intensively managed pasture in the subtropics. Irrigation volumes were estimated to replace evapotranspiration and were applied either once (low frequency) or split into four applications (high frequency). To test for legacy effects, a large rainfall event was simulated at the end of the experiment. Over 15 days, 7.9 ± 2.7 kg N 2 + N 2 O-N ha −1 was emitted on average regardless of irrigation frequency, with N 2 O accounting for 25% of overall N 2 + N 2 O. Repeated, small amounts of irrigation produced an equal amount of N 2 + N 2 O losses as a single, large irrigation event. The increase in N 2 O emissions after the large rainfall event was smaller in the high-frequency treatment, shift