Temporal changes in N2O efflux from cropped and fallow agricultural fields

Nitrous oxide (N2O) is implicated in both global warming and catalytic destruction of stratospheric ozone layer. Although, its atmospheric abundance is increasing unabated due to intensification of agricultural activities in recent years, but the estimates of both source and sink strengths of N2O are still highly uncertain. This study was conducted to measure seasonal variation in N2O efflux from the cropped and fallow fields with different levels of fertilizer application and moisture regimes. There was a pulse in N2O emission after the application of N-fertilizer and also after irrigation. This indicated that N2O production was stimulated either by nitrifying bacteria with addition of NH4+ as the substrate in oxic condition or by denitrifying bacteria in partial anoxic condition created by irrigation. Besides, emission of more N2O from the cropped than fallow fields, with the same treatments of chemical fertilizers and irrigation, underlined the importance of plants in transportation of N2O from the rhizosphere to troposphere. This observation indicates that the plants have also a transport pathway of N2O as reported in the case of CH4 transport through aquatic plants.