Imulation of gaseous emissions of nitrogen from organic ley-arable systems under different management regimes

摘要

Nitrogenous gases that result in global warming and the generation of ozone in the troposphere are inevitably emitted to the atmosphere through agricultural activities, but appropriate field practices can reduce the emissions. In a ley-arable system, the time of ploughing and the time of cessation of grazing before ploughing the ley are important variables that determine the fate of mineralised nitrogen. We used the SPACSYS model to simulate N_2 and N_2O emissions under four different management regimes, and compared model output with our experimental data. The results show that the model reasonably simulates N_2O emissions, dry matter accumulation and nitrogen contents in above-ground biomass. Both experimental data and simulation outputs indicate that grazing until early spring (mid-March) and followed immediately by ploughing could cause higher cumulative nitrogenous emissions than autumn cessation of grazing or later ploughing.