Parameterizing an agricultural production model for simulating nitrous oxide emissions in a wheat-maize system in the North China Plain

Concentrations of atmospheric nitrous oxide (N 2 O), a potent greenhouse gas, have been continuously increasing, and cropland soils are one of the largest sources of N 2 O. Variations in environmental and anthropogenic factors have substantial impacts on both the frequency and magnitude of N 2 O emissions. Based on measurements from a wheat-maize system in the North China Plain, the authors parameterized the Agricultural Production Systems Simulator (APSIM) model, which was initially developed in Australia, for simulating N 2 O emissions under different agricultural management practices. After calibrating one of the key parameters - the fraction of N 2 O lost in nitrification (k 2 ) - the results showed that the model successfully captured the daily N 2 O fluxes under different nitrogen fertilization treatments, but underestimated some large peak fluxes. By pooling all data together, the calibrated APSIM model also performed well in representing cumulative N 2 O emissions under various treatments at annual and finer (monthly and daily) time scales.