Effect of precipitation and nitrogen application on spring wheat yield in dryland based on APSIM model

The aim of the present study was to investigate the effects of water and nitrogen on the yield of spring wheat in the middle Loess Plateau of Gansu Province, China. Using experimental field data and the Agricultural Production System Simulator (APSIM), precipitation and nitrogen application gradients were established. The results demonstrated that the APSIM model was highly accurate for simulating spring wheat yield; the determinant coefficient, normalized root mean square error, and model consistency index were 0.95, 27.36%, and 0.91, respectively. Furthermore, the yield of spring wheat first increased and then decreased with increases in precipitation or nitrogen application. The maximum mean yield (5 406.64 kg·ha^–1) was observed at 20% precipitation and a nitrogen application rate of 157.5 kg·ha^–1. However, according to the curve fitting equation for yield variation, yield would be maximized (5 988 kg·ha^–1) at 55% precipitation and a nitrogen application rate of 257.25 kg·ha^–1.