Abstract
The application of urease inhibitors (UIs) and optimizing nitrogen (N) split application ratio (NSR) can both minimize ammonia (NH(3)) volatilization and increase rice yield. However, few studies have analyzed the combined effects of these two practices with straw returning on rice yield and NH(3) volatilization. In this study, based on a field experiment involving rice yield, aboveground dry matter (ADM), crop N uptake (N(upt)), and NH(3) volatilization from 2018 to 2019 in Sichuan Basin, China, the WHCNS (soil water heat carbon nitrogen simulator) model was used to simulate the effects of straw returning, UI, and NSR on rice growth and NH(3) volatilization. The results showed that the WHCNS model performed well in simulating rice growth and NH(3) volatilization. With straw return amount exceeding 4 t ha(-1), rice yield increased slowly or stabilized, while N(upt) and NH(3) volatilization continued to increase. Increasing the panicle fertilizer (PF) proportion enhanced N(upt) during the PF stage, thereby promoting yield improvement. The NSR(3) (a 1:1:3 ratio of base fertilizer, tiller fertilizer, and PF) achieved the highest yield, exceeding that of 2:1:2 by 0.29, 0.23, and 0.08 t ha(-1) at straw return amounts of 2, 3, and 4 t ha(-1), respectively. However, the effects of UI on N(upt) and yield enhancement were limited. Furthermore, optimized NSR and the application of UI reduced NH(3) volatilization during the basal or tiller fertilizer stages, leading to an average decrease of 5.5% and 8.5% in total NH(3) volatilization, respectively. Meanwhile, the increase in straw return amount reduced the NH(3) volatilization reduction effects of both practices. Overall, the combination of NSR(3) and UI with the straw return amount of 3 t ha(-1) was the optimal practice for balancing food security and environmental benefits in purple soil area.