The application of urease inhibitors (UIs) and optimizing nitrogen (N) split application ratio (NSR) can both minimize ammonia (NH3) volatilization and increase rice yield. However, few studies have analyzed the combined effects of these two practices with straw returning on rice yield and NH3 volatilization. In this study, based on a field experiment involving rice yield, aboveground dry matter (ADM), crop N uptake (Nupt), and NH3 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 NH3 volatilization. The results showed that the WHCNS model performed well in simulating rice growth and NH3 volatilization. With straw return amount exceeding 4 t ha-1, rice yield increased slowly or stabilized, while Nupt and NH3 volatilization continued to increase. Increasing the panicle fertilizer (PF) proportion enhanced Nupt during the PF stage, thereby promoting yield improvement. The NSR3 (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 Nupt and yield enhancement were limited. Furthermore, optimized NSR and the application of UI reduced NH3 volatilization during the basal or tiller fertilizer stages, leading to an average decrease of 5.5% and 8.5% in total NH3 volatilization, respectively. Meanwhile, the increase in straw return amount reduced the NH3 volatilization reduction effects of both practices. Overall, the combination of NSR3 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.
Keywords: N split application ratio; NH3 volatilization; WHCNS model; rice yield; straw returning; urease inhibitors.