Objectives In order to provide a theoretical basis for green and efficient management of irrigation and nitrogen, the effects of the different water and nitrogen application models on ammonia volatilization, rice yield, and nitrogen use efficiency and the relationship between ammonia volatilization (AV) and rice yield as well as nitrogen absorption and translocation were studied.

Methods A field experiment was conducted in Shenyang, Liaoning province from 2021 to 2022. The experiment used the rice cultivar Shendao 47 as experimental material, set up two irrigation regimes (W1, flood irrigation; W2, alternate wet and dry irrigation) and four nitrogen application modes (N0, no nitrogen fertilizer; N1, 100% controlled release urea one-time basal application; N2, 80% controlled release urea + 20% common urea one-time basal application; N3, 100% common urea split fertilization). The ammonia volatilization, soil nitrogen content, rice yield and nitrogen absorption and utilization under different water and nitrogen application models were measured.

Results (1) W2 significantly increased the rice yield of each treatment in relative to that under W1 conditions. Under both W1 and W2, rice yield under N2 treatment was higher than the other treatments, which was mainly attributed to the increased effective panicles, spikelet per panicle and seed-setting rate. (2) The two irrigation regimes had different effects on nitrogen accumulation and translocation in rice. Compared to W1, the W2 significantly increased the nitrogen accumulation of stem-sheath, leaf and whole plant at heading stage, the nitrogen translocation amount and contribution rate of nitrogen translocation to panicle from heading stage to maturity stage for all nitrogen application treatments. Specifically, under the W1, there were no significant differences in the above indicators among the various nitrogen application treatments; however, under the W2, these indicators in the N2 treatment were significantly higher than those in the N1 and N3 treatments, which subsequently significantly improved nitrogen apparent recovery efficiency and nitrogen agronomic efficiency. (3) W2 significantly reduced the total AV compared with W1. Under both irrigation regimes, N1 and N2 decreased the total AV by 15.31%−33.21% and 7.97%−38.09%, respectively, relative to N3, with the most significant decrease at the first top-dressing stage. On the one hand, the N1 and N2 treatments reduced the peak concentration of soil NH+ 4-N after fertilization, directly decreased the AV substrate; on the other hand, they increased the soil NH+ 4-N and NO- 3-N content during the middle and late growth stages, which in turn increased the maximum rate of N accumulation, shortened the lasting period for rapid N accumulation, enhanced the absorption of soil nitrogen by rice plants, and shortened the nitrogen retention time, thus indirectly inhibiting AV loss. (4) Rice yield was significantly and positively correlated with total N accumulation at heading, grain-filling, and maturity stages, N translocation parameters (e.g. amount, rate, and contribution rate), and nitrogen use efficiency. All these indicators showed significant and negative correlations with the AV loss. It indicated that appropriate water and nitrogen management could effectively mitigate AV loss, collaboratively improve N absorption and translocation, which significantly improved rice yield and nitrogen use efficiency.

Conclusions Given the results of grain yield, nitrogen absorption and utilization, and AV characteristics in rice paddy of the two years, alternating wet and dry irrigation (W2) was more conducive to exploiting the synergistic advantages of water and nitrogen than flood irrigation (W1). Among the combinations, alternating wet and dry irrigation (W2) coupled with 80% controlled-release urea + 20% conventional urea (N2) one-time basal application (W2N2) exhibited the most prominent comprehensive effect. This water–nitrogen combination could effectively improve the fluency of the nitrogen absorption-translocation in rice, and synergistically increase rice yield and nitrogen use efficiency, and significantly reduced AV loss. It can serve as a suitable water and nitrogen management regimes for the green, efficient and simplified rice cultivation.