不同肥力稻田晚稻水氮耦合效应研究

在不同土壤背景氮稻田中，采用不同的水氮管理模式，研究了灌水和施氮方式对晚稻的产量、农艺性状、氮肥利用率及节水效果的影响。结果表明，与淹水灌溉相比，湿润灌溉技术能使晚稻产量提高5.1%~6.5%；土壤氮残留量增加0.4%~2.3%；氮肥农学利用率、吸收利用率、生理利用率分别提高12.6%~113.4%、0.4%~19.7%、11.3%~92.9%，且增幅随着土壤背景氮的上升而提高；节省水资源18.0%~34.3%。施氮方式上，以氮素基肥:追肥为50:50的效果最佳，与农户传统的70:30比例相比，产量提高0.3%~8.9%，并表现出低肥田淹水条件下增幅大、高肥田湿润条件下增幅大的现象；氮肥利用率虽都有一定的提高，但除低肥田外，中、高肥田中差异不显著。试验还发现，氮肥利用率与稻田土壤背景氮呈直线负相关，r = -0.9919；氮肥流失量随着土壤背景氮的增加而上升。研究表明，采用合理的灌溉和施肥，能有效地提高氮肥利用率、增加水稻产量，并节省灌溉用水。但在土壤高背景氮的稻区，最主要的问题是大量减少氮肥用量，以减少氮素流失，降低氮肥对环境的污染。

Analysis of water and nitrogen coupling effects in paddy fields with different fertility levels

Field experiments were conducted to study the effects of different irrigation models and nitrogen application methods on rice yield，agronomic characteristics, nitrogen use efficiency (NUE) and water-saving. The results showed that compared with flooding irrigation, humid irrigation increased rice yield by 5.1%-6.5%, soil residual nitrogen by 0.4%-2.3%, and agronomic N use efficiency (AE) , recovery (RE) and physiology efficiency (PE) by 12.6%~113.4%, 0.4%-19.7%, 11.3%-92.9%，respectively. The increase extents of AE, RE and PE increased with soil background N content. Rice humid irrigation saved water by 18.0%-34.3%. Compared with the traditional model of 70:30 (70% used as basal application and 30% as topdressing), the nitrogen application model of 50:50 (50% used as basal application and 50% as topdressing) increased rice yield by 0.3%-8.9%, with more increase in flooding paddy field. The nitrogen application model of 50:50 increased NUE with different extents, but the increases were not significant in middle-N and high-N fields. In addition, there existed a negative linear correlation between NUE and soil background N content (r = -0.9919), and N loss was enhanced with the increase of soil background N. The results suggested that appropriate irrigation model and nitrogen application method could enhance NUE, increase rice yield and save water effectively. But at present, in some rice production regions with higher soil background N levels, the most important problem is to decrease application rate of N fertilizer, lower N loss, and then reduce N fertilizer pollution to environment.