管渠自动控水灌溉施氮量对夏玉米产量、氮素吸收利用的影响

目的]寻找管渠自动控水灌溉夏玉米的最佳施氮量。方法]设置畦灌(B)和管渠自动控水灌溉(W)2种灌水模式①畦灌采用传统施氮量(300 kg/hm^2,N1);②管渠自动控水灌溉设置;农民传统施氮(300 kg/hm^2,N1)、减氮25%(225 kg/hm^2,N2)、减氮50%(150 kg/hm^2,N3)和不施氮(N0)处理。测定不同处理夏玉米抽雄期和完熟期的营养器官干物质积累量和氮素积累量,并对花后干物质积累量、氮素转运量及转运效率、氮肥的利用效率进行分析比较。结果]施氮量为300kg/hm^2时,W灌水模式相较于B灌水模式籽粒产量和完熟期干物质积累量分别提高5.46%和3.23%,氮素总积累量和氮肥利用率分别提高7.79%和26.69%。W灌水模式下,减氮25%处理籽粒产量、籽粒氮素积累量和植株氮素积累量与畦灌传统施氮处理无显著差异,且氮素利用率显著提高25.54%,减氮50%处理氮肥偏生产力显著高于其他处理。结论]在管渠自动控水灌溉情况下可以考虑适当减少氮肥的施用量,将氮肥施用量控制在225~300 kg/hm^2之间。

Effects of Nitrogen Application on Yield,Nitrogen Uptake and Utilization by Summer Maize under Automatically Controlled Pipe-channel Irrigation

Background]Surface irrigation is the dominant irrigation method in world including China despite its poor irrigation uniformity. Although efforts have been made in many countries to improve surface irrigation technology, progresses are still being made. Automatic pipe-channel irrigation is an irrigation technology that not only reduces irrigation time but also saves water. It can calculate the amount of water required in each field and control the irrigation accuracy along the irrigation furrow to alleviate water leakage loss and improve irrigation uniformity. In China, nitrogen fertilizers contribute 40% to 60% to the increased crop yields in China, but their use efficiency is only 30%, far lower than the international average. Meanwhile, continuous increase in nitrogen fertilizer application has led to detrimental impact on environment, largely due to the inappropriate combination of irrigation and fertilization.Objective]The purpose of this paper is to experimentally seek an optimal nitrogen application for maize irrigated with automatically controlled pipe-channel irrigation. Method] We compared border irrigation(B) and the automatic pipe-channel irrigation(W). Nitrogen fertilizer used in the border irrigation was 300 kg/hm^2, the same as used by local farmers. In the automatically controlling pipe-channel irrigation, we compared three nitrogen fertilizations: 300 kg/hm^2(N1), 225 kg/hm^2(N2) and 150 kg/hm^2(N3), with no nitrogen fertilization as the control(N0). At the tasseling and full ripeness stages we measured the dry matter accumulation in the vegetative organs, while after the flowering stage we measured the nitrogen accumulation, dry matter accumulation, nitrogen translocation, and nitrogen use efficiency.Result]When nitrogen application was 300 kg/hm^2, W irrigation increased grain yield and dry matter accumulation at mature stage by 5.46% and 3.23%, and total nitrogen accumulation and nitrogen use efficiency by 7.79% and 26.69% respectively, compared to B irrigation. Coupled with W irrigation, N1, N2 and N3 nitrogen application increased proportion of dry matter at mature stage compared to the control, but did not show significant difference in grain yield, nitrogen accumulation in the grain and the plant despite the reduced nitrogen application in N2 and N3 Reducing nitrogen application therefore increased nitrogen use efficiency significantly by up to 25.54%. The partial productivity of nitrogen in N3 was significantly higher than that in other treatments. Conclusion]Coupling fertilization and automatic pipe-channel irrigation can reduce nitrogen fertilizer application, and for the experiments we conduced, the application rate can be controlled in 225 kg/hm^2 to 300 kg/hm^2 without scarifying grain yield and quality.