水氮互作对滴灌夏玉米生长及水分利用效率的影响

【目的】在保证夏玉米高产情况下实现节水节肥。【方法】采用滴灌,研究不同补灌处理(2018年测墒土层为0~20、0~30和0~40cm,依次记为W20、W30和W40,2019年测墒土层增加0~10cm,记为W10;补灌时期均为播种时及拔节期和抽雄期开始时,目标含水率为田间持水率和不同施氮量处理(2018年施氮量为180、240和300kg/hm^2,分别以N180、N240和N300表示,2019年施氮量增加120 kg/hm^2,记作N120;施氮与灌水时期一致)相组合对夏玉米叶面积指数(LAI)、地上部干物质量、产量构成、耗水量和水分利用效率(WUE)的影响。【结果】LAI和地上部干物质量随灌水量和施氮量增加均呈增大趋势,各补灌条件下,N240和N300处理间差异不显著。施氮量对夏玉米产量的影响效应大于灌水量和水氮互作,2018年仅W20N180处理的产量显著低于高水高氮(W40N300)处理;2019年仅W10灌水条件下所有施氮处理以及W20、W30和W40条件下N120处理的产量显著低于W40N300处理。灌水量和施氮量均对耗水量具有极显著影响,耗水量随施氮量和灌水量的增加呈增大趋势;灌水处理对WUE产生极显著影响,2018年W20和W30条件下,各处理WUE均值较W40分别提高11.05%和1.74%,2019年W10、W20和W30条件下各处理WUE均值较W40依次提高17.94%、9.11%和7.21%。【结论】试验区夏玉米滴灌条件下适宜的水氮施用方案为:补灌/施氮时期为播种时及拔节期和抽雄期开始时,目标湿润土层0~20 cm,补灌上限为田间持水率;施氮量180~240kg/hm2,施氮比例为1∶1∶1,播种时氮肥底施,拔节和抽雄时氮肥随水施入。

Combined Effects of Water and Nitrogen Application on Growth and Water Use of Summer Maize under Drip Irrigation

【Background】Water scarcity and low fertilizer use efficiency are two problems facing agricultural production in China.Reducing water use and improving nitrogen use efficiency have been mandated by Chinese government in its effort to develop sustainable agriculture.【Objective】The purpose of this paper is to study experimentally the combined effects of water and nitrogen application on root water uptake and growth of summer maize under drip irrigation.【Method】A two-year field experiment was conducted in 2018—2019 under different combinations of irrigation amounts and nitrogen applications.Three were four N treatments:120 kg/hm2(N120,in 2019 only),180 kg/hm2(N180),240 kg/hm2(N240)and 300 kg/hm2(N300).The difference in irrigation treatments was the criterion used to determine the irrigation amount.Plots in all treatments were irrigated at planting,jointing and tasseling stage,with the amount to water in each irrigation calculated as the water required to top up the soil water in 0~10 cm(W10,in 2019 only),0~20 cm(W20),0~30 cm(W30)and 0~40 cm(W40)soil layer to the field capacity,respectively.In each treatment,we measured the leaf area index(LAI),aboveground biomass,yield components,evapotranspiration and water use efficiency(WUE).【Result】The aboveground biomass and LAI both increased with water and N application,but there was no significant difference between N240 and N300.The effect of N application on seed yield was more significant than the combined impact of water and N.In 2018,only was the yield of W20N180 lower than that of W40N300,while in 2019 the yield of all treatments,except W10 coupled with all N treatments and N120 coupled with all irrigation treatments,was comparable to the yield of W40N300.The evapotranspiration increased with water and nitrogen application,and WUE varied with irrigation.Compared to W40,the average WUE in W20 and W30 increased by 11.05%and 1.74%respectively in 2018,and by 9.11%and 7.21%respectively in 2019.【Conclusion】To best balance irrigation amount,N application,grain yield and WUE,the optimal irrigation and fertilization for the summer maize under drip irrigation in this area is:Irrigating and fertilizing at sowing,jointing and tasseling stage by topping up the water content in 0~20 cm soil layer to the field capacity,with 180 to 240 kg/hm^2 of N applied with the irrigations at 1∶1∶1 ratio at the three stages.N in the sowing sage was broadcasted as basal fertilizer.