节水减氮对北京地区夏玉米水氮利用的影响

Effects of water saving and nitrogen reduction on the water and nitrogen use efficiency of summer maize in Beijing

针对农业生产中水资源短缺和农业氮肥施用过量问题,探索灌水和施氮与玉米产量、水氮利用和硝态氮积累的关系问题,可为玉米栽培的田间水肥管理提供技术参考。于2019年6—10月在北京开展田间实验和室内分析,设置4个灌水水平(W_(0):0,W_(1):60 mm,W_(2):120 mm和W_(3):180 mm)和4个施氮水平(N_(0):0,N_(1):150 kg/hm^(2),N_(2):275 kg/hm^(2)和N_(3):400 kg/hm^(2)),采用多元回归和空间分析方法,分析降水条件下灌水施氮对玉米田间耗水、产量、水氮利用效率、硝态氮积累的影响。结果表明:1)随灌水量增加,土壤贮水消耗量占田间耗水量比例减小,W_(1)水平下,N_(1)处理土壤贮水消耗量占比较N_(0)处理提高16.99%,施氮有利于提高玉米对土壤水的利用能力;2)产量随灌水量和施氮量增加呈先增后减的趋势,W_(1)处理产量较W_(0)处理提高18.89%,N_(1)处理产量较N_(0)处理提高29.54%,W_(1)N_(1)处理在获得高产的同时提高水氮利用效率;3)灌水和施氮会促进土壤硝态氮积累和垂向运移,增加硝态氮淋失风险;4)灌水81~102 mm、施氮143~161 kg/hm^(2)时,玉米产量和水氮利用效率达到最优值的95%以上,且硝态氮积累量较低。本研究发现,在枯水年降水条件下,研究区灌水81~102 mm、施氮143~161 kg/hm^(2)可满足玉米生长,实现保障产量、提高水氮利用效率和降低环境污染风险的优化目标。

[Background]North China is the main production area of summer maize,but there are problems with insufficient water resources and excessive application of nitrogen fertilizer in this area,which not only reduces water and nitrogen use efficiency,but also leads to the accumulation of soil nitrate nitrogen and increases the risk of environmental pollution.There are relatively few researches on determining the optimization goals of water and nitrogen management based on maize yield,resource utilization efficiency and environmental effects.This paper explored the irrigation and nitrogen levels that can meet the multiple goals of maize under precipitation conditions.[Methods]A two-factor completely random combination was used for field experiments at the irrigation experimental station in Tongzhou district,Beijing from June to October 2019.The experiment set 4 irrigation levels(W0:0,W1:60 mm,W2:120 mm,and W3:180 mm)and 4 nitrogen application levels(N0:0,N1:150 kg/hm^(2),N2:275 kg/hm^(2),and N3:400 kg/hm^(2)).The field water consumption was calculated based on the water balance,and the soil nitrate nitrogen content was determined through soil sampling and laboratory tests,the effects of irrigation and nitrogen application on maize water consumption,yield,water and nitrogen use efficiency,and nitrate nitrogen accumulation were analyzed,and multiple regression and spatial analysis methods were used to determine the irrigation and nitrogen application for meeting the multiple goals of maize.[Results]1)With the increase of irrigation water,the proportion of soil water storage in water consumption decreased.Under W1 irrigation treatment,the soil water storage ratio of N1 treatment increased by 16.99%compared with N0 treatment.Nitrogen application was beneficial to improve the utilization of soil water.2)The yield increased first and then decreased with the increase of irrigation and nitrogen application.The yield of W1 treatment increased by 18.89%compared with W0 treatment,the yield of N1 treatment increased by 29.54%compared with N0 treatment.W1N1 treatment improved water use efficiency and nitrogen partial factor productivity while obtaining high yield.3)The accumulation of 0-100 cm soil nitrate nitrogen increased significantly with the increase of nitrogen application rate.Increasing irrigation promoted the downward migration of nitrate nitrogen.W1 treatment significantly reduced the risk of nitrate nitrogen leaching.4)Yield,water and nitrogen use efficiency reached more than 95%of their optimal values simultaneously when the irrigation amount was 81-102 mm and the nitrogen application was 143-161 kg/hm^(2),and nitrate nitrogen accumulation was low.[Conclusions]Therefore,irrigation of 81-102 mm and nitrogen application of 143-161 kg/hm^(2)in North China under the conditions of precipitation in dry years may meet the growth of maize,achieve the optimization goal of ensuring yield,improving water and nitrogen use efficiency and reducing environmental pollution risks.The research may provide theoretical reference and technical support for the reasonable and effective development of agricultural water and soil resources and sustainable agricultural development in North China.