Effects Of Water And Nitrogen Treatments On Water And Fertilizer Use Efficiency And Root Distribution Of Wheat In Supplementary Irrigation Area Of Central Henan

Irrational irrigation and excessive fertilization in wheat production not only seriously wastes water and fertilizer resources,reduces water and fertilizer utilization efficiency,but also brings adverse effects on farmland ecological environment.In order to explore the effects of water and nitrogen treatment on water and fertilizer utilization efficiency and root distribution of wheat in supplementary irrigation area of central Henan.In this study,irrigation(150 mm)and no irrigation(rainfed)at jointing stage,conventional N(225 kg·hm-2)and incremental N(330kg·hm-2)were used as treatments,and Zhoumai 27,Luomai 28 and Luohan 6 were used as materials for field water and fertilizer experiments.Root chamber simulation experiment of Zhoumai 27 and Luomai 28 with 370 mm(sufficient irrigation)and 270mm(water saving irrigation)irrigation was conducted.By analyzing the effects of water and fertilizer treatment on wheat growth and development,dry matter accumulation,grain yield,water and fertilizer utilization,soil nutrients and wheat root morphology distribution,this study aims to provide a theoretical basis for wheat water and fertilizer collaborative management according to regional characteristics,realize the efficient utilization of wheat water and fertilizer and other resources,and promote the green and sustainable development of wheat production.The main findings are as follows:(1)The differences in aboveground dry matter mass,plant nitrogen,phosphorus and potassium accumulation and yield of wheat were not significant for the rainfed treatment compared with the irrigated treatment at the same N application rate,but the rainfed treatment significantly increased the water use efficiency of wheat,and water use efficiency of wheat respectively reached 22.23~25.55 kg·mm-1·hm-2 and 15.29~17.78 kg·mm-1·hm-2.(2)Under the same moisture condition,330 kg N·hm-2 increased the aboveground dry matter,plant N,P and K accumulation and yield of wheat compared to 225 kg N·hm-2,but the difference was not significant.Nitrogen fertilizer use efficiency was significantly lower at 330 kg N·hm-2,while phosphorus and potassium fertilizer use efficiency and water use efficiency were not significantly different.(3)Total nitrogen,phosphorus and potassium in the soil were mainly distributed in the 0~40 cm soil layer,and the content of total nitrogen and phosphorus in the 40~100cm soil layer tended to be stable,while the content of total potassium in the 80~100 cm soil layer was also higher.Nitrate nitrogen was mainly distributed in the 0~40 cm soil layer at the nodulation stage,moved with soil moisture,and increased in the 60~100cm soil layer at maturity.Ammonium nitrogen was mainly distributed in the 0~20 cm soil layer at the nodulation stage,and basically did not move with water,and the ammonium nitrogen content of each soil layer did not differ greatly at the maturity stage.The available phosphorus was mainly distributed in the 0~20 cm soil layer at the nodulation stage and moved with moisture,and increased in the 20~40 cm soil layer at the maturity stage,and stabilized in the 40~100 cm soil layer.Rapidly available potassium tended to decrease and then increase as the soil layer deepened,with higher levels in both the 0~20 cm and 80~100 cm layers.Loss of nitrate nitrogen,available phosphorus and available potassium in soil was reduced by conventional nitrogen application in rainfed;increasing nitrogen fertilizer application under rainfed condition increased the residual nitrate nitrogen in soil.(4)Soil nitrate nitrogen in root chamber increased first and then decreased with soil depth,mainly distributed in 40~60 cm soil layer.Soil ammonium nitrogen first increased and then decreased with soil depth,mainly distributed in 20~40 cm soil layer.Soil available phosphorus increased first and then decreased with soil depth.The peak of soil available phosphorus was in 20~40 cm soil layer from jointing stage to 16 days after flowering,and the peak of soil available phosphorus was in 40~60 cm soil layer at maturity.The mature period of soil available potassium is mainly distributed in60~100 cm soil layer.Compared with water-saving treatment,sufficient irrigation increased the leaching of nitrate nitrogen,available phosphorus and available potassium in soil.(5)Sufficient irrigation was conducive to increasing root length,root surface area,root volume and root tip number of roots in 0~40 cm soil layer;Water saving was beneficial to increase root length,root surface area,root volume and root tip number in 40~100 cm soil layer.In summary,in the supplementary irrigation area in central Henan,water-saving and fertilizer-reducing can promote the deep development of root system and the absorption of soil nutrients,so as to achieve stable yield of wheat,improve resource utilization efficiency,and provide theoretical basis and technical support for the green and sustainable development of wheat.