Effects Of Nitrogen Redution And Different Coverage On Winter Wheat Yield,water And Nitrogen Use And Root Distribution

Water and nutrient were two factors that affect crop yield to ensure sustainable development.From the perspective of resource utilization and sustainable development,water conservation cultivation measures of dryland are the direction of winter wheat agriculture development in the north.In this study,the winter wheat in Yongshou County of Shaanxi Province was taken as the research object.Continuous field trials were conducted for 4 years,to no nitrogen fertilizer for the blank,nitrogen application 195 kg / hm2 as a control,facilities nitrogen 150 kg / hm2 farmers nitrogen reduction,ridge mulching and furrow sowing,film mulching and hole sowing,and straw mulching and hole sowing,a total of 6 treatments.The effects of different mulching cultivation on winter wheat yield,soil water use efficiency,nitrogen use efficiency,and root growth of winter wheat were discussed.The main results are:1.After reducing the amount of N applied from 195 kg / hm2 to 150 kg / hm2,compared with no cover treatment,Using the ridge mulching and furrow sowing technology did not increase wheat yield,but increased the aboveground N uptake,thereby increasing the N requirement of grain yield,reducing the physiological efficiency of nitrogen;Using the film mulching and hole sowing technology to increase the grain yield,while increasing aboveground N uptake,but did not increase the N requirement of grain yield and the N physiological efficiency of grain yield;Using the straw mulching and hole sowing technology to increase the grain yield,while increasing aboveground N uptake and the N requirement of grain yield,Thereby reducing the N physiological efficiency of grain yield.2.Under the amount of N application rate of 150kg/hm2,compared with no cover treatment,the physiological efficiency of ridge mulching and furrow sowing increased by 12% in the year 1,water consumption increased significantly by 7% in the year 2,improve the physiological efficiency of nitrogen fertilizer and water consumption;The yield,sowing water storage capacity and N physiological efficiency of film mulching and hole sowing was significantly increased by 15%,15% and 16% in the year 1,in the second year were significantly increased by 12%,10% and 35%;The yield,sowing water storage capacity of straw mulching and hole sowing was significantly increased by 9% and 16%,water use efficiency and aboveground nitrogen uptake in the second year were significantly increased by 12% and 17%;There was no significant effect of nitrogen reduction on farmer's winter wheat yield and water use.Therefore,nitrogen reduction and coverage measures was an important measure to realize the effect of increasing yield and efficiency of winter wheat in dryland.3.The different coverage of winter wheat also affects the content of NO3--N and its distribution.Compared with no cover treatment,The NO3--N residues in film mulching and hole sowing decreased by 78%,92% and 69% in 2013 ~ 2014 and 2014 ~ 2015 two flat water years and 2015 ~ 2016 years of poor years;Straw mulching and hole sowing reduced by 26%,66% and 68% in 2012 ~ 2013 and 2015 ~ 2016 two years of poor water and 2013 ~ 2014 years of water.Compared with 4-year average content of NO3--N of nitrogen reduce,ridge mulching and furrow sowing,film mulching and straw mulching and straw mulching and hole sowing were significantly reduced by 39%,55% and 32%.With the passage of the year,the accumulation of NO3--N in soil gradually decreased,and the peak was shifted down.4.Under different cover treatment,with the increase in soil depth,root system indicators were a downward trend.In 0-20 cm soil layer,the surface area density and bulk density of the roots are significantly reduced.Total root length of ridge mulching and furrow sowing and film mulching and hole sowing were significantly reduced by 35%,26% in the year 1,total root dry weight,total root length of straw mulching and hole sowing were significantly reduced by 63%,43% in the year 1,reduced by 41% and 17% in the year 2.The total root dry weight and total root length of winter wheat were significantly decreased by ridge mulching and furrow sowing,film mulching and hole sowing and straw mulching and hole sowing.After covering the surface,soil temperature changes,the film is heated and the straw is cooled,thus inhibiting the growth of winter wheat root system.Root growth were related to different growth stages of winter wheat,this study was only measured data of flowering period,so the relevant research to be further carried out.