Effects Of Slow-release Nitrogen Fertilizer Application Ratio On Winter Wheat Yield,water And Nitrogen Use Efficiency

Wheat is the second largest grain crop in China,and in search of high yield,unreasonable overapplication of nitrogen fertilizer during wheat cultivation in Guanzhong,Shaanxi Province,has led to poor nitrogen fertilizer use efficiency and increased pollution.Therefore,this study chose the method of slow-release nitrogen fertilizer with urea application,and field trials were conducted in Yangling,Shaanxi Province,in which seven treatments were set up with no nitrogen fertilizer N0,and 100% urea N1 and four different slow-release nitrogen fertilizer application treatments: N2(100%),N3(25%),N4(50%),and N5(75%),with no fertilizer application as the control.The main studies were conducted to investigate the effects of different dosing treatments on growth status and dry matter,yield and constituents,nitratenitrogen content and distribution,nitrogen uptake and water-nitrogen use efficiency of winter wheat soils,and to find solutions to the problem of inefficient nitrogen fertilizer use during wheat cultivation in Guanzhong,Shaanxi Province.The main findings of the study are as follows:(1)Application of slow-release fertilizer with urea was able to reduce the accumulation of nitrate-nitrogen in the soil from 0～100 cm at maturity,while increasing the proportion of nitratenitrogen content in the soil from 0～40 cm at the surface.The nitrate-nitrogen content of all wheat treatments showed a trend of increasing and then decreasing in depth,and the maximum nitrate-nitrogen content of slow-release fertilizer treatments was at 20 cm and concentrated in the 0～40 cm soil layer,where the accumulation of nitrate-nitrogen in the surface layer of 0～40cm was the largest in N5 treatment,which was 1.30%～19.52% higher than that in N1～N4treatment,and the nitrate-nitrogen content in N2 treatment was 37.80% higher than that in N1 treatment was 37.80% higher.The slow-release nitrogen fertilizer was applied with urea at 3:1,and the largest percentage of nitrate-nitrogen residue was in the surface layer from 0～40 cm,and the least amount of nitrate-nitrogen residue was in 0～100 cm.(2)The application of slow-release fertilizer with urea promoted the increase of plant height,leaf area index and chlorophyll content in winter wheat at mid and late reproductive stages,with the greatest in N5 treatment.Slow-release nitrogen fertilizer with urea significantly increased the accumulation of dry matter and nitrogen uptake in wheat at maturity compared with slow-release nitrogen fertilizer and urea alone.At maturity,the N5 treatment had the highest aboveground dry matter mass,which increased by 9.20% and 11.40% compared to N1 and N2 treatments,respectively;the N5 treatment also had the highest nitrogen uptake,which increased by 11.49% and 24.08% compared to N1 and N2 treatments,respectively.The aboveground dry matter mass and nitrogen uptake of winter wheat at maturity showed N5>N4>N3>N2>N1>N0>CK.(3)The application of slow-release fertilizer with urea could significantly improve the yield and water and nitrogen use efficiency of winter wheat.The highest yield and water and nitrogen use efficiency was found in N5 treatment.57.26% yield increase was found in N5 treatment compared with N1 treatment,and 22.41% yield increase was found in N5 treatment compared with N2 treatment.22.42% water use efficiency was increased in N5 treatment compared with N1 treatment;10.10% water use efficiency was increased in N5 treatment compared with N2 treatment.agronomic utilization rate were increased by 22.41%,101.04%,and 79.44%,respectively;meanwhile,they were increased by 11.24%,69.60%,and 23.50%,respectively,compared with the N2 treatment.Both yield and water and nitrogen utilization efficiency showed a trend of increasing and then decreasing with the increase of slow-release fertilizer application rate.The yield and water N use efficiency showed that N5>N4>N3>N2>N1>N0>CK.According to the curve fitting data,there was better water and nitrogen use efficiency at 55%～62% application rate.Considering the yield,nitrate nitrogen residue and water nitrogen utilization efficiency,the treatment of slow-release nitrogen fertilizer with urea at 3:1(N5)was the best nitrogen fertilizer application ratio for fertilizer saving and efficiency production of winter wheat under the conditions of this experiment,which can be used as a reference indicator for wheat fertilization pattern in Guanzhong area,and the fertilizer application ratio of 55%～62% can be used as the next research scope.