Effect of Nitrogen Application on Winter Wheat Yields and Nitrate Nitrogen Accumulation in Soils of Surrounding Farmland in Baiyangdian Lake

[Objective]The aim was to research the effect of nitrogen application on winter wheat yields and in soils of surrounding farmland inBaiyangdian lake.[Method]The field experiment was carried out to study the effects of nitrogen application on yields of winter wheat,efficiencyof nitrogen fertilizer and nitrate nitrogen accumulation in soils of two representative agricultural fields.[Result]The results showed that the opti-mum amount of nitrogen could improve the wheat grain number,grain weight and other yield components and efficiency of nitrogen fertilizersignificantly.The nitrate nitrogen mainly existed in 0 ～ 30 cm soil layer and their concentrations increased with the increases of nitrogen appli-cation levels.The accumulations of soil nitrate nitrogen decreased in 0 ～ 90 cm depth with the growth period passed.In mature stage,the accu-mulations rapidly increased the increases of nitrogen application levels when the nitrogen application rate was higher than the optimum amountof nitrogen.So the higher nitrogen application increased the risk of nitrate nitrogen transportation from soil surface layer to the deep layer.[Conclusion]Considering the yield and environmental benefits,the optimum amounts of nitrogen were 225 kg/hm2 in MaPu and 90 kg/hm2 inZhangLiu fields respectively under the experimental conditions.