Effects of Maize Yield and N Application on N Utilization and Content of Soil Nitrate

Field experiment was carried out to investigate N application on yield,soil nitrate accumulation,plant N uptake and utilization of two kinds of maize.The results showed that maize yield increased significantly with the increment of nitrate application rate,but the biomass of maize decreased and the yield of grain of maize didn't increase when the nitrogen application rate was higher than 200 kg/ha.Nitrogen application significantly increased nitrate content in all layers of soil profile and hyper-accumulation of nitrate was found in 0-100 cm soil layer in the treatment of 200 kg/ha nitrogen application.There were differences in the yield and plant total amount of N absorption among 2 types of maize.Total amount of N absorption and the content of soil nitrate in the high dose treatment which planted density-tolerance maize Xianyu 335 were higher than density no-tolerance maize Liaodan 28.High nitrogen using efficiency was found in the treatment whose nitrogen fertilizer rate was 200 kg/ha.Under the experimental conditions,with the consideration of yield,nitrogen utilization and soil nitrate accumulation,a reasonable amount of nitrogen application should be controlled at about N 200 kg/ha.