Optimum N Application Rate at Different Soil Fertility Levels in Spring Maize

Field experiments were conducted to study the effect of different nitrogen application rates on spring maize in yield,nitrogen utilization and soil nitrate nitrogen accumulation.The results showed that the optimum economic N application rates under economic optimum yields were N 227 kg/hm 2,204 kg/hm 2 and 201 kg/hm 2 for Dongyang,Qixian and Wenshui respectively. When nitrogen application rates increased to a certain value,the yield would no longer increase.The nitrogen use efficiency decreased with the increase of nitrogen application rates,the nitrogen efficiency of N180 and N270 treatment would be higher than the other treatments.The residual nitrate nitrogen in 0-90 cm soil showed as following: the nitrogen application rate higher than 270 kg/hm 2 in Dongyang and 180 kg/hm 2 in Qixian and Wenshui resulted in luxury nitrate accumulation in soils.The research analyzed the effects of different nitrogen application rates on spring maize in yield,nitrogen use efficiency and soil nitrate nitrogen accumulation.It suggested that the nitrogen at the rate of 225 kg/hm 2 could satisfy the maize demand and would not threaten the environment in Dongyang with lower soil fertility,and the nitrogen application rate should be controlled below 200 kg/hm 2 in medium fertility Qixian and high fertility Wenshui.