Effect of Nitrogen Application Rate on Nitrate Nitrogen Distribution and Accumulation in Soils in Wheat-Maize Rotation System

The 6 year-field experiment was carried out to study the effects of nitrogen application rate on soil nitrate nitrogen distribution,accumulation and crop yield in wheat-maize rotation system.The results showed that the suitable amount of nitrogen fertilizer application of the winter wheat should be about 250 kg/ha to guarantee high yield at piedmont plain of Hebei province.The suitable amount of nitrogen fertilizer application of the corn should be about N 150 kg/ha.From the effect of nitrogen application rate on soil nitrate nitrogen distribution and accumulation,the nitrogen application rate for lower than 150 kg/ha could basically control soil nitrate nitrogen leaching loss to deep soil,which can reduce groundwater pollution risk caused by soil nitrate nitrogen leaching.From the effect of nitrogen application rate on crop partial productivity,with the increasing of nitrogen amount,the partial productivity of wheat and corn decreased obviously.For the treatment of N 150 kg/ha,the partial productivity of wheat and maize were maximum for 43.09% and 56.76% respectively.Considering the effect of nitrogen fertilizer rate on crop yield and soil nitrate leaching risk,nitrogen fertilizer rate for wheat and corn should not exceed 150 kg/ha at piedmont plain of Hebei province.