Effects of Nitrogen Fertilizer Application Rate on Nitrogen Absorption,Translocation and Nitrate Nitrogen Content in Soil of Dryland Wheat

【Objective】The objective of this experiment was to study the effects of nitrogen fertilizer application rate on the nitrogen utilization regulation in Yellow and Huaihe River valleys,and to provide a scientific basis for rational nitrogen application in this area.【Method】The experiment was conducted to determine the effects of nitrogen fertilizer application rate on nitrogen absorption,translocation and nitrate nitrogen content in soil of dryland wheat by using six nitrogen levels of 0(control),90 kg.hm-2,120 kg.hm-2,150 kg.hm-2,180 kg.hm-2,and 210 kg.hm-2,respectively,under field conditions in 2009-2010 and 2010-2011 wheat growing seasons.【Result】 The results showed that nitrogen accumulation amount at various growth stages,nitrogen accumulation amount in grain at maturity,N translocation amount from absorbed N before anthesis to grain and nitrogen absorption amount after anthesis were significantly increased as nitrogen fertilizer application rate was lower than 150 kg.hm-2.As nitrogen fertilizer application rate was increased based on 150 kg.hm-2,nitrogen accumulation amount at various growth stages,N translocation amount from absorbed N before anthesis to grain and nitrogen absorption amount after anthesis had no significant difference with those of nitrogen fertilizer application rate 150 kg.hm-2,nitrogen accumulation amount in grain and its ratio were decreased whereas nitrogen accumulation amount in vegetative organs and its ratio were increased.When nitrogen fertilizer application rate was increased to 180 kg.hm-2 and 210 kg.hm-2,the nitrate nitrogen contents in 0-140 cm soil layers at maturity were significantly higher than those of 150 kg.hm-2,and the nitrate nitrogen content at deeper soil layers were also increased.Nitrogen fertilizer application rate of 150 kg.hm-2 treatment gained the highest grain yield,as well as relatively high nitrogen use efficiency and nitrogen productive efficiency.【Conclusion】N application at 150 kg.hm-2was considered to be optimum under the experimental conditions.