Abstract: To better understand the optional N application of summer maize,field experiment with the summer maize-winter wheat rotation was carried out in Huang-huai-hai Plain in 2002-2003.Four rates of nitrogen fertilizer(i.e.0,90,180,270 and 360kg/ha) were applied to maize with high-yield hybrid Zhengdan 958 and the population of 9 plants per square meter.The following crop is winter wheat with cultivar 97-3 and seed rate of 704 grain per square meter.N rate of 144kg/ha was applied at wheat sowing.With exception of the precipitation of 112.1 mm during wheat season,two times of irrigation with 75 mm at each time were used on April 13 and May 9,2003,respectively.The influences of maize N rates on soil inorganic N dynamics during wheat season and wheat N utilization were examined.The results are as follows:In comparison with zero N applied to maize(ZN),N applied to maize significantly increases the content of 0-200cM soil nitrate during wheat season.The nitrate contents in the 0-40,0-130 and 0-200cM soil profiles all apparently ascend with N rate increment from wheat shooting to maturity.The amount of 0-130cM soil inorganic N in ZN plot decreases by 156kg/ha during wheat season.However,that in the N rate of 90kg/ha plot increases by 41kg/ha at the same period,and the amount of soil inorganic N continually increases with the N rate increment during wheat season.At wheat maturity,The amount of plant N and that of grain N both increase with the increment of N rate.The amount of plant N has no significant differences between N rates when N rate is no more than 180kg/ha.There is also no apparent differences of the grain N amount between N rates when N rate is no more than 270kg/ha.In this experiment,the wheat grain NUE is just 0.2%-2.9%.

Key words: Winter wheat (Triticum aestivum L.), N fertilizer rate, Soil inorganic N, N utilization

CLC Number: 

• S512.01