Response of winter wheat to different nitrogen managements in North Central China

The field experiments were conducted to investigate the effects of different nitrogen（N） fertilizer rates and the ratio of basal N and topdressing N on winter wheat growth, grain yield and the change of soil N content in Hengshui and Xinji, Hebei province, respectively. The results show that indigenous N supply could meet the demand of N for winter wheat normal growth before the revival stage, and the applied N fertilizer do not significantly increase wheat grain yield in Hengshui site, while compared with the treatments of applying basal N and topdressing N, the applications of topdressing N only at shooting and booting stages at the ratio of 2:1 increase N use efficiency significantly. In Xinji site, 60 kg N /ha could meet the demand of N for wheat growth before the shooting stage, all N are applied as topdressing at the shooting stage do not eliminate the effect of N deficient at the early growth stage on wheat growth and high grain yield, and the application of 240 kg N/ha at the ratio of 1:3 (basal N and topdressing N ) at the shooting stage could achieve higher grain yield and N use efficiency compared with other treatments. The apparent N loss during winter wheat growth season mainly comes from the basal N, while high topdressing N rates at mid-later stages also increase soil N residual after the harvest. Because of the variations of soil fertility and texture, the effects of the same N management method on winter wheat growth, yield and N use efficiency in two sites are different, so for higher crop yield and higher N use efficiency, the synchronizing regulation of N fertilizer should combine crop nutrient demand, nutrient supply from soil and regional variation characters of soil fertility and texture.