The field experimentation was carried out at Qianzhuliu village, Beima town of Longkou in shandong provice from Octomber 2002 to June 2003.The experimentation was studied by using two different winter wheat cultivars, jiami20, which has 9000kg/hm2 yield potential and approximately 14% protein content, and yannong15, which has 8500kg/hm2 yield potential and approximately 15% protein content. Field culture method and 15N microplot method were used to study the effect of different nitrogen rate and different r...