本试验中,使冬小麦和夏玉米氮收获指数和氮素效率出现下降的氮水平临界点分别为225kg/hm~2、150kg/hm~2。

• In the test , the critical point of nitrogen level causing the harvest index and efficiency of nitrogen of winter wheat and summer com to descend appears respectively as 225kg/hm2 and 150kg/hm2.