Abstract: 【Objective】 The fate and residual effect of fertilizer nitrogen under winter wheat-summer maize rotation were studied using filed 15N microplot in north China. 【Method】 In the field 15N-micropolt experiments, nitrogen applied at 0, 75, 150, 225, 300 kgN•hm-2 (N0, N75, N150, N225, N300) and two wheat varieties were used under winter wheat-summer maize rotation in North China Plain.【Result】The results showed that all the late three crops could utilize the 15N-labeled residual from the first winter wheat. Along with 15N-labeled fertilizer application rates increasing, the 15N was up-taken by the after three crops increased significantly, but following the increasing of crops for rotation, the absorption amounts and absorption rate decreased significantly. Overlying N utilization efficiency of four crops was significantly higher than the N utilization efficiency of the right winter wheat. The overlying N utilization efficiency in N75, N150, N225 and N300 treatments accounted for 53.8%, 58.7%, 58.6% and 55.8% when HN822 was the first crop and 60.0%, 61.3%, 60.9% and 55.2%, respectively, when KN9204 was the first crop. After the fourth summer maize harvest, the range of soil residue in profile was 22.3-96.2 kgN•hm-2, the ratio of soil residue was from 22.1% to 32.8%. The range of total loss was 9.3-55.3 kgN•hm-2, and the loss ratio was 8.9% to 18.6%. 【Conclusion】 Two rotation systems finished. There was residual 15N in 0-200 cm soil profile after two crops rotation. With the nitrogen fertilizer application rates increasing, the nitrate and residual 15N amount increased. With the increasing of crops growth, the moving trend of nitrate and residual 15N was downward in vertical direction.

Key words: winter wheat, summer maize, fate of nitrogen, N residual effect, 15N