The apparent surplus and deficiency of soil N in winter wheat-summer maize rotation were investigated under different N application rates (N0

N100

N180

N255

N330) in consecutive six years in Qingyuan

Hebei. Results showed that the cumulative apparent nitrogen balances changed from the deficit in N0 and N100 treatments to the surplus in N180

N255 and N330 treatments

which reached up to 382

1 173 and 2 116 kg/hm2

respectively. The large annual variations of the apparent N balances were found

but the differences of the N balances between the two crops were small

which were 155 kg/hm2 and 134 kg/hm2

respectively. Meanwhile

it was observed that the apparent soil N balances were negatively correlated with the changes of soil inorganic N and the precipitation

but positively correlated with N application rates. In addition

the apparent soil N surplus in the earlier stage and deficit in the later stage during the growing seasons of winter wheat and summer maize were observed. These findings above indicated that reasonable N recommendation should be established from two aspects including soil apparent N balance and N allocation within a growing season.