Effect of maize straw applied with N fertilizer on nitrogen adsorption of winter wheat under different soil fertility

By adopting the doubly-labeled method of 15N-labeled urea and 15N-labeled maize straw, pot experiments were carried out to study the effect of maize straw direct return on winter wheats N accumulation, nitrogen distribution and nitrogen fertilizer recovery in 2 soils with different fertility. These results indicate that under the condition of same N fertilizer application amount, the nitrogen accumulation of winter wheat is decreased with the return of maize straw compared with non maize straw return, while the nitrogen harvest index is increased with the return of maize straw since nitrogen accumulation is decreased more significantly in winter wheats stalk than that in its kernel. The nitrogen content of winter wheat seed cultivated in the high fertility soil is higher than that in the low fertility soil, while the nitrogen content of winter wheat straw cultivated in the high fertility soil is lower than that in the low fertility soil. The nitrogen recovery rates are declined by 9.6%-15.7% and nitrogen residual rates are increased by 12.2%-16.4% under the nitrogen fertilization applied with maize straw return. About 22.8%-33.1% nitrogen accumulation of winter wheat and 7%-10% nitrogen accumulation of winter wheat seed are from the returned maize straw when the N-fertilizer application rates are N 150 and 300 kg/ha. Under the condition of the same N fertilizer application rate and the same soil fertility, the impact of N fertilizer applied with maize straw on the seed yield of winter wheat is not significant, and the effect of soil fertility on the use efficiency of maize straw nitrogen is larger than that of the nitrogen fertilizer. This result should be proved by further field experiment.