Abstract:

【Objective】For quantitatively studying the characteristics of nitrogen (N) fertilizer utilization and the fate of fertilizer N in summer maize, an experiment was conducted in Wuqiao Experimental Station of China Agricultural University in 2005. 【Method】The experiment design was employed with four N fertilizer application rates (0, 90, 180, 270 kgN·hm-2) and three replications in each treatment, and was carried out by the techniques of soil column and 15N-label under the condition of artificial weather shed. 【Result】Application of N fertilizer significantly improved the dry matter, grain yield, total N uptake rate of maize plant and grain. There was no significant difference in PNUE (physiological N fertilizer use efficiency) but showed a tendency of rising firstly and falling then with the increase of N fertilizer applied. AENF (agronomic efficiency of applied N-fertilizer) and ANRE (apparent N fertilizer recovery efficiency) decreased significantly with the increase of N fertilizer applied. The recovery ratio of 15N was 41.2%-47.8% in maize season and the percentage of residual 15N in 2 m-depth soil body was 40.7%-47.5%. Residual 15N rates of different soil layers increased significantly with the increase of N fertilizer applied (P＜0.05) and decreased obviously with the add of soil layer depth. Loss rates of 15N increased significantly with the increase of N fertilizer applied and total 15N loss ratio was 9.0%-13.1%. 【Conclusion】Proper rates of N applied（90-180 kg·hm-2）would be favorable to improve grain yield and N use efficiency, reduce residual 15N rates in soil body (especially in deep-soil layer) and therefore lighten the environment pressure.