中文摘要：

以土垫旱耕人为土为供试土壤，通过田间试验，研究了不同施氮量下（0、45、90、135和180kg·hm^-2）夏玉米生育期土壤剖面NO3^--N的变化特征、氮素利用率及施氮量与土壤NO3^--N残留的关系．结果表明：在整个生育期内，土壤NO3^--N含量均以0～20cm土层最高，且施氮量越高，NO3^--N含量也越高；0～60cm土层NO3^--N含量变化显著，60～100cm土层NO3^--N含量变化不大．夏玉米整个生育期，受玉米对氮素的需求和降雨的影响，0～100cm土层NO3^--N累积量呈波动式降低趋势；当施氮量小于135kg·hm^-2时，作物氮肥利用率随施氮量的增加而显著提高，但当施氮量超过135kg·hm^-2时呈下降趋势．氮肥农学利用率随施氮量的增加而减小，氮肥生理利用率随施氮量的增加而递增．土壤中残留NO3^--N与施氮量呈极显著正线性相关关系（R^2=0．957^＊＊，n=5）；施氮处理籽粒产量显著高于不施氮处理（P〈0．05）；施氮量与籽粒产量呈极显著正线性相关关系（R^2=0．934^＊＊，n=5）．在本试验条件下，夏玉米生长季适宜施氮量为135kg·hm^-2．该施氮水平可保证效益和环境的双赢．

英文摘要：

A field experiment on manual loessial soil was conducted to study the dynamic changes of NO3^--N in soil profile, utilization rate of fertilizer N, and relationships between N application rate and soil residual N accumulation during the growth period of summer maize under different N application rates （0, 45, 90, 135, and 180 kg·hm^-2）. The results showed that in the whole growth period of summer maize, the NO3^- -N concentration in the soil profile was the highest in 0-20 cm layer, and increased with increasing N application rate. The NO3^--N concentration in 0-60 cm soil layer changed significantly, but no significant change was observed in 60-100 cm soil layer. In the growth season of summer maize, soil NO3^- -N accumulation presented a fluctuated decreasing trend due to the N uptake by crop and the precipitation. The N utilization rate （NUR） increased with increasing N application rate when the application rate was less than 135 kg·hm^-2, but tended to decrease when the application rate exceeded 135 kg·hm^-2. With the increase of N application rate, the N agronomy efficiency （NAE） decreased but the N physiology efficiency （NPE） increased. There was a significant positive correlation between soil residual N accumulation and N application rate （R^2 =0. 957 ^＊ ＊ , n = 5 ）. The grain yield under N application was significantly higher than that without N application （P 〈 0.05 ）, and there existed a significant positive correlation between grain yield and N application rate （R^2 = 0. 934^＊ ＊ , n = 5 ）. In our experiment, the optimal application rate of fertilizer N was 135 kg·hm^-2, which could harmonize the relationship between economic benefits and environment.