Based on N application rates and soil tillage modes experiment, yield of spring maize and NO3 - N accumulation in soil profile were studied in the northwest of Hebei Province. The results showed that compared with conventional tillage, no-tillage mode had no significant effect on yield of spring maize, through analyzing function curve of N rate and yield of spring maize under no-tillage 1, no-tillage 2 and conventional tillage modes, and the proper rate of N of spring maize was 192 ～ 209 kg/hm2, 192 ~ 212 kg/hm2 and 196 ～ 216 kg/hm2 respectively. With the increase of N rate, NO3 - N accumulation in 0 ～ 90 cm and 90～80 soil layers were also significantly increased by three treatments.NO3 - N accumulation in 0 ～ 90 cm soil layer under no-tillage mode was higher than that under conventional tillage in whole sampling period, and this trend increased with increase of N application rate. After maize was harveste d, NO3 N accumulation in 0 ～ 90 cm soil layer under no-tillage mode was significantly higher than that under conventional tillage mode, while NO3 - N accumulation in 90～ 180 cm soil layer under conventional tillage mode was significantly higher than that under no-tillage mode, this indicated that more N nutrient accumulated in 0 ～ 90 cm soil layer under no-tillage mode and less leached into groundwater for environment pollution.%在冀西北春玉米种植区,对不同施氮量和耕作方武春玉米产量和土体硝态氮累积状况进行研究分析,结果表明,和常规耕作相比,免耕对春玉米产量无明显影响,通过建立的施氮量和春玉米产量的肥料效应函数,求得免耕1(玉米和大豆间作)、免耕2(玉米单作)和常规耕作(玉米单作)3种处理的适宜氮推荐用量分别为192～209 kg/hm2、192～212 kg/hm2和196～216 kg/hm2.随着施氮量的增加,3种处理0～90 cm土层和90～180 cm土层的硝态氮累积量均呈显著增加趋势.在春玉米整个取样期,免耕处理0～90 cm土层硝态氮累积量均高于常规耕作处理的累积量,而且这种趋势在高施氮量下表现得更明显,春玉米收获后,免耕处理0～90 cm土层硝态氮累积量显著高于常规耕作的累积量,而常规耕作处理90～180 cm土层硝态氮累积量显著高干免耕处理的累积量,这说明免耕措施更有助于硝态氮累积在0～90 cm土层,而减少向下淋失进入地下水,产生环境污染的可能.
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