中文摘要：

研究北京粮食作物种植区冬小麦-夏玉米轮作体系下不同施氮量对土壤氮素剖面分布、累积量、淋失量的动态变化过程的影响及对地下水的影响等。结果表明在喷灌条件下冬小麦试验季节硝态氮的累积主要在80cm深度以上；而夏玉米季节，硝态氮的峰值运移到150cm左右，硝态氮存在明显的深层淋失现象。硝态氮的剖面含量一般随着施氮量的增加而增加。单季施氮量低于110kg／hm2，土壤氮素处于稍微亏损状态；而施氮量大于220kg／hm2时，在0～200cm土层内，硝态氮有明显的累积现象，硝态氮的累积量一般随着施氮量的增加而增加，因此建议该地区年施氮量为250kg／hm2以维持农田氮平衡。考虑到当地的地下水埋深一般在12．5m左右。可以初步得出冬小麦一夏玉米种植对地下水的影响较小，但是长期冬小麦一夏玉米种植施肥将对地下水产生影响。

英文摘要：

In this paper, the effects of different amount of nitrogen fertilizer application on nitrate distribution and accumulation in soil profile, and their effects on groundwater environment have been studied in winter wheat- summer maize rotation system in Beijing area. Results showed that most of nitrate accumulated in 0- 80 cm soil profile, the peak of nitrate content occurred at around 50 em soil depth in winter wheat season when sprinkling irrigation system was used. However in summer maize season, the peak of nitrate content has moved to 150 em soil depth, causing an obvious nitrate leaching. Nitrate content in soil srofile increased with the increasing of nitrogen fertilizer application. Nitrogen application per crop season of less than 110 kg/hm2 causeed N defeit in root zone, while application amount of higher than 220kg/hm2 resulted in great N accumulation in 0-200 cm soil profile. The N accumulation amount generally increased with increasing rate of nitrogen applicalton, Baseu on the soil nitrogen balance, a seasonal N application of 250 kg/hm2 was recommended in the studied region under wheat/corn rotation system. Considering the groundwater level was around 12.5 m in this region it could be concluded that the effect of winter wheat-summer maize system may do minor effect on groundwater environment at present, while more attention should be payed to their long-term effect.