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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80 cm深度以上;而夏玉米季节,硝态氮的峰值运移到150 cm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110 kg/hm2,土壤氮素处于稍微亏损状态;而施氮量大于220 kg/hm2时,在0～200 cm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—夏玉米种植对地下水的影响较小,但是长期冬小麦—夏玉米种植施肥将对地下水产生影响。
This paper studied the effects of different amount of nitrogen application on dynamic changes of soil nitrogen profile distribution, accumulation and leaching loss under the winter wheat-summer maize rotation system and its effect on groundwater in Beijing food crop growing areas. The results showed that nitrate accumulation in winter wheat was mainly above 80 cm in sprinkler irrigation season. In summer maize season, the peak value of nitrate nitrogen shifted to about 150 cm, and significant nitrate leaching was observed. The profile of nitrate nitrogen generally increases with the increase of nitrogen application. Nitrogen was less than 110 kg / hm2 in a single season, and the soil nitrogen was in a slightly depleted condition. When the nitrogen application was more than 220 kg / hm2, nitrate nitrogen accumulated obviously in 0 ~ 200 cm soil layer. The nitrogen accumulation generally increases with the increase of nitrogen application rate, so it is recommended that the annual nitrogen application rate is 250 kg / hm2 in order to maintain the nitrogen balance of the farmland. Considering that the local groundwater depth is generally about 12.5m, it can be concluded that the effect of winter wheat-summer maize planting on groundwater is small, but the long-term winter wheat-summer maize planting and fertilization will have an impact on groundwater.