为了揭示农田灌溉过程中N素流失的原因以及对水环境的污染，以内蒙河套灌区北场试验区为研究对象，在田间试验结果分析的基础上，研究了秋浇退水前后农田排水N素流失的影响因子及其规律，分析了N素流失的过程。试验结果表明，灌水量、沟渠分布，地形地貌是农田N素流失的主要影响因素；N素流失对地表水与地下水环境造成一定影响；得出了其在地上、地下水环境中的迁移规律：秋浇后沟道水中TN、NH3-N浓度明显增大，沟道周围地下水TN浓度变沿退水方向逐渐增大。初步估算出试验区的NH3-N流失量、NH3-N残留量与输出量比例关系为6:1。

Abstract：In order to reveal the reason of Nitrogen lost in the agriculture irrigation process and the pollution to water environment,we take the BeiChang test area as the research object in Inner Mongolia HeTao irrigation area and based on the analysis of the field result, the impact factor and the law of Nitrogen lost in agriculture drainage in pre and post autumn irrigation recession was studied.,analysed the process of Nitrogen lost. The results show that the irrigation amount 、distribution of fitch and topography and geomorphology are the main impact factors of Nitrogen lost in agiculture. The Nitrogen lost will cause effectson surface water and groundwater. This paper obtain its migration law in surface and groundwater environment : total Nitrogen, ammoniacal Nitrogenconcentrations increased after autumn irrigation,totalnitrogenconcentration s increased gradually around the channel groundwater along the back water. Preliminary estimated the relation was 6:1 about Nitrogen lost amout 、subsurface filtration amount and surface lateral seepage in experiment.