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农田养分的大量流失已成为农业非点源污染的主要来源之一,针对施肥后降雨作用下农田沟渠氮素迁移规律的研究对农业非点源污染的防治具有重要意义。由于水稻生育后期施肥量大大减少,故以宜兴市何家浜上游的水稻耕作区为研究对象,重点对比分析了施肥后降雨作用下水稻生长前期沟渠水的氮素浓度分布特征,以及降雨径流过程中沟渠氮素的迁移规律。研究结果表明:(1)降雨量≤15 mm的限制型降雨事件中,处于施肥中期、末期的沟渠系统整个降雨过程中TN浓度波动范围较小;(2)水稻生长前期沟渠系统氮素输出的主要形态为NH4+-N和NO3--N,且降雨初期径流以颗粒态氮为主;(3)沟渠对氮素具有截留效应,沿沟渠水流方向氮素含量总体上沿程下降。
The heavy loss of farmland nutrients has become one of the main sources of agricultural non-point source pollution. The research on the nitrogen migration rules of farmland ditches under the rainfall after fertilization is of great significance to the prevention and control of agricultural non-point source pollution. Due to the greatly reduced amount of fertilization in the late rice growth stage, the rice cultivation area in the upper reaches of Hejiabang in Yixing City was taken as the research object. The distribution characteristics of nitrogen concentration in the ditch water during early rice growth after fertilization were comparatively analyzed, and the rainfall runoff process Nitrogen transport in canals. The results show that: (1) During the limited rainfall events with rainfalls ≤15 mm, the fluctuation range of TN concentration during the whole rainfall of ditch system in the middle and end of fertilization is small; (2) The main forms are NH4 + -N and NO3 - N, and the runoff is dominated by particulate nitrogen at the beginning of rainfall. (3) The ditches have a retention effect on nitrogen, and the nitrogen content along the ditch water flow generally decreases along the route.