膜孔灌灌施尿素条件下氮素转化和分布室内模拟试验

Laboratory simulation experiment on nitrogen transformation and distribution under condition of film hole irrigation with urea solution

为了提高膜孔灌氮肥利用率,减少氮肥损失,通过室内膜孔灌灌施尿素模拟试验,研究了膜孔灌灌施尿素条件下氮素转化和分布规律,结果表明:灌施600mg/L尿素溶液后,转化生成的铵态氮主要分布在膜孔中心附近,随着距离膜孔中心的增大而减小,0～5d时铵态氮含量逐渐增大,5d后逐渐减小。在7d前,硝化作用微弱,上层土壤硝态氮含量低于本底值,7d后,硝化作用增强,上层土壤硝态氮含量明显增大,远高于本底值,且水平方向转化生成的硝态氮含量大于垂直方向。在尿素转化过程中,铵态氮减少量远大于硝态氮增加量,表明尿素转化过程中氮素损失较大。以上成果为进一步研究膜孔灌灌溉施肥技术提供了参考。

For improving the use efficiency of nitrogen fertilizer and decreasing the losses of nitrogen fertilizer,the rules of nitrogen transformation and distribution under film hole irrigation with urea solution were studied through laboratory simulation experiment.The results showed that the ammonium nitrogen mainly distributed around film hole and decreased with the increasing of distance from film hole.The ammonium nitrogen content increased gradually in the early 0-5 d and decreased subsequently after the fifth day.The nitrification was weak before the seventh day and the nitrate nitrogen content in the top soil layer was lower than background value.The nitrification was enhanced after the seventh day.The nitrate nitrogen content in the top soil layer was more than background value;the nitrate nitrogen content in the horizontal direction was more than in the vertical direction after the seventh day.During the course of urea transformation,the decrement of ammonium nitrogen was far more than the increment of nitrate nitrogen.The research results provide reference for further study of film hole irrigation and fertilizer application.