施肥与植被覆盖对坡地铵态氮流失的影响

Effect of fertilization and vegetation coverage on ammonium nitrogen runoff in slope soil

【目的】明确黄土高原地区施用氮肥及不同植被覆盖对坡地土壤NH4+-N流失的影响。【方法】在人工模拟降雨条件下,利用室内可调节坡度的铁皮冲刷槽,研究降雨径流过程中坡面NH4+-N流失特征,以及坡度、植被覆盖、施用氮素肥料对坡面表层土壤NH4+-N流失的影响。【结果】施用到土壤中的NH4+-N会随径流流失,且主要随着泥沙流失而流失,极少部分NH4+-N入渗到土壤深层;施用NH4NO3会增加土壤自身的NH4+-N流失;植被覆盖减少了坡面土壤自身NH4+-N随泥沙流失的数量,但是加剧了添加氮肥中随径流流失的NH4+-N的数量。【结论】在坡地施用氮肥和种植植被,都会加剧坡地土壤自身中的NH4+-N流失,从而对生态环境产生危害。

[Objective]This research studied and clarified the influential effects of different nitrogen fertilizers and vegetation coverage on NH4＋-N runoff in slope soil over Loess Plateau. [Method]Under the conditions of simulated rain- fall, experiments were conducted with gradient-adjusted sheet scour tanks to study the NH4＋-N runoff character on slope soil and the impacts of slope gradient, vegetation coverage, and foreigner nitrogen fertilizer on NH4＋-N runoff in slope soil. [Result ]NH4＋-N concentration decreased with surface runoff after NH4＋-N application in soil; the NH4＋-N concentration mainly lessened with sediment losses with only few NH~＋-N infiltration into the soil. Application of NH4N03 could increase the NH4＊-N loss in soil. Vegetation coverage reduced the NH4＋-N loss with sediment runoff but increased the NH4＋-N loss with added-nitrogen water runoff. [Conclusion ]The application of nitrogen fertilizer or plant vegetation will aggravate the NH4＋-N loss on soil slope, which was harmful to the local ecological environment.