不同植被过滤带对农田径流中泥沙和氮磷的拦截效果与途径

在我国农业面源污染已经成为水环境质量恶化和湖泊富营养化的重要原因,其中氮磷对地表水富营养化的贡献超过了50%。通过浑水冲刷试验,研究了3种禾本科植被过滤带((黑麦草Lolium perenne Linn.)、偃麦草((京草2号)Elytrigia repens(L.)Nevski)、无芒雀麦(Bromus inermis Leyss.)对径流、泥沙以及氮磷的拦截效果,同时分析了3种植被过滤带拦截氮磷的主要途径。结果表明:(1)与裸地相比,3种植被过滤带均能显著提高径流与氮磷的拦截率。3种植被过滤带之间对径流、氮磷拦截率没有显著差异。黑麦草过滤带泥沙流失量显著低于无芒雀麦过滤带;同时径流、泥沙与氮磷拦截率之间存在显著正相关关系,表明植被对径流和泥沙的拦截一定程度上决定对氮磷的拦截量;(2)径流过程中磷的流失量均低于氮的流失量。氮的流失主要以溶解态氮为主,占总氮流失量的90%以上;磷的流失则主要以颗粒态磷为主;(3)植被过滤带拦截氮磷的途径不同,氮主要通过增加土壤入渗的途径来拦截,磷则主要通过植物茎秆基部进行物理拦截;(4)京草2号对氮的拦截效果优于黑麦草和无芒雀麦,而黑麦草则在磷的拦截方面表现突出。因此在植被过滤带的优化设计方面可以考虑黑麦草与京草2号2者混播以达到最佳的拦截吸附效果。

Interception Ways and Effects of Grass Filter Strips on Sediment, Nitrogen and Phosphorus in Agricultural Runoff

In China,agricultural non-point source pollution has become an important reason for water environmental deterioration and lake eutrophication,with the contribution of nitrogen and phosphorus to the eutrophication of surface water being more than 50 ％.This study was conducted to evaluate the effects of herbaceous grass filter strips established by perennial ryegrass (Lolium perenne Linn),Jingcao No.2 (Elytrigia repens (L.) Nevski) and smooth bromegrass (Bromus inermis Leyss.) on the interception of runoff,sediment,nitrogen,and phosphorus in a simulated experiment in soil boxes with runoff generators.The results showed that:(1) The runoff,nitrogen,and phosphorus loss on the plot were significantly reduced by the three types grass filter strips.The sediment loss of ryegrass filter strip was significantly less than that of Jincao No.2 and smooth bromegrass.The result of correlation analysis showed that the nitrogen,phosphorus interception rate was significantly correlated with the runoff,and sediment interception rate.(2) The loss of phosphorus in four kinds of treatments were lower than that of nitrogen,with more than 90％ of nitrogen being lost in dissolved nitrogen,and phosphorus being mainly lost in particulate phosphorus.(3) Nitrogen was mainly intercepted by soil infiltration,and phosphorus was mainly intercepted by plant stem.(4) The nitrogen loss of Jingcao No.2 filter strip was less than that of ryegrass and smooth bromegrass filter strip,and the phosphorus loss of ryegrass filter strip was less than that of Jingcao No.2 and smooth bromegrass filter strip.Therefore,in order to improve the interception of nitrogen and phosphorus,ryegrass and Jingcao No.2 can be planted in a mixing way when building the herbaceous filter strips.