中文摘要：

【目的】对等高草篱的功能与效益进行长期监测和综合分析,为北方地区坡耕地水土流失和农业面源污染防治提供理论依据和预防措施。【方法】以径流小区为基本手段、以狼尾草（Pennisetum alopecuroides（Linn.）Spreng）为代表,布设草篱处理和无草篱作为对照,其后对两种处理下土壤的物理性状、水分条件、养分水平、水土流失、养分流失以及作物产量等进行连续5年的观测,通过对比分析揭示等高草篱的各种功能,同时对其成本和作物产量效应进行综合分析。【结果】（1）狼尾草是北方地区优良的草篱候选草种,该草篱可显著改善土壤物理性质,种植5年可使土壤容重降低7.0%、稳定入渗率和总孔隙度分别增加157.1%和11.0%,并使土壤细颗粒含量（〈0.01 mm）增加10.8%;（2）草篱可显著改善土壤水分条件和肥力水平,使表层土壤含水量平均增加3.5%,同时使土壤有机质及全量养分和速效养分含量明显增加,其中有机质和速效磷增幅最大,分别为12.7%和24.5%;（3）草篱年均可减少63.2%的地表径流和77.7%的土壤流失,同时减少69.4%的总氮、72.7%的硝态氮、57.3%的铵态氮、54.2%的全磷和62.3%的可溶性磷流失,具有显著的水土流失和农业面源污染防治效果;（4）草篱对其附近作物的增产作用为21.5%,但由于草篱本身需占用耕地,因此作物总产量略有降低;（5）狼尾草草篱的应用成本为2 701元/公顷,与坡改梯等工程措施相比优势明显。【结论】狼尾草草篱价格低廉、效果显著,是防治坡耕地水土流失和农业面源污染的有效措施,可在中国北方地区普遍推广。

英文摘要：

【Objective】 The functions of contour grass hedges on sloping croplands were studied,and its cost benefits were analyzed in this research.It is hoped that the results could provide solutions for the serious problems of soil and water loss and agricultural non-point source pollution on sloping croplands in Northern China.【Method】 The plots with Pennisetum alopecuroide（Pennisetum alopecuroides（Linn.） Spreng） grass hedges and no grass hedges were established.Then the relative parameters,including soil physical properties,soil water and nutrient content,loss of soil and water and soil nutrient,and crop yield,were continuously measured for the plots with grass hedges and no hedges during the period of 2006 to 2010.Finally,the effectiveness of the grass hedges was concluded from the comparative results of the treatments with grass hedges and no hedges.In addition,the cost benefit analysis of grass hedges was also conducted through its costs and effects on crop yield.【Result】 The soil physical properties were significantly improved by the grass hedges.In the research,the soil bulk density was decreased by 7.0%,and the stable infiltration rate,total soil porosity,soil fine particles（0.01 mm） and surface soil water content were increased by 157.1%,11.0%,10.8% and 3.5%,respectively,by the grass hedges after 5 years.The soil nutrient content was also greatly increased by the grass hedges,especially for organic matter（12.7%） and available phosphate（24.5%）.The grass hedges averagely decreased runoff by 63.2%,soil loss by 77.7%,total nitrogen by 69.4%,nitrate nitrogen by 72.7%,ammonium nitrogen by 57.3%,total phosphate by 54.2% and available phosphate by 62.3%.The grass hedges increased the yield of the crop near the hedges by 21.5%.However,the total crop yield of the plots with grass hedges was slightly decreased because that the grass hedges took up some land area which was originally available for crops.The cost of the grass hedges in this study was 2813 RMB per hectare,which is much cheaper t