植物篱对紫色土区坡耕地水土流失及土壤肥力的影响

植物篱的水土保持效果已得到广泛的认可，并在世界很多地方推广应用，然而，到目前为止，植物篱对坡耕地土壤肥力的影响规律研究却很少。利用长期定位小区试验，研究了植物篱对坡耕地土壤肥力的影响规律，旨在弄清植物篱提高土壤肥力的作用与效果，不断完善植物篱技术。研究发现，坡耕地在建立植物篱后，土壤粘粒在篱前富积，篱下加剧侵蚀，粘粒的富积与侵蚀沿等高线成水平带状分布;土壤有机质、N、P等主要营养元素出现与土壤颗粒相同的分布规律;对K来说，其分布不受植物篱的影响，表现出较为均一分布的特点。从土壤养分的绝对数量来看，P呈高度富积，而有机质和K则是高度耗竭。因此，坡耕地施肥时可以适当减少P的施用量，增加有机物和K的施用量。针对植物篱带对坡耕地肥力影响的特点，即篱前肥力升高，篱下肥力下降，在坡耕地管理上应特别加强篱下土壤带的培肥，以提高坡面整体生产能力。

The effects of plant hedgerows on soil erosion and soil fertility on sloping farmland in the purple soil area

Effect of using plant hedgerows to control soil and water losses has received wide recognition and this technology has been applied in many areas in the world. Yet, studies on its effect on soil fertility of sloping lands are rare. Using an eight-year fixed field experiment, the authors investigated the effect of two different hedgerows against the control treatment on soil fertility. Results showed that clay particles tended to accumulate above the plant hedgerows and to be eroded downward below the hedgerows along contour lines across the field. Distribution of soil organic matter and all plant nutrients except K showed the same pattern as the clay particles. Potassium (K), however, was evenly distributed in the field without any noticeable influence from the hedgerows. Since the fixed experiment started, soil P has kept accumulating, while soil organic matter and K are in depletion. The results suggest accordingly better nutrient management practices on the sloping lands by using reduced rates of P and increased rates of farm manure and K. Taking the sloping field as a whole, special attention in nutrient management should be given to the soil stripes the portions below the plant hedgerows suffering from more serious soil erosion.