摘要
等高植物篱带间距选择是坡地植物篱－农作系统的表土养分流失控制的重要一环。通过对植物篱带间养分流失的发展过程分析，认为在带间径流侵蚀处于溅蚀分散－片流搬运为主的阶段时，篱前淤积层宽度应使水流流速衰减至小于一定粒径的土壤细颗粒的起动流速，才能有效减少养分流失。通过推导的一些公式估算，在三峡库区秭归县的植物篱试验区，带间距相当于细沟侵蚀发生的临界坡长（６ｍ）时，天然降雨条件下片流侵蚀仍不足以侵蚀携带＜０．０２ｍｍ的土壤颗粒。因此，细沟侵蚀是决定此类地区土壤细粒物质侵蚀的关键因素。从控制带间表土流失出发，等高植物篱带间距应控制在细沟侵蚀发生的临界坡长以内。
The design of suitable distance between contour hedgerows
is important factor for controlling the nutrient loss and nonpoint pollution in the hedgerowcrop
system on slopeland. According to this goal, the width of the trapped sediment in front of
hedgerows should be enough to make the flow as slow as the threshold of initial move velocity
for the fine particles in certain diameter. Calculations by the deduced equations indicated under
natural rainfall condition, the sheet flow can not move the <0.02 mm particles even at the
distance of 6 m at which the rill erosion probably can generate at the studied plots in the Three
Gorge Reservoir region. According to controlling the nutrient loss in the studied region, the
critical length of rill erosion generation isthe crucial factor of design of suitable distance
between contour hedgerows.
基金
国家自然科学基金
国务院三峡工程建设委员会移民开发局资助
