横坡垄作壤中流条件下垄高对径流态氮磷流失的影响

Effects of Ridge Height on Losses of Nitrogen and Phosphorus in Runoff under Seepage Condition for Contour Ridge System

以棕壤横垄为研究对象,基于人工模拟降雨,研究壤中流条件下垄高(8,12,16cm)对不同侵蚀阶段(壤中流、壤中流+降雨沟间侵蚀和细沟侵蚀)径流态氮、磷流失的影响。结果表明:(1)壤中流侵蚀阶段,NO3-N、NH4-N和PO4-P的浓度和流失量均表现为垄高16cm>8cm>12cm;壤中流+降雨沟间侵蚀和细沟侵蚀阶段,养分浓度表现为垄高8cm>16cm>12cm,流失量为垄高8cm>12cm>16cm。12cm是有效控制氮、磷流失的最佳垄高。(2)壤中流侵蚀和沟间侵蚀阶段,随垄高增加养分流失的变化幅度逐渐增大,而细沟侵蚀阶段则呈平稳趋势。(3)壤中流侵蚀和沟间侵蚀阶段垄高的变化并未引起氮、磷流失机制的改变,而细沟侵蚀阶段垄高的变化改变了氮、磷流失机制。(4)垄高对氮流失的影响高于对磷的作用强度。

A laboratory rainfall simulator study was conducted to determine effects of ridge height（8,12,16cm）on nitrogen and phosphorus losses in runoff for brown soil under different erosion stages（seepage erosion,interrill erosion and rill erosion for seepage with rainfall）.Results showed that：（1）Under seepage stage,NO3-N,NH4-N and PO4-P concentrations and losses under different ridge heights were in order：16cm〉8cm〉12cm,under stages of interrill and rill erosion for seepage with rainfall,nutrient concentrations were ranked in the following order：8cm〉16cm〉12cm and nutrient losses in the sequence of 8cm〉12cm〉16cm.This indicated ridge height of 12 cm was determined to be most suitable for controlling nutrient losses under seepage condition.（2）Along with the increase of ridge height,variation ratio of nutrient losses gradually increased under stages of seepage and interrill erosion,while for rill erosion stage,it presented steady tendency.（3）The variation of ridge height changed nutrient losses mechanism under rill erosion stage,while under stages of seepage and interrill erosion it unaltered mechanism of nutrient losses.（4）The influence degree of ridge height on nitrogen loss was greater than on phosphorus loss.