黄土高原水土流失严重地区土壤抗冲性的水平和垂直变化规律研究

Study on Horizontal and vertical Regulation of Soil Anti-scourability in Area with Serious Soil Erosion on Loess Plateau

采用原状土冲刷水槽装置，对吕梁山以西，长城沿线以南，渭河以北，和甘肃黄河以东的１０６县（市）、旗范围内的土壤抗冲性进行了野外测试，结果表明，本区土壤抗冲性存在自北至南和自西北至东南逐渐递增的趋势；在沿土壤剖面深度垂直变化上，存在三种迥然不同的形态，即：（１）作物根系活动层（１０～３０ｃｍ）土壤抗冲性较大，表层及根系活动层以下抗冲性很弱的农业耕作影响型；（２）粘化层土壤抗冲性大，两侧甚小的土壤成土过程影响型；（３）表层土壤抗冲性最大，往下越来越小的生物生长影响型。前两种土壤抗冲性沿剖面垂直变化曲线类似正态分布曲线，第三种则类似双曲线。根据测试结果，还将研究范围内的土壤抗冲性划分成五个区域。

Soil anti-scourability(SAS)in 106 counties(cities)from west of luliang mountain,southof Great Wall,north of weihe and east of Yellow River in gansu province were tested in the field.The result showed that SAS in this area was increased from north to south and morthwest to south-east :on the profile of soil,SAS had three types :1).Cultivation determination type with strong SASin crop root layer(10～30cm),and low SAS in the surface roil and below crop root layer. 2).Soilformation determination type,which had greater SAS in argillic horizon than that of other layers.3).Plant growth determination type,SAS decreased from top to bottom of soil profile. The regula-tion of SAS in the profile of soil in former two types is similar with normal destribution curve,andthe latter is similar with hyperbola. Based on the analysis,the SAS can be divided into five areas inresearch region.