Abstract: Fifty-six 1 m² samples land (volume moisture of soil 7. 1%～20%, dry unit weight of 1.19～1.29 g/cm³) was selected on the sloping land in Nihegou Valley of Chunhua County in southern part of loess plateau. Using "WI-3" type Straightforward Shear Instrument made in Soil Instrument of Nanjing, 0～5 cm topsoil samples are sheared. The results of shearing showed that shear strength of topsoil was closely related to moisture and unit weight. At the initial stage, shear strength increased slowly with increasing of moisture of soil. It was maximal when the moisture was 12%～14% and then it decreased rapidly. With increasing of soil unit weight, strength of soil increased rapidly in trend of straight line. Through the experiment of sloping land of rainfall erosion in laboratory (areas of sloping land is 0.3×1.0 m 2, intensity of rainfall is 1.39, 1.49, 1.88 and 2.62 mm/min respectively), amounts of soil of splashing and scouring erosion collected showed that whether splashing erosion or scouring erosion, ant-i erosion capability is maximal when dry unit weight of soil (1.2 g/m³) was similar and moisture of soil is 16%. Therefore, considering influement of unit weight, shear strength as ant-i erosion index is reasonable. Original topsoil collected from farm land, wasteland and bush land were watered and set on scouring groove (volume 1 m×0.062 m×0.06 m). They were scoured at same time range and under the condition of 15°slope degree and 5 L/min water flow). Difference of scouring modulus soil sample weights before and after scouring divided by water flow was by contracting and analyzing clay content, dispersion coefficient, dispersion rate and organic matter. It was found that ratio of clay content of micro-aggregate and of machanical composition was closely related to scouring in unit water volume. Ant-i erosion capability of soil increased with increasing of dispersion rate. So, dispersion rate can use as indicate for ant-i erosion.

Key words: Soil erosion, an-ierosion capability, index