Water retention and supply for four types of vegetation in Gangcha County were analyzed through the determination of soil physical properties and soil water characteristic curve.Results indicate that soil water characteristic curves for four types of vegetation are well in accordance with Van Genuchten model and the values of R2 are greater than 0.99

which indicate that Van Genuchten model may exactly describe the relationship between quantity and energy of soil moisture.The contents of physical clay are in the decreasing order of rape landtall grass landgrass and bush land;soil bulk densities

tall grass landgrass and bush landrape land;and soil total porosities

rape landgrass and bush landtall grass land.The result shows that soil physical properties for rape land are better than those for other two lands.Soil water retention increases with the increased soil suction and presents a trend of abrupt decrease in first stage to gentle change in latter stage.Soil water retentions for different vegetation types are in the decreasing order of tall grass landgrass and bush landrape land.Soil water retention can be effectively enhanced with the practices that improve soil physical properties by improving soil structure

increasing soil bulk density and reducing soil total porosity.Soil water supply decreases gradually with increased soil suction.Soil water supply at low soil suction for dense grass and bush land and tall grass land is obviously better than that for rape land and thin grass and bush land

while soil water supply at high soil suction for dense grass and bush land and rape land is obviously better than that for tall grass land and thin grass and bush land.These show that the vegetation on tall grass land and thin grass and bush land is easily threatened by drought.