The Soil Physical Characteristics in the Small Watershed of Diediegou Located on the North Side of Liupan Mountains

Based on field investigations,the variation of soil physical characteristics with soil depth,slope aspect,slope position,and vegetation types within the small watershed Diediegou located on the north side of Liupan Mountains,Ningxia,China was studied.The result shows:(1) The soil density and stone content increased with increasing soil depth;while total porosity,capillary porosity,non-capillary porosity,saturated water content,(capillary) soil water content,and field capacity of soil decreased with increasing soil depth.But the non-capillary porosity increased with soil depth in the range of deeper than 100 cm,since the stone content was getting higher in deeper soil layer.(2) All the soil physical properties measured in this study were basically better on the south slope than on the north slope and all other half-sunny slopes.There was very less difference between south slope and all other half-sunny slopes in term of research soil physical properties.(3) With lowering slope position,the soil thickness,soil density,stone content,and non-capillary porosity were gradually increasing;while the total porosity,capillary porosity,and all water-holding capacity indicators gradually decreasing,with an exception that the water-holding capacity on the up-slope was higher that on the slope top.(4) By comparing the averaged soil physical properties of upper soil layer(0~30 cm) among four main vegetation types,the soil density in abandoned farmland was the highest,the woodland the second,the grassland the third,and the shrub land the lowest.The stone content of soil in the abandoned farmland was the least,and there was less difference among all others land types.For the total porosity,capillary porosity,saturated soil water content,capillary soil water content,and field capacity,their order from high to low was shrub land,grassland,woodland,and abandoned farmland.For the non-capillary porosity,its order from high to low was abandoned farmland,woodland,shrub land,and grassland.Finally,the regression(equations) between the researched soil physical properties and altitude,soil aspect,slope gradient,slope position,soil depth,and ground vegetation coverage were established.