Spatial variability of bulk density and soil water in a small catchment of the Loess Plateau

Topography and land use types are key factors which affect soil properties variability on catchment scale in the loess hilly area.Spatial variation of bulk density and soil water were analyzed according to different land use types and different landscape positions,based on data from 82 points in Zhujiagou catchment in Hengshan county.Correlation analyses were carried out between bulk density,soil water and terrain attributes.Finally,terrain attributes and land use types were used to predict bulk density and soil water spatial distribution by multiple-linear regression analysis.There is little difference in bulk density among different land use types,but there is a tendency: shrub landgrasslandterrace farmlandcheck-dam farmlandwoodlandslope farmland.For soil water content,that the tendency is: check-dam farmlandgrasslandshrub landslope farmlandwoodlandterrace farmland.The bulk density series for bulk density according to landscape position is: crestflatlower slopeupper slopemiddle slope.For soil water content the positions order is: flatmiddle slopelower slopeupper slopecrest.Correlation analyses were carried out between bulk density,soil water and terrain indices.It was found that there is positive correlation between bulk density and compound topographic index(CTI);There is a strong negative correlation between soil water and elevation,and a positive correlation between soil water and profile curvature(Kv).The regression model is precise for the soil bulk density,but the variation is rather large and there is a more smoothing effect on the predicted values for soil water.