Analysis on Soil Bulk Density of Small Karst Watershed under Different Land Use Patterns

With the karst watershed of Xiaxiaozhai in Bijie district as the research unit,influences of gravel content and land use patterns on soil bulk density were analyzed. The reaults showed that the gravel content was negatively related to total soil bulk density and bulk density of fine earth significantly. The orders of total bulk density or bulk density of fine earth were not same in different soil layers from surface to 100 cm depth.Total bulk densities and bulk densities of fine earth in different soil layers in woodland were significantly different from vegetable plot,cornfield and artificial grassland. There was no significant difference in total bulk densities and bulk densities of fine earth in different soil layers of woodland and returned land. These meant that soil physical feature might be improved by reducing disturbances and leaving farmlands lay fallow.