干旱区生态环境知识资源中心

The aim of the present study was to determine the effects of 3 different land-use types (forest land, rural land and pasture land type) and two slope classes (20% and 40%) on soil loss and runoff. A rain gauge was installed in the research area in order to measure precipitation daily, monthly and annually. For each land-use type, two experimental sites (total 6) and 3 plots at each experimental site were taken (6 x 3 = 18 plots totally). A soil profile in each plot was done and undisturbed soil samples were taken from depths of 20 cm using an iron cylinder (10 cm diameter and height). The runoff and sediment measurements were also carried out at each experimental site (totally 324 times). The soil samples were analyzed for soil pH, soil texture, organic matter and permeability.

The results showed that there were significant differences in soil loss and runoff between the three land-use types and each of their two slope classes. Soil loss and runoff for the forest land type were low, compared to the pasture and rural ones. This was mainly due to the tree canopy structure and the blanket of organic matter at the forest floor, which helped to prevent soil loss and runoff from the forest land. The differences in soil loss showed a good correlation with those in soil texture, organic matter and permeability. Soil losses were much higher on the slope of 40% than on that of 20%, both for the pasture and rural lands, indicating that slope classes significantly affect soil losses. The differences in soil losses and runoff between the slope classes can be attributed to the observed high grazing and soil compaction by animals in the studied areas on the slope of 40%.

The soil losses and runoff for the three different land-use types were found to be lower than those in literature. That could be due to the lower precipitation measured (253.7 mm) during the experimental period in the research area. The results were significantly between the three land-use types and their corresponding two slope classes.