Land use effects on soil properties in a hilly area, northern China

The rational use of land in the hilly areas of China has become an urgent task for the Chinese government. This study was undertaken to evaluate the effects of different land uses on soil bulk density and soil nutrients in the hilly areas of Zunhua, northern China. Samples were collected from the surface soil (0-20 cm) of pine forest, grassland, chestnut forest, and farmland that had been cultivated for 6 months and for over 3 years, respectively. The results indicated that deforestation and cultivation increased soil bulk density and decreased most soil nutrients. Compared to pine forest, the bulk density value of grassland, 6 months cultivated land, chestnut forest and 3 years cultivated land increased by 13.3%, 14.2%, 27.5%, and 39.7%, respectively. Soil nutrients except available N and P showed significant differences among different land uses. Compared to pine forest, soil nutrient contents except total P in chestnut forest and 3 years cultivated soils decreased significantly. Chestnut forest decreased soil organic matter (SOM) by 60.7%, total N by 35.6%, total K by 21.3%, and available K by 57%; while 3 years cultivated soils decreased SOM by 62.9%, total N by 52.6%, total K by 31%, and available K by 60%. The deterioration indices showed that a severe degradation occurred to 3 years cultivated land and to chestnut forest. Cultivation on steeper slopes (>20degrees) should be prohibited. Because the soils in chestnut forest did not deteriorate as severely as slope farmland, and because chestnut forest can produce more economic benefits, it can be selected to be a rational land use in the hilly area of Zunhua County. However, soils under chestnut forest will severely deteriorate unless appropriate soil and water conservation practices are used.