Effects of Land Use on Soil Quality in a Hilly Area ——A Case Study in Zunhua County of Hebei Province

How to use rationally the lands in hilly areas is very important to preserve soil quality and develop sustainable land use model. This study was undertaken to evaluate the effects of land use on soil nutrients and soil bulk density in the hilly area of Zunhua County of Hebei Province. Samples were collected from top soil (0～20 cm) of pine forest, grassland, chestnut forest, and slope farmland that had been cultivated for about 6 months and for over 3 years. The results indicated that deforestation and cultivation led to increase in soil bulk density and decrease mostly in soil nutrients. Compared to pine forest, the bulk density value of grassland, 6 months's cultivated land, chestnuts and 3 years cultivated land increased by 13.3%, 14.2%, 27.5% and 39.7%, respectively. Most soil nutrients except available N and available P showed significant differences among different land use types. Soil nutrient contents except total P in chestnuts and over 3 years cultivated soils decreased significantly in comparison with pine forest. Chestnut forest witnessed a decrease in soil organic matter by 60.7%, total N by 35.6%, total K by 21.3% and available K by 57%; while over 3 years cultivated soils saw a decrease in SOM by 62.9%, total N by 52.6%, total K by 31% and available K by 60%. The soil degradation indices showed that grassland and slope farmland cultivated for about 6 months did not degrade significantly, however, a severe degradation occurred to over 3 years's cultivated land and chestnut forest. Obviously, cultivation on steeper slopes results in severe soil degradation and diminishes greatly soil quality. It seems that the development of chestnuts by deforestation is also not a sustainable land use model though more income can be obtained. The soils under chestnuts will subject to severe degradation unless appropriate soil and water conservation practices were conducted.