Distribution of Soil Properties as Affected by Landforms in Small Watershed of Loessial Gully Region
黄土高原沟壑区小流域不同地形下土壤性质分布特征

Landform is the most important environmental factor influencing soil properties of the Loess Plateau.The well understanding of the effects of landforms on the distribution of soil properties is an important prerequisite for the estimation of soil quality of the Loess Plateau.This study was therefore conducted in a small watershed of the loessial gully region to reveal the profile distribution of soil properties as affected by landforms.Soil samples distributed into various landforms were collected and soil properties were determined.The results showed that nitrate,available phosphorus,alk-phosphatase and invertase are highly varied properties while soil pH and catalase are lowly varied properties in the study area.Soils of plateau land and gully bottom were characterized by the lower pH and catalase activity but higher cation exchange capacity.The contents of organic matter,total nitrogen,total and available phosphorus and the activities of alk-phosphatase and invertase were decreased gradually with the increase of soil depth in profile.Besides,these properties followed the order of plateau land>terrace land>slopping land>gully bottom.Changes in soil pH at different landforms were caused by the soil-forming processes and the accumulation of nitrate in soils.The differences of soil cation exchange capacity with landforms were derived from the differences in soil formation,soil pH and organic matter.The variance of soil nutrients was led by the landuse conditions corresponded to landforms,while that of enzymatic activities was led by landform induced changes of soil organic matter.