Characteristics Of Soil Physical And Chemical Properties And Enzymatic Activities Under Different Land Use Types In Northwestern Shanxi

According to the typical land use types in the loess hilly area of Northwestern Shanxi,the experimental plots of Populus simonii Carr.,Robinia pseudoacacia L.,Caragana korshinskii Kom.and abandoned land were selected to study the characteristics of soil physicochemical properties and enzyme activities under different land use types.In June,July,August,September,November,samples of soil samples were collected in the field,and soil moisture,soil bulk density,physical properties of soil particle size,soil organic matter,pH,soil total nitrogen chemical properties and soil enzyme activity were measured in the field(soil alkaline phosphatase,urease,invertase,catalase).After the correlation analysis of soil properties,the response of soil physical and chemical properties and enzyme activity to land use types was clarified,which provided a theoretical basis for ecological restoration and construction of loess hilly region.The results are as follows:(1)The physical properties of soil showed as follows:The soil moisture of four kinds of land use types increased and then decreased with the increase of depth,and the variation of soil moisture content with depth was significant at 0—100 cm soil depth.In the deep layer,the soil water content decreased obviously with the soil depth.And the soil water of the four land-use types all had obvious seasonal variation characteristics.Soil water was affected by precipitation and the depth range of water absorbed by vegetation roots,forming different active layers of soil water.In the soil depth of 0—300 cm,Populus simonii Carr.,Robinia pseudoacacia L.and Caragana korshinskii Kom.were dominated by sand grains,followed by silt;abandoned land mainly dominated by silt,four kinds of land use types with the same soil layer soil bulk density difference is small.(2)Soil enzyme activities were as follows:The alkaline phosphatase,urease,invertase and catalase of the four kinds of land use showed obvious vertical variation,that is,the soil enzyme activity of surface soil was the highest.With the increase of depth,Soil enzyme activity tends to decrease,the deeper the soil,the lower the soil enzyme activity.The activity of alkaline phosphatase in the soil of the Populus simonii Carr.,Robinia pseudoacacia L.and Caragana korshinskii Kom.were significantly higher than abandoned land.The soil urease activity in the Robinia pseudoacacia L.was the highest,while that of the Populus simonii Carr.and Robinia pseudoacacia L.were higher than that in the Caragana korshinskii Kom.and abandoned land.The differences of soil catalase in the four land use types were small.(3)Soil nutrient showed as follows:Soil organic matter mainly concentrated in the soil surface under the four kinds of land use types,and decreased with the increase of soil depth in the vertical section of soil.Compared with abandoned land,the soil organic matter of Populus simonii Carr.was the highest and the gradient of vertical variation was larger.The soil total nitrogen also had more surface layers.In the deep soil layers,the content of soil total nitrogen also be low.From July to September,it increased slightly.Generally speaking,the difference of soil total nitrogen content among the four land use types was obvious.The content of total nitrogen in the soil was significantly higher than abandoned land.(4)The correlation between soil physical and chemical properties and enzymatic activities showed that the correlation between soil organic matter and total nitrogen,alkaline phosphatase,urease,invertase and catalase reached extremely significant level,and soil enzyme activity and organic matter,total nitrogen and other nutrients between the larger,four kinds of soil enzyme activity,soil alkaline phosphatase and urease,sucrase very significant correlation between urease and sucrase,catalase between the extremely significant correlation.There was a significant correlation between invertase and catalase.