The Effects Of Land Use Type On Red Soil Quality

Red soil hilly area is an important base of economic forest and fruit,food,fishery and animal husbandry production in tropical and subtropical areas of China,which occupies an important position in the development of national economy.However,due to the uneven spatial and temporal distribution of precipitation,high temperature and humidity and other natural conditions,coupled with excessive development and utilization,inadequate soil and water conservation measures and other human factors,leading to serious degradation of red soil quality.Among them,land use and management measures are the most common,direct and profound factors affecting the quality of red soil.In this study,the red soil with different land use types and changes in land use type is taken as the research object.Through field investigation,sampling and laboratory analysis to understand the effects of different land use and land use change on the physical-chemical properties of red soil,and to clarify the interaction of land use,texture and slope position on the properties of red soil,and then to comprehensively evaluate the quality of red soil.The main results obtained in this paper are as follows:(1)Land use type and land use change significantly affect the structural and moisture characteristics,p H,total and rapidly available nutrients,available trace elements content of red soil,and their effects will vary with the changes of soil texture,slope position and soil depth.(2)The red soil in the study area was mainly composed of macroaggregates,and the clay content was relatively high,which was basically more than 30%.The p H,organic matter and total nitrogen content of soil decreased with the depth of soil layer in different land use types.The differences of SM,CMC and FC in Quaternary red soil and argillaceous shale red soil between land use types were all smaller in the U-S than that in the M-S and L-S,and their trends were similar.(3)After forest reclamation,the contents of macroaggregate,sand,water holding capacity,organic matter,total nitrogen,available iron and available copper decreased significantly,while the contents of microaggregate,<0.053 mm aggregate,nitrate,available phosphorus and available potassium increased significantly.Forest reclamation can reduce the content of soil total nutrients and improve the availability of rapidly available nutrients.(4)Soil saturated water conductivity(Ks)and the content of nitrate(NO3-),total phosphorus contents(TP),organic matter(SOM),available potassium(AP),ammonium(NH4+),available potassium(AK),available iron(A-Fe),available manganese(A-Mn),available copper(A-Cu)and available zinc(A-Zn)can be used as main indexes to evaluate the impact of land use type on red soil quality.In the study area,except for the farmland of argillaceous shale red soil(middle level),the quality of other sample lands is at a low level.The physical and chemical properties of red soil were significantly affected by land use type,and the effects varied with the changes of slope position and soil texture.The red soil quality in the study area is generally at a low level.In the future management practice,measures should be taken such as increasing the content of organic matter,supplementing phosphate fertilizer and preventing red soil erosion to improve red soil quality.