Effects Of Land Use Changes On Soil Quality In Ecological Immigration Zone Of Guangxi

The ecological migration leads to dramatic changes in land use in the migrationarea. Such land use changes may alter the soil quality in various ways. This studyaims to quantify the effects of different land-uses, i.e., nature forest, grassland,secondary shrub, eucalyptus forest, corn field and cane field, on soil properties andsubconsequent soil quality in an ecological migration zone in Guangxi ZhuangAutonimous Region via space for time, field sampling and laboratory analysis in2013.The results have important impilications for land-use planning and land sustainablemanagement in ecological migration zones. The results show that:1.Land use changes driven by ecological migration profound impact on the soilnutrients and soil quality. The average soil organic carbon content were between8.84~12.9g/kg in the0~100cm soil layer. Soil organic carbon content decreased by10.9~29.2%from natural forest to other types,and it decreased by20.4%~31.4%from grassland to other types.With soil depth, soil organic carbon content decreased indifferent land use types, which were an exponential relationship.2.Soil total nitrogen content were between0.8~1.2g/kg in the different land usetypes. Soil total nitrogen content decreased by19.4%~38.8%from natural forest toother types,and it decreased by27.8%~45.2%from grassland to other types.Theaverage soil total phosphorus content were between0.8~1.2g/kg. Soil totalphosphorus content were most in corn field,while it were lest in eucalyptus forest,Soil total phosphorus content were not significantly different (P>0.05) between landuse types.3.Soil microbial carbon content decreased with soil depth in different land usetypes. Soil microbial carbon content were between50~210mg/kg in the differentland use types. And its tend was nature forest>secondary shrub>grassland>eucalyptus forest>cane field>corn field. Soil microbial carbon content decreased by43.19%~74.59%from natural forest to other types,and it decreased by12.36%~48.23%from grassland to other types. Soil microbial nitrogen content is between8~39mg/kgin different land use types in the0~100cm soil layer. And its tend was nature forest> grassland>secondary shrub> eucalyptus forest>cane field>corn field. Soil microbialnitrogen content decreased by46.81%~77.41%from natural forest to other types.Itdecreased by31.34%~65.37%from grassland to other types.4.The soil organic carbon, total nitrogen, ammonia nitrogen, nitrate, microbialcarbon and microbial nitrogen were selected as appraisal factors in the study.Andsoil comprehensive score method and Markov were used to calculate the soill qualitychange. The soill quality decresed from nature forest to other types. The effect wasmost significant from nature forest to cane field and corn field.