The Application Of Meta-analysis On The Land Use Effects On Soil In The Purple Soil Area

Purple Soil is distributed widely in China.It is the main agricultural soil resources and the main production base for citrus and mulberry in our country. Because the purple soil's mother rock is porosity and easily to disintegrate,the contents of Phosphorus and Potassium are rich,as well as the soil fertility is high,it has been already developed and utilized extensively.However the purple soil layer is shallow and its mother rock's physical weathering is strong,it is vulnerable to being washed.Unreasonable land-use makes the purple soil's soil and water loss as well as soil erosion severely.Thus it leads to reducing the soil fertility,making soil thin and exposing the rock under the air.Under these circumstances,it has caused a great deal of environmental damage,and furthermore it has impacted on the development of agriculture and the sustainable use of resources.Land-use is the interaction process between natural and human activities.As a part of the earth surface system,the land's own conditions and human land-use will certainly have an impact on the land at different aspects.Furthermore it impacts the ecosystem and environment that depend on the land.Numerous domestic and international studies have shown that the relationship between the change of physical and chemical properties of soil and the land-use was close.Different land-use patterns can change the soil physical and chemical properties as well as soil biological nature and soil environmental conditions.They are the main factor of soil and water loss. Soil and water loss not only affects the region's ecology,livelihood and production security,but also seriously hampers the sustainable development of regional socio-economic.Research on the relations between the land-use and soil nutrient is important to exploring restoration of degraded land,at the same time this has a practical guiding significance on the sustainable use of land and ecological environment protection.Meta-analysis is a specialized statistic technology that can integrate the individual data under independent research,and now it has been developed into a research method.This paper describes the theory and steps of Meta-analysis in detail. It compares with the traditional overview as well in order to elucidate the advantages of this method.Then it is used in the field of purple soil area.In this paper, meta-analysis is used to analysis the Purple soil in farmland,woodland,orchard, grassland of four different land-use patterns including runoff,sediment,soil organic carbon,total nitrogen and total phosphorus five indexes comprehensively.Then it discusses the results.The following major conclusions are obtained:(1) It is compared with the bare land(that is,the coverage of trees and grass is zero) or the most severe erosion soil.As a result of the human activities and different infiltration characteristics under different land-use,there are different runoff and sediment reduction effectiveness among farmland,woodland,orchard and grassland. Overall,the characteristic of runoff is orchard＞woodland＞farmland＞grassland,the characteristic of sediment is woodland＞grassland＞orchard＞farmland.(2) There is a difference of the soil organic carbon contents among farmland, woodland,orchard and grassland under different land-use patterns.Descending order of soil organic carbon contents is woodland,farmland,orchard and grassland,but they do not reach the significant difference among the different land-use.In addition,this paper also examines the purple soil's soil nutrient contents under different types of land-use.The total nitrogen contents reach a significant difference among the four different types of land-use.In general it presented for woodland＞orchard＞farmland＞grassland.Grassland and woodland,grassland and orchard are in significant difference.However,four different land-uses of total phosphorus contents do not reach significant difference.The overall performance for total phosphorus is orchard＞farmland＞grassland＞woodland.(3) In this study,a correlation analysis is done among four patterns of Purple soil land-use within runoff,sediment,soil organic carbon,total nitrogen and total phosphorus.The results show that the farmland runoff and total phosphorus has an obvious positive correlation at the level ofαequal of 0.01.(4) Based on the results of analysis,it shows that the ways of returning farmland to forest and increase the vegetation coverage in the shallow purple soil should be used.According to the characteristics of purple soil,at the serious soil erosion region it should plant arborvitae,and at the less serious soil erosion region it should plant mixed forests.Purple soil is located in many hills and is mostly used as agricultural soil.Its water conservation capability is weak and water and soil loss is severe.Slope soil is very shallow and crop is prone to drought.This entire are greatly limited the development of agricultural production.Through this study we expect to find the best land-use in the purple soil hilly region and to provide a sustainable development of soil ecological environment and a theoretical basis of adjust land-use structure.