Affecting Factors And Storage Estimation Of SOC In The Topsoil

With the deepening research of the global warming, the global carbon cycle research hasbeen received more attraction by the scholar，becoming one of the three major hot spots of theglobal change research. The soil is the core of the terrestrial ecosystem, and connecting bondof the atmosphere, hydrosphere, biosphere and lithosphere. The soil carbon pools is the largestcarbon pool in terrestrial ecosystems, is also an important part of the terrestrial carbon pool.There are1.5*1015kg C in the global with the forming of the organic matters, and it is about2.5to3times for the total carbon storage of the land plants, and2times for the globalatmosphere. The changing of0.1%in the soil carbon pool will lead to the concentration of theCO₂in the atmosphere changing at millionth. The amount of the CO₂with the changing of10%in the soil carbon pools will equal to the amount of the emissions of human activities in30years. So, the smaller changing of the soil carbon pools will lead to the arise of theconcentration in the atmosphere directly with emission the warm air, and effect the changingof the global climate in the greenhouse.This paper take the Hedong district as the study case with the methods of fieldinvestigation, analysis of variance and regression correlation analysis to study the influencingfactors of soil organic carbon in the topsoil, and analysis the soil carbon pools and density.This paper select the influencing factors from two respects: the first is the natural factorsincluding soil types, topsoil types and topography types, the other is the human factorsincluding different tillage methods, different irrigation levels and different land using types.To analysis the soil carbon pool and soil carbon density use the methods of the soil types andland using types with the help of the GIS.（1）The clay contents of the soil have a significant effect on the soil organic carbon, thesoil types and the topsoil with more clay is benefit to the accumulation of the soil organiccarbon. The law under the different soil types is regosols<stony soil<brown<aquicsoil<shajiang black soil<paddy soil; the law under different topsoil is sandy loam<lightloam<middle loam<heavy loam. The elevation and the terrain will also effect the content ofthe soil organic carbon, the law under the different topography types is Lingcenwasteland<ordered land<slow plains<slightly inclined plains<tilt the ground.（2）In this paper, the study area is the topsoil in Hedong district, and the topsoil will beaffected mostly by the way of the human governments. Under the different vegetable types, the method of two crops a year is better for the accumulation of the SOC than the method ofone crops a year. The law of the different irrigation levels is no irrigation<basicallymeeting<generally meeting<fully meeting. The study showed that the more water in the soil,the more benefit for the accumulation of the SOC, but with the arising of the irrigation, thearising rate of the SOC is not apparent. The law under the different land using types isirrigated paddy fields<irrigated<dry land<orchard<vegetable land.（3）The SOC can increase the available of the other soil nutrient. The study showed thatthe SOC has a significant correlation with the TN、AK、 pH、AN、 SK、AFe and AMn atthe1%and the5%level, especially with the TN, the correlation coefficient is0.468. With theregression analysis between the SOC and the TN under the different land using types can getsuch equation: the irrigated paddy: y=7.6423x+2.7982，R²=0.6551;the irrigated: y=6.9993x+3.0241，R²=0.593; the dry land: y=7.8332x+2.0176，R²=0.7034; the vegetableland: y=7.3125x+2.5867，R²=0.4455;the orchard: y=9.4221x+0.3935，R²=0.8984.The result showed that: the SOC is better for the accumulation of the soil N than the otherland using types.（4）With the help of investigation and GIS, using the method of the soil types and the landusing types to analysis the SOC pools and the density in the Hedong district. With the methodof the soil types, the pools of the SOC is89.70*107kg, the mean density of the SOC is2.91kg/m2; with the method of the land using types, the pools of the SOC is90.18*107kg, themean density of the SOC is2.93kg/m2. The pools and the density of SOC in the middle andthe south part of the Hedong district is higher than other districts, the north part is the lowest.This result is related to the land using type and the soil types. The deep it is used, the higherthe SOC density will be.（5）The SOC in the Hedong district is in the high level. The farmland area could divideinto three government area: the first government area （C<9.54g/kg）, the area is7936.75hm2and it is25.52%of the total area; the second government area （11.83>C>9.54g/kg）, the area is14389.97hm2and it is46.27%of the total area; the third government area （C>11.83g/kg）, thearea is8773.31hm2and it is28.21%of the total area. The area which should be improved isthe north and the surrouding part of the hedong district.