The SOC And Components' Characteristic Under Different Land Utilization Patterns In Karst Small Watershed Of Guizhou Province

This study was conducted in the karst small watershed of chenjiazhai, Puding County, Guizhou province, used soil physico-chemical fractionation procedure, through the traditional statistics and geostatistics combining method to study the soil organic carbon and components characteristics under different land utilization patterns. The study had an important significant to understand soil organic carbon and its components' fixed and stability mechanism, so did the management of the land use patterns. The results show that:(1) The average soil total organic carbon and the soil active organic carbon in all watershed is 36.33g·kg-1 and 8.79g·kg-1. The soil total organic carbon and soil active organic carbon have the similar trends in the different land use patterns, the order in various land use patterns is shrub land>artificial forest>unused grassland>garden plot>cultivated land and they have a better significant differences. The results show that the land use patterns have obvious impact on SOC and SAOC. The correlation analysis indicated that soil total organic carbon and the soil active organic carbon have a significant positive correlation and soil active organic carbon can sensitive to the reaction of soil organic carbon.(2) Using the soil physico-chemical fractionation procedure method, we get different components. The components of soil SOC have similar variation trends. There is great difference among the components in the five different land use patterns and show that unprotected SOC is the highest, followed by chemically-protected SOC and biochemically-protected SOC, physically-protected SOC is the lowest. The unprotected SOC ? physically-protected SOC and stabilization component SOC components of the soil in the different land use patterns have some variation trends and have similar variation trends to STOC, besides unprotected SOC has significant difference. This shows that, compared with other components of organic carbon, unprotected SOC more sensitive to changes in land use patterns. Through correlation analysis showed that the four protection mechanisms both have the significantly positive correlation to STOC.(3) The geo-statistical analysis showed that both soil organic carbon's and soil active organic carbon's space relation were moderate, the relevant range were 399.95 m and 327.61 m. According to the results of Kriging spatial interpolation, spatial distribution of soil organic carbon and soil active organic carbon are similar, both have gradient variation of patch mosaic distribution, so indicated that they have better spatial correlation in some small watershed. Elevation has more impact than land use patterns on soil organic carbon and soil active organic carbon.