Characteristic Study Of Soil Organic Cardon In The Process Of Sandy Desertiification

The Erdos sand land is a typical sandy desertification area. In this study, by taken a lot of soil samples and field observation, the soil organic carbon, total-N, total-P, available-P, available-K, different active organic carbon, the content and constituent of humus, different combined humus of soil organic-mineral complex on the degraded gradient were determined and statistically analyzed. The main result as follows:1. By determining and analyzing the soil organic carbon, total-N, total-P, available-P, available-K under different degenerated stages of plant community, it revealed that as the desertification status worsening the nutrient contents such as total-N, total-P were reduced obviously.2.On the desertification gradient, the humus constitutes were changed. Soil organic matter content, humic acid content decreased obviously, The organic-mineral complexes in surface soil changed obviously under different degenerated stages and in the recovery process of Erdos sandy grassland. It showed the humus in organic-mineral complexes mainly existed with loose combined form (26%~51%), tight combined form (32%~49%), and a few stable combined form (9%~37%). All Humus content in the loose-form, tight-form and stable combined form decreased as the diameter of organic-mineral complex increased.3.ON the degraded gradient, three different active carbons content of each layer in soil profile was decreased from surface soil to the bottom. The change trends on the profiles under different degraded stages were similar. The t-tests showed three different active organic carbon content of soil surface (0~5cm) had remarkable difference under three-plant community.4. By analyzing the spatial variability of surface soil organic carbon under three plant communities and linear surface soil organic carbon under different degenerated gradient, we found that in Erdos sandy desertification area the soil organic carbon around shrubs has a remarkable spatial variability and structure. The analysis of linear surface soil organic carbon under different degraded stages and on the recover process by fencing treatment d revealed that soil organic carbon content was related with the distribution of plant community, the nearer the distance is from the plant, the more the soil organic carbon content was.