Researches On Soil Organic Carbon Density And Carbon Sequestration Effects In The Farmland Of Yangtze Delta

The increasing concentration of greenhouse gases in the atmosphere affected by the human activity will quicken the step of global warming trend and increase the frequency of extreme weather, and whether the climate will get worse or not will be determined by the soil carbon stocks response to the global climate change. Researches on the dynamics mechanism, the sequestration potential and spatial distribution of soil organic carbon in the farmland will contribute to evaluating the soil carbon response to the climate change reasonably and foreseeing the climate in the future exactly. The cropping system alternation in the paddy field in the Yangtze Delta where there are typical paddy soils and cropping system takes the lead in the South of China, so studies on the estimate of carbon sequestration potential and the analysis on the carbon sequestration technology in Yangtze Delta will make it an meaningful example both in potential assessment and technology selecting for carbon sequestration in farmland soils in the South of China and even the whole country.Based on the data of the second national soil survey in China, some published-data from long-term field experiments and farm household investigation, the paper analyzed the characteristics of soil organic carbon in the plow layer of farmland, estimated the carbon sequestration effects through constructing the carbon dynamics model and studied the factors which has influence on the carbon sequestration technology selecting in Yangtze Delta. The main results are as follows:1. Soil organic carbon density in the plow layer of farmland in Yangtze Delta: Results showed that the soil organic carbon density was about 1.52 kg/m~2 in the dry land and 2.63 kg/m~2 in the paddy field which were both lower than that of in the whole China, respectively, and also we can see that the soil organic carbon density in the paddy field was 73% higher than that of in the dry land in Yangtze Delta compared to that of only 13% in the whole China. Furthermore, analysis indicated that the influence of natural factors on the soil organic carbon density decreased. These results suggest that anthropogenic disturbances have great impacts on soil organic carbon density in farmland soils, especially in paddy soils, indicating a high control potential of soil organic carbon density.2. Carbon sequestration effects of conservational farming systems: Assessment model of the change in soil organic carbon density induced by conservational farming systems in paddy fields in Yangtze Delta has been constructed. Based on this model, soil carbon sequestration effects of conservational farming systems were primarily assessed according to the changes of the farming system in the past 20 years in this region.