Potential And Incentive Mechanism Of Soil Organic Carbon Sequestration In Cropland Of Yangtze Delta Plain

Soil carbon sequestration is a growing research topic that addresses one important aspect of an overall strategy for carbon management to help mitigate the increasing emissions of CO2 in the global climate change research. Carbon in agricultural soils is disturbed by anthropic management acutely, but it still can act as sinks for carbon dioxide and other greenhouse gases through the recommend management practices in soils. To know the effect of soils on carbon sequestration and also its potential contributes to the drawing of justice and reasonal list of carbon mitigation, and international envrioment agreement. The "Bali roadmap" was adopted for a future international agreement on climate change in the United Nations climate change conference in Bali in December,2007. After that, for the initiatives in the climate change negotiate, a lot of integrated programs on soil carbon in agricultural land were started up by nations in the world, especial in developed countries.Increasing evidences demonstrated that the agricultural soils especial paddy field soils had large potential on carbon sequestration. Therefor, it can play an important role in reducing the stress of greenhouse gas mitigation for the country. However, the effect and potential for carbon sequestration in cropland soils still has a lot of uncertainty in China. It is exigent of understanding about the effect and potential of cropland soils for carbon sequestration, and also the measures to realize it. As a developed region which has long history of rice cultivation in China, carbon emission in Yantze delta plain was considerable. Base on abundant material such as long-term field observation dataset, our objectives were to assess the carbon sequestration effect and potential of carbon sequestration thchonogies applied in Yangtze delta plain, and in turn to establish incentive mechanism for carbon sustainable management in this region.Spatial characteristics analysis on soil organic carbon content changes about more than 20 years based on long-term observation data was done using GIS technology, firstly. Secondly, the role of natural factors and anthropic factors on soil organic carbon content were discussed through the factors analysis; Thirdly, carbon sequestration effect of typical carbon sequestration technologies in this study region was analyzed through the Meta-analysis of long-term field experiments data. Then, based on the peasant household survey, and analysis with of peasant household behavior model, the application status of typical carbon sequestration technologies and the affect factors that influence farmer behavior of carbon sequestration technologies application were disscussed, respectively; The cropland soil carbon sequestration potential under the scenarios assumption that the use of typical carbon sequestration technologies in this region was simulated using Rothc model; Finally, to sum up the results of above, the incentive innovation system to promote soil carbon sequestration technologies application in the region was designed. The all results are as follows:The soil organic carbon content of cropland increased in general and was a sink for carbon dioxide since 1980 in Yangtze delta plain. The soil organic carbon content was 19.5% higher in 2006 than that in 1980. The enhancement of soils varied in different soil types and was highest in fluviogenic soil which its soil organic carbon content increased from 6.9g/kg to 10.8g/kg. The soil organic carbon content of paddy soil enhanced 11.0%. The distribution characteristics of soil organic carbon content changed in different periods but showed a trend of higher in the south and lower in the north in general. Soil organic carbon content of cropland in north of Yangtze delta plain increased significantly on average and showed the trend for carbon sink.Geostatistics method, conducted by Geographic Information System (GIS), was applied to analyze the spatial variability of soil organic carbon content in cropland. The results showed that the spatial variability of soil organic carbon content in the recent 20 years increased. The range was 41.5km in 2006 while it was 274.9km in 1980. The ratio of null and sill(Co/(Co+C)) enhanced from 28.1% to 49.8%. It can be concluded that the variability induced by random factors such as farming system or agricultural management increased. In the other hand, the variability induced by structural factors such as climate, soils types or soil parent material. Factors analysis indicated that anthropogenic factors reduced the influence of natural factors on soil organic carbon content, and showed rather important effect on the soil organic carbon management. In particular, the special cropping pattern in paddy field contributed to carbon sink in this region. This dissertation conducted Meta-analysis to compare the carbon sequestration rate and duration of several typical carbon sequestration technologies in Yangtze delta plain.The results showed that there were significant effects of straw returning and animal manure application on carbon sequestration, which could enhance soil organic carbon content by 0.41t ha-1 yr-1 and 0.34t ha-1yr-l on average during the experiment period, respectively. Whereas there was no significant effect of reduced/no tillage on carbon sequestration in the study region. Greater effect of carbon sequestration was obtained in triple cropping systems with double rice seasons than double cropping systems with single rice season. Straw returning and animal manure application could enhance soil organic carbon content at the durations of about 20 and 40 years, respectively.The analysis based on peansant household investigation showed that the status of soil carbon sequestration technology application varied during different sites in this region. Factors analysis conducted by peasant household behavior model showed that the main factors which influenced the application behavior of carbon sequestration technology varied in different areas. In more developing regions, the margin cost of treatment with straw was crucial factor that influenced the behavior of straw returning, whereas the benefit of straw was priority considered in less developing regions. The pivotal factors which influenced the application behavior of animal manure were whether having livestock and poultry farming or not, as well as the level of surplus labor. It can be concluded that when establishing incentive policies for the popularization of carbon sequestration technologies in agricultural soils, full consideration should be given according to the basic characteristics of agricultural production in different areas.Soil organic carbon dynamics in Yangtze delta plain was simulated using RothC model under different scenarios. The results showed that carbon sequestration rate varied. It could reach at 0.37 t ha-1 yr-1 and 0.70t ha-1 yr-1 in the first 20 years on average under the scenarios of half straw returning and whole straw returning, respectively. Under the scenario of organic fertilizer utilization, carbon sequestration rate was 0.36t ha-1 yr-1 and 0.68t ha-1 yr-1 under 1.5t C and 3t C organic fertilizer application, respectively. The carbon sequestration effect was 0.69t ha-1 yr-1 under the compounding utilization of half straw returning and 1.5t C organic fertilizer, which was between the effects under whole straw returning and 3t C organic fertilizer scenarios. The spatial distribution of carbon sequestration potential seemed higher in the north of the region in the scenarios of half straw returning or 1.5tC organic fertilizer application. On the contrary, it was higher in the south of the region under the scenarios of others. In the terms of carbon sequestration cost, whole straw returning, application of 3 tC organic fertilizer and compounding utilization of half straw returning and 1.5t C organic fertilizer had the highest benefit-cost ratio.A comprehensive system of incentive mechanism innovation should be implemented in order to promote carbon sequestration technologies applications in cropland soils in this region. The main three aspects of incentive innovation, those was mechanism of strengthening the farmer's sustainable self-development, the participatory mechanisms of technical implementation, and fair and effective mechanisms of the government supporting. To improve farmer's awareness of efficiently recycling of agricultural wastes resources and the achievement of sustainable development of agriculture, as well as their own; To innovate and promote the implementation mechanisms, and thus to conduct the implementation effectively and efficiently; To improve a wide range of compensation incentives, eco-efficiency of the compensation mechanism, industry support mechanisms, as well as technical support service mechanisms; To inspire farmers for the application of agricultural soil carbon sequestration technologies more extensively, and also to take soil carbon sequestration as a long-term agricultural policy for sustainable development of agriculture.