Crop Productivity And Carbon Sequestration Effect Of Paddy Field Under Different Management In Southern Jiangsu

Globle climate change, caused by increased emissions of carbon dioxide, is likely to affect agroecosystems and human's daily life, therefore carbon sequestration had been paid so much attention that lots of countries have been carrying on studies about carbon sequestration in paddy soil ecosystem, meanwhile, reference to household behavior response to carbon sequestration techniques, so as to make conservation tillage policies and establishing incentive mechanism. Although the conservation tillage is popularization for a long time in China, there is still much room for improvement in deeper study about effect of carbon sequestration techniques and widely generalizing new techniques. To study on carbon sequestration effect and bousehold behavior under different treatments in paddy soil is important to understand effect of carbon sequestration techniques, main elements influencing famer's behavior and setting up corresponding policies. This paper taking Wujiang county of Jiangsu province as an example used EXCEL and SPSS software to study the change of soil quality and farmer's production behaviors. Conclusions have been drawn as follows:1. Look no further than crop productivity in paddy, danymics of grain annual productivity and biomass yield under diffirent management showed volatile increasing Trends. Most index of integrated implication with organic manure and chemical fertilizers is higher than other fertilizers; productivity in blank-control area is below other management, and the yield shrunk year by year; Indexs of fertilizers only or non-N management is decreased speedly till 2001, grain annual productivity and nitrogen use efficiency had dropped by 41.03% and 64.68%. Grain annual productivity and biomass yield in straw application management both all year and autumn stady highest standard. Grain annual productivity of all year straw application increased 101.19%. Grain annual productivity of blank-control area and fertilizers only or non-N area fluctuates obviously. To analyse the nitrogen use efficiency of rice, nomal fertilizers area is highest, and the lowest is fertilizers only or non-N management. It dropped by 64.68% till 2005. Nitrogen use efficiency of all-year strew application and autumn strew application area increased obviously, greater than 3kg/kgN, and it recorded a rise of 63.46% and 48.39%; Other fertilizers used area increased less. Conclusions showed that integrated implication with organic manure and chemical fertilizers and all-year strew application played important rule in increasing crops productivity.2. Analysising on dynamic characters of SOC and soil total nitrogen, SOC of most management except blank-control is more than 1988 standard. Index of integrated implication with organic manure and chemical fertilizers management grow 3.0g/m~2, 22%. Change of soil total nitrogen under different management is different from dynamic characters of SOC. Increment of soil total nitrogen is greatest than others, which reached 30.2% and increased 0.48g/m~2. Content of soil total nitrogen in nomal fertilizers and blank-control management decreased 10.6% and 3.6%. Take soil C/N into account, Value of integrated implication with organic manure and chemical fertilizers and fertilizers only or non-N area decreased. Integrated implication with organic manure and chemical fertilizers management dropped greatest, which the value decreasd from 10.1% to 7.9%. Soil C/N of blank-control area increased most, which increased 11 percent. Soil C/N of autumn strew application is highest than others, which reached 8.5. Soil organic carbon density trend is same to soil C/N. Increment of integrated implication with organic manure and chemical fertilizers management is greatest, which increased 22.03%. SOC density of blank-control decreased 5.26%. Furthermore, organic carbon in surface soils trend fluctuate obviously, which increment in integrated implication with organic manure and chemical fertilizers management area is greatest and range is smallest, which the value reached 0.37kg, and the increscent range is 22%; SOC in blank-control trend decreased. Other management showed increscent.3. According to researches from farmers' surveys, there were significant differences between farmers in options of administration of farmland and technology. Agricultural management scale, benefit and the rural work force was the key factor that farmers decided the conservative technology on farmland. The total income that each farmer owned was decreasing and the rate of straw return was dropping. There was a negative correlation between rural work force and the use of organic fertilizers and rape planted choice.