Farming Practices On Carbon Sequestration And Emission Mitigation In Double Rice Field And Adoption Behavior Of Low Carbon Technology By Rice Farmers

Paddy field is the third largest greenhouse gas(GHG)emission source in the agricultural sector,which accounts for 10%of the GHG emissions in agricultural.Therefore,the development of low carbon agriculture in paddy fields is the key to the sustainable development of agriculture in China.This study used statistical data,survey data,and field experiment data to make clear the change of carbon footprint(CF)and its influencing factors under the background of climate change in the double cropping rice region of Sourthern China in the past ten years,further analyzed the potential and strategies of reducing CF in the way of optimizing farming practices,and quantitative analysis on the factors that affect rice farmers' adoption behavior on low-carbon technologies(LCTs)was launched to provide scientific basis and reference for the construction of low-carbon rice-producing technology system in China.The main conclusions are as follows:(1)The CF of early and late rice in each province tended to increase,and CH4 emission played major role.The highest components of hidden greenhouse gas emissions in double cropping rice is the production,transportation and utilization of fertilizers(60%).Progressive regression analysis showed that hidden greenhouse gas emissions of double-cropping rice production from 2004 to 2014 were mainly affected by diesel,compound fertilizer and K20 fertilizer.CF of early and late rice in Zhejiang,Guangdong and Hainan were the highest at about 0.90 kgCO2-eq kg-1,and Anhui,Fujian,Hubei and Guangxi were lower at about 0.50 kgCO2-eq kg-1.Anhui and Hubei provinces were low-emission with high-income provinces when concerning net profit income,which benefited the sustainable development of low-carbon rice production.(2)With the increasing experimental time,the C sequestration rate in no-till(NT)was accelerated,and the accumulation of SOC gradually became significantly higher than that of plow tillage(PT).Long-term NT treatment significantly reduced net annual global warming potential(NGWP),largely depending on the reduction of CH4 emissions.The CF also showed lowest in NT(0.99 kg CO2-eq kg-1)in case of yield increased significantly.The water-saving irrigation significantly reduced the SOC in the surface soil,while the active organic carbon(AOC)content showed the opposite trend.Intermittent irrigation(II)tended to significantly increase CH4 emissions during the rice growing season and significantly increased N2O emissions from drained soils during the nonrice season.Water-saving irrigation significantly increased grain yields due to the dramatically increase of effective panicle number and filled grains per panicle.II treatment reduced the CF of the double cropping rice by 44%compared with flooded irrigation(FI).Among nitrogen(N)treatment,yields increased with the increase of N application rate,but without significant difference between N1(farmers' N application rate)and N2(20%reduction).The annual soil C sequestration rate decreased with the decrease of nitrogen application rate in paddy field,but without difference significant(P<0.05).Reducing N usage can effectively decrease CF in the double-rice cropping system,with the lowest CF obtained in the N2 plot(0.99 kg CO2-eq kg-1 year-1),which was reduced by 34%compared to N1 treatment.(3)This chapter choosed seven typical LCTs including low-carbon and high-efficiency varieties,no-till technology,optimizing fertilizer management,water-saving irrigation,pesticide reduction technology,winter fallow field management,planting-breeding technology in double cropping rice of Hunan province.The results of the MVP model analysis showed that there were complementary and alternative relationships in the process of the adoption of the seven technologies.There was a complementary relationship among fertilizer optimization management,no-till technology and winter fallow field management,while the adoption of pesticide reduction technology,planting-breeding technology and winter fallow field management had alternative effects.Older farmers were less willing to use labor-output LCTs,such as water-saving irrigation and winter fallow field management,but larger number of family members benefited the adoption of these technologies.In addition,the higher level of farmers' education,the easier it was to adopt challenging LCTs such as no-till technology and planting-breeding technology.Increasing farmers' awareness on climate change was key to significantly help farmers to adopt low-carbon farming technologies.Enhanced government subsidies and technical services,as well as the ease of loaning,can effectively reduce the threshold of LCTs adoptions by farmers,particularly in water-saving irrigation and planting-breeding technology.