| The estimation of carbon revenue and expenditure in crop farming and animal husbandry is of great significance to regional carbon reduction and development of low-carbon agriculture.In this paper,the methods of literature review and field investigation,carbon absorption parameter estimation in agriculture and animal husbandry,IPCC greenhouse gas emission inventory,sample observation and experimental analysis are used.Through the estimation of agricultural and animal husbandry in Muchuan County for nearly 21 years(1996-2016)and nearly 13 years in the villages and towns(2004-2016),the agricultural and animal husbandry production carbon absorption,carbon emission,carbon intensity and carbon sustainability index are estimated at county scale.Through this study,we hope to provide theoretical research for low carbon development of agriculture and animal husbandry.The following conclusions are obtained through the study:(1)In the last 21 years,the agricultural structure in Muchuan county was dominated by planting and animal husbandry(accounting for 49.50% and 32.80%respectively),and the planting industry showed a downward trend.The proportion of paddy fields and dry land in cultivated land tends to be close to each other(54.25% and45.75% respectively).In the last 21 years,the area of grain crops has decreased significantly,and economic crops have shown an increasing trend.The multiple cropping index rose slightly,with an average of 246.71%.Per unit area yield of crops show an increasing trend.The biggest change was wheat,followed by yellow ginger and rice.The coefficient of variation was 0.72,0.56 and 0.03,respectively.The input of cultivated agricultural land area is increased.Only the amount of cattle reared in Muchuan County's animal husbandry has declined.Each town in the flat areas in the northern part of Muchuan County has a higher level of production in crop productionand animal husbandry,and poultry and rabbits are mainly concentrated in eastern areas.(2)The average annual carbon uptake of Muchuan County in 1996-2016 years is100 thousand and 400 tons,showing a downward trend of fluctuation,and the carbon uptake intensity fluctuates.The carbon absorption of crops and forage grass accounted for 99.86% and 0.14%,respectively,and the proportion of the former decreased.The amount of carbon absorbed by crops was dominated by the major spring crops(69.54%),and rice accounted for 38.91% of the crops.The average annual carbon emissions of agriculture and animal husbandry is 35 thousand and 200 tons,showing a downward trend of volatility,and the intensity of carbon emissions is increasing.Rice fields and livestock and poultry accounted for 41.57% and 33.26% respectively.The winter paddy field(growth period)accounted for 48.16% of the paddy field emission,and the agricultural investment carbon emissions were mainly chemical fertilizer(76.27%),and the carbon emissions of livestock and poultry were dominated by cattle(49.04%)and pigs(35.06%).The average annual net carbon absorption was 65,200 tons,a decrease of1.50%.Net carbon absorption intensity is 4.56 tons / ha,showing an upward trend of volatility.The average annual carbon sustainability index is 1.87,showing an upward trend in general.(3)The major carbon crops in Muchuan county are mainly in the west to central and east central parts.The biggest is Zhouba town(0.64 million tons).The carbon uptake intensity of the southwest and middle east is relatively large,the largest is the town of Lidian town(9.53 tons/ha),and 42.11% of the towns are between 5.00-6.00tons/ha.Carbon emissions and carbon emission intensity were all higher in the northeast than in the southwest area,the largest is the Dibao town(0.20 million tons)and the Dnnan town(2.57 tons/ha).The carbon emission intensity of all villages and towns decreased.52.63% of the township carbon emissions intensity is greater than 2 tons/ha,concentrated in the north part.84.21% of the villages and towns are mainly rely on carbon emissions from rice fields.There is carbon surplus in each town,and net carbon absorption in Lidian town is the largest(0.47 million tons).The net carbon uptake intensity of the annual average unit area of cultivated land is the largest in Lidian town(7.74 tons/ha).73.68% of the town's net carbon absorption intensity increased,and42.11% of the town's sustainable carbon index was less than 3.50.(4)The carbon budget of Muchuan county and each town was analyzed to get the problem of carbon budget in agriculture and animal husbandry in Muchuan County:with the decrease of the main grain crop yield,the carbon absorption was also decreased.Paddy fields(41.57%)and livestock(33.26%)are the key carbon sources.52.63% of the town's carbon absorption intensity has decreased.In the northeastern area,the carbon emissions and their intensity of the rice field,livestock and poultry are high.The following measures should be taken as follows: emphasis should be placed on improving the production methods of carbon sources and regions with large emissions,promoting low carbon technology,such as adjusting the planting system,improving the farming methods and techniques of rice fields,improving the technology of livestock and poultry breeding,promoting large-scale farming,vigorously promoting the technology of agricultural investment,strengthening the comprehensive utilization of resources,government guidance,and actively change the farmer's concept and behavior of agricultural land use. |
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