Temporal And Spatial Changes And Prediction Of Carbon Budget In Planting And Animal Husbandry In Guangyuan During The Last 25 Years

Based on discussing the characteristics of agricultural structure in Guangyuan City,parameter estimation method and IPCC inventory estimation method are used to estimate carbon budget and expenditure and net carbon sink of planting and animal husbandry during the last 25 years（1995-2019）,and to analyze its temporal and spatial dynamic characteristics.Based on GM（1,1）and ARIMA model,the carbon emissions of planting and animal husbandry in the next six years（2020-2025）in this city and everry counties or districts were predicted,as well as the change trend and regional differences.According to existing problems of low-carbon agriculture development in this city,the corresponding low-carbon development countermeasures are put forward.The main research conclusions are as follows:（1）During the last 25 years,the agricultural structure of Guangyuan City has been dominated by planting industry（46.79%）and animal husbandry（41.20%）,and has shown a diversified development trend.There are significant differences in agricultural structure among counties in the city.The agricultural structure of various districts and counties has significant differences;The annual multiple cropping index of the whole city is 251.92%,showing a fluctuating increasing trend;the ratio of crop sowing to grain to grain was 77.76:22.24.The yield per unit of rice and corn is higher in grain crops,and the yields of peanut and canola are higher in cash crops,both of which show a fluctuating upward trend.The annual average intensity of agricultural inputs was the largest in terms of fertilizer input intensity（4.48t/hm2）,and the intensity of planting inputs showed a fluctuating upward trend.In animal husbandry structure of the city,pigs accounted for 74.37%of the livestock;pork products accounted for 82.01%of the output of livestock and poultry,showing a fluctuating upward trend.The regional differences in the agricultural structure of the districts and counties in the city are obvious.（2）During the last 25 years,the annual average carbon absorption of planting industry was 17.58 ×105t,and the average annual carbon absorption intensity was 9.68t/hm2,both of which showed a fluctuating upward trend in Guangyuan City;the main crops absorbing carbon are spring crops（42.71%）,showing an increasing trend,which is on the rise.There were significant differences in carbon absorption among districts and counties.Among them,Jiange had the largest carbon absorption intensity（12.57t/hm2）and Qingchuan（5.47t/hm2）the smallest.The city’s annual average carbon emission from planting and animal husbandry was 86.32 × 104t,and annual average carbon emission intensity was 5.46t/hm2.The former showed a fluctuating downward trend,while the latter showed a fluctuating upward trend;Among the characteristics,planting industry（57.49%）was larger than animal husbandry（42.51%）.The carbon emission intensity was composed of livestock and poultry breeding（42.54%）>farmland soil（20.68%）>agricultural input（20.61%）>straw burning（16.17%）,and the carbon emission intensity of each category fluctuates greatly.The high carbon emission intensity areas were concentrated in Cangxi and Jiange counties,and there were significant differences in carbon emission intensity among different carbon source categories in each district and county.The city has shown a net carbon sink effect during the past 25 years.The annual average net carbon sink was 83.94 × 104t,and the annual average net carbon sink intensity was 4.12t/hm2,both of which showed a fluctuating upward trend.There are significant differences in net carbon sinks among districts and counties,with Jiange accounting for the largest annual average net carbon sink（47.37%）,and Lizhou District the smallest（2.97%）.There was a great spatial differences in the intensity of net carbon sinks in the city.The carbon revenue and expenditure and the center of gravity of the net carbon sink of each district and county were all located in Zhaohua.The carbon absorption has increased in the northwest and the center of gravity of carbon emissions was inclined to the south.The change of the net carbon sink was complicated and moves to the south as a whole.（3）In the next six years（2020-2025）,the carbon emissions of planting and animal husbandry in Guangyuan will fluctuate between 80.85 × 104t～83.17 × 104tt,showing a downward trend;The variation range is 54.05 × 104t～56.23 × 104t,showing an upward trend;the variation range of animal husbandry carbon emission is 25.29 × 104t～28.42 × 104t,showing a downward trend.The city’s planting and animal husbandry carbon emissions vary greatly among regions.Except for Zhaohua（5.99%）and Cangxi（2.34%）,which showed an upward trend,all other districts and counties showed a downward trend,and the decline was followed by Lizhou（8.73%）.%)>Qingchuan（7.26%）>Jiange（6.72%）>Wangcang（1.16%）>Chaotian（1.09%）;the carbon emission of planting industry will show an upward trend in the next six years,and the increase rate will be Lizhou（0.58%）Lizhou（17.97%）>Wang Cang（16.77%）>Jiange（13.68%）>Chaotian（7.39%）>Cangxi（7.24%）.（4）There are problems in the development of low-carbon agriculture in Guangyuan City:the carbon emission of the planting industry will further increase in the future;the inter-annual fluctuation of crop carbon absorption is large,and the regional differences are significant;the use of chemical fertilizers in agricultural inputs accounts for a large proportion of carbon emissions,and the use of chemical fertilizers and agricultural film The carbon emission of straw burning is increasing rapidly,the carbon emission of corn stalk burning accounts for a large proportion,and the carbon emission of rape straw burning has the fastest growth;the carbon emission of animal husbandry production accounts for a prominent proportion,and the utilization rate of livestock and poultry manure is low.In the future,the following measures can be taken:attach great importance to the carbon emissions of the planting industry,and promote the scale and low-carbonization of the planting industry;strengthen the construction of farmland infrastructure according to local conditions,stabilize agricultural production and crop carbon absorption;Efficiency;mainly corn and rapeseed,strengthen the efficient utilization of crop straws;improve breeding technology and strengthen the comprehensive utilization of livestock and poultry manure.