Research On Sustainable Development Of Agricultural Ecosystem In Yonghe County Based On Emergy Theory

Abstract As the primary industry,agriculture is the basis for human survival and the guarantee for the development of the national economy.The sustainable development of agriculture is one of the important prerequisites for the sustainable development of human society.However,unreasonable agricultural activities and excessive consumption of natural resources by humans have led to severe damage to the stability and sustainability of agricultural development.The hilly area of the Loess Plateau was once an important agricultural production base.However,due to unreasonable agricultural activities of human beings,it is now an area with shortage of resources,serious soil erosion and a fragile ecological environment.The agricultural production is backward and the people live in poverty.Since the national implementation of a series of ecological projects in the early 21st century,the agricultural production structure and land use structure in the region have also been adjusted,and the ecological environment has improved significantly.Therefore,the paper selects Yonghe County,a typical county in the loess hilly region of the Loess Plateau,as a case study,and quantitatively analyzes the input and output of the energy value of agricultural ecosystem in Yonghe County from 2000 to 2015 based on the emergy theory and method.Value self-sufficiency rate,environmental load rate),economic indicators(emergy value investment rate,net energy value output rate),sustainable development index,and a comprehensive study of the sustainable development capacity of the agricultural ecosystem in Yonghe County.The results show:(1)The total input energy value of agricultural ecosystem in Yonghe County in 2014 is 2.40E+20sej,and the total output of emergy is 1.11E+20sej.In each of the emergy inputs,the maximum amount of non-renewable industrial auxiliary energy input is 1.11E+20sej,which accounts for 46%of the total input energy value.Among the various output energy values,the highest emergy output in the cropping industry is 1.55E+20sej,which accounts for 60.3%of the total output energy value.(2)According to the analysis of the indicator system of the agroecosystem in Yonghe County in 2014,Yonghe County's agroecosystem as a whole performed well,causing less pressure on the environment and being at a low level of sustainable development.However,in agricultural production,the input value of auxiliary energy value is insufficient,and the natural environment resources are not fully utilized,which restricts the further development of agriculture.From the analysis of emergy density and per capita energy consumption,people's living standards are not high.(3)The energy input-output structure of the Yonghe County agro-ecosystem is continuously optimized,the agricultural production efficiency is gradually improved,and the output of the agricultural ecosystem gradually shifts from a loss-making state to a profitable one,but the system is more dependent on natural environment resources.Insufficient investment in economic energy value and inadequate use of natural environment resources have restricted the further development of agriculture.During the past 16 years,Yonghe County's agricultural ecosystem functioned as a whole,and its sustainable development capacity was in a low degree of sustainable development,but it was not stable enough.(2)From the perspective of energy input analysis,during the research period,renewable energy resources can make a great contribution to agricultural production.The renewable organic energy value and the non-renewable industrial auxiliary energy value show a shift.Trend.(4)From the results of energy output analysis,during the research period,the energy output of the agricultural system in Yonghe County was significantly improved,and the output structure was a dual structure dominated by crop cultivation and animal husbandry,and it was developed into crop farming,forestry,and livestock husbandry.The industry is three-fold and the dominant industries are gradually becoming more prominent.In view of this,it is suggested that the research area further optimize the input structure of energy value and improve the efficiency of system operation;carry out structural reforms on the supply side of agriculture;develop characteristic high-efficiency agriculture;strengthen ecological environment treatment,curb water and soil loss,and increase the utilization rate of water resources.