| This paper takes the Yuanzhou District of Guyuan City and the Ansai District of Yan'an City in the loess hilly region as the research areas.The CSLE model is used to make a preliminary exploration of the soil erosion status,and the detailed data obtained by combining the results(erosion modulus)with field investigation And statistical data,using the emergy analysis method to quantitatively analyze the input and output of the agricultural systems in the two regions,and evaluating the coupling between agriculture and resources and environment through emergy indicators,and discussing whether the local resource environment supports agriculture through corresponding input structures and indicators Development,the sustainability of local agriculture,revealing the problems and causes of its agricultural development,and evaluating the comprehensive benefits of the local agricultural industry.The conclusions are as follows:(1)The main land types in the study area are grassland and cultivated land.Due to the impact of the project of returning farmland to forest,from 1995 to 2017,the farmland in Ansai District decreased by 369.09km2,the area ratio decreased from 42.41%to 30.03%;forest land and grassland increased by 170.20 and 184.64 km2,accounting for 5.45%and 51.57%respectively increased to 11.24%and 57.85%.The land use change in Yuanzhou District was relatively small,with cultivated land and grassland decreasing by 45.05 and 1.71km2,respectively,and forest land increasing by 0.07km2,accounting for 41.48%,45.31%and 7.63%,respectively,from 43.32%,45.61%and 7.66%.(2)Ansai District changed from strong erosion(1995-2000)to moderate erosion(2008-2017),the erosion modulus decreased from 6107.9 t/(km2.a)to 2763.9t/(km2.a),a decrease of 54.75%;the type of erosion changed from micro,moderate,and extremely strong(1995-2000)to micro,mild,and moderate(2008-2017),and the proportion of moderate and above areas was 65.5%It fell to 46.4%.The Yuanzhou District is mildly eroded,with the erosion modulus decreasing from 1943.6 t/(km2·a)to 1210.9t/(km2·a),a decrease of 37.70%;the types of erosion are mainly mild,mild and moderate erosion.The proportion of moderate and above areas decreased from 26.3%to 17.8%.(3)The breeding industry in Ansai District is due to its small breeding scale and relatively small input of various resources.The utilization rate of purchased energy is high,the production efficiency is good,and the average annual output investment ratio is the highest,and the product profit is high.At the same time,there is less pressure on the local area,so it has become the most sustainable industry in the local area.Yuanzhou District's plantation industry system has a higher percentage of annual environmental input and a lower proportion of non-renewable resource inputs,indicating that Yuanzhou District's plantation system is more self-supporting and has a higher utilization efficiency of purchased energy value.The environmental pressure is relatively small,and the average annual investment ratio is higher.Therefore,the plantation industry in Yuanzhou District has a better coupling degree with the local resource environment than the aquaculture industry and has better sustainability.(4)Among the different types of districts,the total emergy of the input and output of the plantation and aquaculture systems of Yuanzhou District is higher than that of Ansai District.Compared with Ansai District,the planting industry in Yuanzhou District has more environmental resources and less non-renewable resources,indicating that its system is more self-supporting,less dependent on purchase emergy,and has lower production costs and market competitiveness.Higher,less environmental pressure,greater development potential,and greater sustainability.The planting industry in Ansai District needs to strengthen the utilization rate and mechanization of local renewable natural resources.Compared with Yuanzhou District,the breeding industry in Ansai District does not have a large area of forage cultivation.The utilization of purchased energy is lower,the production cost is lower,the environmental pressure caused is also less,and the ratio of production to investment is higher,and the economic benefit is better.Keep going stronger.Yuanzhou District can properly reduce the scale of breeding and reduce the environmental pressure caused by the cultivation of forage crops in the breeding industry... |
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