Shuo CAO，Shunqiang SUN

College of Economics and Management，Southwest University，Chongqing 400715，China

1 Introduction

Circular agriculture is a new agricultural developmentmodelwhich combines the theory of circular economy and sustainable development，and a new way to achieve agricultural economic growth while coordinating the population and resources＆environment［1］.Chinese scholars'studies of circular agriculture aremainly focused on the definition of circular agriculture（Xuan Ya'nan et al.，2005；Guo Tiemin et al.， 2004； Zhou Zhenfeng et al.，2004）［2-4］；the necessity of developing circular agriculture in China（Zhou Zhenfeng et al.，2004；Li Rongsheng，2005；Ma Jiang，2005）［4-6］；analysisof developmentmodelof circular agriculture（Yin Xundun et al.，2005）［7］.The evaluation of the development of circular agriculture ismostly the comprehensive evaluation of the developmentof circular agriculture in a country or region，and few studies are performed on the evaluation of agricultural industrymodel of businesses and farms.In this paper，based on numerous evaluationmethods，we select the entropymethod to rationally determine the indicatorweightand draw on the indicator evaluation system built by predecessors for the comprehensive evaluation and obstacle diagnosis of circular agriculture in Guizhou Province.Guizhou Province is a traditional agricultural province，and agriculture has a large share in the industrial structure.In the context of carrying out the construction of circular agriculture nationwide，Guizhou Province should rely on these favorable conditions to improve the sustainable developmentof agricultural system and social，economic and ecological benefits in Guizhou Province.By selecting Guizhou Province as the object of empirical research，this paper builds the indicator system for the comprehensive evaluation of circular agriculture，and analyzes the obstacles to the development of circular agriculture，in order to provide a reference for the further developmentof circular agriculture in Guizhou Province.

2 The basic content of comprehensive evaluation indicator system for the development of circular agriculture in Guizhou Province

2.1 Design of com prehensive evaluation indicator system for the development of agricultural circular economyIn building the evaluation indicator system for the development of agricultural circular economy，this paper drawson the BPEIR conceptualmodel of Ma Qifang et al.，namely＂Behavior-Pressure-Effects-Impact-Response＂model.The evaluation indicators include four aspects：economic and social development indicators；resources reduction input indicators；resources recycling evaluation indicators；resources and environment safety evaluation indicators［8］.In this paper，based on the actual situation of agricultural development in Guizhou Province and principle of circular agricultural development，we select 15 factors as the evaluation indicators，to build the comprehensive evaluation indicator system for the development of circular agriculture in Guizhou Province.

2.2 Establishment of comprehensive evaluation indicator system for the development of circular agriculture

2.2.1Data sources.The economic data aremainly from Guizhou Statistical Yearbook（2003-2012），China Statistical Yearbook（2003-2012），Guizhou Provincial Economic and Social Development Statistics Bulletin（2003-2012）.The relevant resources data aremainly from Guizhou Provincial Land and Resources Bulletin（2003-2012）and the relevant governmentwebsites.

2.2.2The basic principles and calculation steps of entropy method.In information theory，there is a function relationship H（x）＝-∑f（XK）ln f（XK），where H（x）is information entropy and-∑f（XK）ln f（XK）is information，with opposite signs but same absolute value.Entropy isameasure ofuncertainty.The larger the amount of information，the smaller the uncertainty，and the smaller the entropy；the smaller the amountof information，the greater the uncertainty，and the greater the entropy.Assuming there are m years and n indicators，it can form an original data matrix X＝（Xij）mn.According to the characteristics of entropy，we can use the entropy value to judge the degree of dispersion of indicator Xj.If there is greater difference in the indicator value Xij，then the degree of dispersion of Xjwill be higher，and H（x）will be smaller，that is，the amountof information provided willbe larger and theweightwill also be greater.Therefore，based on the degree of dispersion of indicators，we can use the relationship between the raw data to determine the indicator weight.

（i）There are positive and negative indicators in the evaluation indicator system for the development of circular agriculture.The greater the value of positive indicators，the better the development of circular agriculture；if the value of negative indicators is smaller，itwill bemore conducive to the development of circular agriculture.So it is necessary to adopt different algorithm for the standardization of positive and negative indicators：

where Xijis the value of evaluation indicator j in year i；max｛Xj｝and min｛Xj｝are themaximum andminimum values of evaluation indicator j in all years，respectively；m is the number ofevaluation years；n is the number of evaluation indicators.

（ii）Calculate the proportion of value of indicator j in year i：

（iii）Information entropy is an indicator to measure uncertainty.In the multi-attribute decision making，various column vectors of normalized decision-making matrix X［（X1j，X2j，…，Xmj）T，（j＝1，2，…，n）］are seen as the distribution ofamountof information to calculate the entropy of indicator property Xjas follows：

（iv）Calculate the coefficient of variation of indicator j，namely the discrimination degree for the evaluation degree（dj）：

（v）Calculate theweightof each property Xj，and the higher the coefficient of variation，the greater theweight Wj：

2.2.3Indicator weight determining.Therefore，according to the basic principles and calculation steps of the above entropy method，we get the comprehensive evaluation indicator system for the development of circular agriculture in Guizhou Province aswell as indicatorweight（Table 1）.

Table 1 Comprehensive evaluation indicator system for the development of circular agriculture in Guizhou Province

3 Empirical analysis

3.1 Comprehensive evaluation resultsThe evaluation score of single indicator is calculated as follows：

Since the evaluation of developmentof agricultural circular economy is comprehensive evaluation，the weighted function method is used to calculate the composite score of circular agriculture in a year：

where Wjis theweight of various indicators；X′ijis the normalized value for each evaluation indicator；S is the comprehensive evaluation score of development of circular agriculture.

The comprehensive evaluation results of circular agriculture in Guizhou Province can be calculated as shown in Fig.1.According to Fig.1，the development process of circular agriculture in Guizhou Province during 2003-2012 can be divided into three phases.（i）The phase of slow ascension（2003-2005）.During this phase，the evaluation value of circular agriculture was higher than in 2003，the comprehensive evaluation value was in（0.27，0.37），and the average annual growth rate of comprehensive evaluation value of circular agriculture reached 18.5%.（ii）The phase of small decline（2005-2006）.The comprehensive evaluation value of circular agriculture was 0.376 in 2005 and 0.3 in 2006，decreasing by approximately19%.（iii）The phase of rapid development（2006-2012）.Compared with 2003，the development level of circular agriculturewas rapidly enhanced，and it increased from 0.3 in 2006 to 0.767 in 2012，an increase of about 26%.

The changes in the evaluation index of various classification indicators concerning the development of circular agriculture in Guizhou Province during 2003-2012 can be shown in Fig.2.In terms of the annualaverage index value of various classification indicators concerning the developmentof circular agriculture，it is in the descending order as follows：economic and social development indicator（1.452），resource and environment safety indicator（0.327），resource reduction input indicator（0.299），and resource recycling indicator（0.117）.（i）From the analysis，it is found that the evaluation index of economic and social development indicator showed an overall upward trend，and the economic and social development indicators are positive indicators，indicating that the economic and social development factors have played an important role in enhancing the overall development level of circular agriculture in Guizhou Province since 2003.But therewas great volatility in the evaluation index of economic and social development indicator，undergoing two phasesofdecline in 2003 and 2012，suggesting that the economic and social development in the two phases has become the obstacle to the development of circular agriculture in Guizhou Province.（ii）After 2003，the evaluation index of resource reduction input indicator showed an overall downward trend.During 2003-2008，the resource reduction input index declined ceaselessly，indicating that the main limiting factorwas resource reduction input.During 2008-2010，the resource reduction input index climbed，indicating that the constraint of resource reduction input on circular agriculture was eased.During 2010-2012，the resource reduction input index showed a downward trend again，indicating that there was a phenomenon of high resource input in the development of circular agriculture.（iii）The resource recycling index after2003 washigher than in 2003 except2006，and the resource recycling index from 2003 to2012 showed a rising overall trend.The resource recycling levels in Guizhou Province havemade important contribution to the development of circular agriculture.（iv）The evaluation index of resources and environment safety indicators after 2003 showed an upward trend overall.During 2003-2012，the index of resources and environment safety indicators showed a rising trend except 2004，indicating that the development of agriculture in Guizhou Province during this period focused on the environmental protection and resource conservation，in favor of development of circular agriculture.

3.2 Obstacles to the development of circular agriculture

We can use three indicators（factor contribution degree，indicator deviation degree and obstacle degree）to judge the constraints on the development of circular agriculture.The factor contribution degree Ujis the weight of various indicators in the comprehensive evaluation indicator system，as shown in Table 1.The indicator deviation degree Vjrepresents the gap between the individual indicators and development goals of circular agriculture，denoted by the difference between normalized value of single indicators and 100%.The obstacle degree Wjsignifies the value of influence of individual indicators and classification indicators on the overall level of circular agriculture，and this indicator is the result and goal of obstacle diagnosis of circular agriculture.The indicator principle and calculationmethod are as follows［9］：

where Xjis the normalized value of individual indicators，and the value is derived using the extreme value normalization.

Through the ranking of obstacle degree（Mj）of individual indicators，we can determine the degree of influence of various obstacles to the development of circular agriculture.We perform the individual indicator obstacle degree test on the development level of circular agriculture in Guizhou Province in 2012 and sequence themajor obstacles，as shown in Table 2.

Themajor obstacles to the developmentof circular agriculture in Guizhou Province in 2012 are sequenced in descending order in terms of the individual indicator obstacle degree as follows：application rate of chemical fertilizer＞pesticide use levels＞plastic sheeting use levels＞commodity rate of farming，forestry，animal husbandry and fishery＞grain yield＞per capita food output＞per capita arable land area.It can be found that themajor obstacles to the developmentof circular agriculture are focused on the resource reduction input indicators and economic and social development indicators.In order tomore clearly determine the obstacles to the development of circular agriculture，we calculate the obstacle degree of four classification indicators for the evaluation on development of circular agriculture，respectively，and the specific results are shown in Fig.3.It is found that the obstacles to the development of circular agriculture in Guizhou Province in 2012 are resource reduction input indicator（77.74%），economic and social development indicator（21.23%），and resourcesand environment safety indicator（1.03%）.And the obstacle degree of resource recycling indicator is0，indicating that the developmentof circular agriculture is not restricted in terms of resource recycling.Therefore，under the current conditions for agricultural development，how to improve the efficiency of resources inputbecomes a prominent issue in Guizhou Province.

Table 2 Ranking ofmajor obstacles to the development of circular agriculture in Guizhou Province in 2012

4 Conclusions and policy recommendations

4.1 ConclusionsVigorously developing agricultural circular economy is an effectiveway to achieve sustainable agricultural development，and a strategic measure to ease the pressure on agricultural resources，protect ecological and clean resources，and promote sustainable agricultural and rural economic development.By analyzing the obstacles of various indicators and four classification indicators in 2012，it is found that the resource reduction input has become the biggest obstacle to the development of circular agriculture，followed by the level of economic and social development.The application rate of chemical fertilizers，pesticide use levels and plastic sheeting use levels are the major obstacles.Three economic and social development indicators（commodity rate of farming，forestry，animal husbandry and fishery，grain yield and per capita food production）also severely limit the development of circular agriculture，indicating that the agricultural output is low and the commodity rate of agricultural products is also low in Guizhou Province.Meanwhile，the per capita arable land area also affects the safety of resources and environment to some extent.Therefore，in the future development of circular agriculture，it is necessary to take appropriatemeasures to focus on improving the resource input efficiency and socio-economic development.

4.2 Policy recommendations

4.2.1Reducing thematerial inputs per unit area and improving the resource utilization rate.Atpresent，the resource reduction input has become amajor factor limiting the development of circular agriculture in Guizhou Province，so it is necessary to solve some problems during agricultural production，such as excessive use of chemical fertilizers，pesticides and plastic sheeting aswell as pollution caused by the use of these resources.First，it is necessary to use scientificmethods to allocate fertilizersand pesticides in accordance with the scientific proportion，and try to use low toxicity and residue pesticides and organic fertilizers to improve the efficient use of fertilizers and pesticides.Second，it is necessary to solve the problem of land pollution caused by plastic sheeting and improve the reuse of plastic sheeting to reducewaste and pollution of plastic sheeting.

4.2.2Promoting the agricultural industrialization and improving the commodity rate of farming，forestry，animal husbandry and fishery.The commodity rate of farming，forestry，animal husbandry and fishery in Guizhou Province limits the developmentof circular agriculture，so it is necessary to actively promote the agricultural industrialization，extend the industrial chain of agricultural production，and focus on the development of agro-processing industries.Guizhou Province should seize the opportunity to play its own comparative advantages to develop cash crops and livestock industries；develop new circular agriculture and three-dimensional agriculture，extend the industrial chain and increase multiple cropping index［10］； actively foster the leading enterprises，strengthen ties with farmers，and establish agricultural cooperatives to raise the level of agricultural industrialization.

4.2.3Strengthening the science and technology input and developing new varieties.Guizhou is a traditional agricultural province，but it has no good arable land resources for agricultural production，so the food production is not high，serious impeding the development of circular agriculture.Therefore，it is necessary to strengthen science and technology input，promote agricultural production technology，actively cultivate new varieties，and convert the scientific and technological achievements into the actual agricultural production.It is necessary to introduce improved varieties ofmajor food crops，increase improved variety coverage，build the high-quality crop variety demonstration area，and build the improved variety breeding base ofmajor food crops.

4.2.4Strengthening the protection of farmland and achieving the food supply and demand balance.Due to limited arable land resources in Guizhou Province，the government should take various measures to implement themost stringent farmland protection system to protectarable land and stabilize the basic farmland area，in order to achieve sustainable use of farmland resources.Meanwhile，in order to alleviate the reduction of arable land and ease the contradiction between human and land，it is necessary to strictly control unlawful appropriation of arable land，actively promote the balance of occupation and compensation of arable land，and steadily increase arable land area to increase food production in Guizhou Province.

4.2.5Strengthening the macro-control and developing the regional development planning of circular agriculture.Government should strengthenmacro-control，to provide policy support for the development of circular agriculture.For example，the government can reward the companies and individuals formaking contribution to the construction of circular agriculture and collect related fees and taxes due to excessive application of fertilizers or pesticides to guide farmers to develop circular economy［11］.Meanwhile，in order to better carry out the construction of circular agriculture，the government should develop regional development planning of circular agriculture tomake comprehensive and accurate deployment for the development of circular agriculture.

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