Fangying ZHOU，Shunqiang SUN*，Joseph J.Molnar

1.Southwest University，Chongqing 400715，China；2.College of Agriculture，Auburn University，AL 36849，U.S.

1 Introduction

Circular agriculture，as a new model of agricultural economic development，combines the theory of circular economic cycle with the theory of sustainable development.It adheres to＂3R principles＂（reduce，recycle and reuse），and includes the economic system into the natural ecosystem，so it is conducive to improving resource utilization efficiency，upgrading industrial structure and achieving harmonious development between man and nature［1］.In recent years，the development of circular agriculture has caused a great buzz.Sichuan is a major agricultural province，where the building of circular agriculture has also attracted the attention of many scholars.There are many studies on the development model of circular agriculture in Sichuan Province at home.Some scholars believe that Sichuan Province can take advantage of resources in different regions to adopt three development models（＂farmer+biog as＂；＂rural cooperative organization+integrated utilization of agricultural internal resources＂；＂agribusiness+non-agricultural use of agricultural resources and agricultural use of non-agricultural resources＂）［2］.Some scholars believe that Sichuan can use the biog as resources to promote three models of circular agriculture（＂pig-biogas-grain＂；＂pig（cattle，sheep）-biogas-mushroom（fruit，mulberry）；＂pig-biogas-vegetable＂［3］.Some have probed into the obstacles to the development of circular agriculture in Sichuan Province，including ecological damage，technological backwardness，and lack of funds［4-5］.Some scholars use DEA method and entropy method to study the effects of the implementation of circular agriculture in some areas of Sichuan to find solutions to improving production efficiency［6］.In summary，the studies with regard to circular agriculture mainly focus on the main features，obstacles and development models concerning circular agriculture，and the effect of implementation of circular agriculture is seldom evaluated，not to mention the literature which studies the contribution of various factors to circular agriculture through objective weighting method.In order to better study the circular agriculture from quantitative and qualitative point of view，this paper selects Sichuan Province as a sample to analyze the current development of circular agriculture，explore the obstacles to the development of circular agriculture，and put forth the policy recommendations for the development of circular agriculture in Sichuan Province.

2 Building of evaluation indicator system for circular agriculture in Sichuan Province

2.1 Design of evaluation indicator system for circular agricultureBased on the evaluation of the development of circular agriculture in Shanghai farm［7］and BPEIR conceptual model developed by Ma Qifanget al.，this paper build the evaluation indicator system for circular agriculture in Sichuan Province in accordance with the actual situation of Sichuan Province from 5 integrated indicators and 11 specific indicators，in order to understand the status of the development of the circular agriculture in Sichuan Province and provide policy recommendations for the development of circular agriculture（Table 1）.

2.2 Evaluation methods for current development of circular agriculture

2.2.1 Data sources.The economic data are mainly fromSichuan Provincial Economic and Social Development Statistics Bulletin（2000-2012），and the relevant policies aremainly from the Sichuan Provincial People's Government website.

2.2.2 The basic principles of the coefficient of variation and calculation steps.To reduce the drawbacks of subjectivity in weighting，this paper uses the objective weighting method-coefficient of variation to determine the weight of evaluation system.In the multi-indicator evaluation，if there is great variation in the ob-served values of all evaluation objects for an indicator，it indicates that the evaluation objects will be difficult to reach the average of indicators，and there will be greater ability to clearly distinguish between various evaluation objects，so it should give greater weight；on the contrary，it should give less weight［8］.

Table 1 The evaluation indicator system for circular agriculture in Sichuan Province

Use the maximum difference normalization method for normalizationYij：

Calculate the average of indicatorsYj：

Calculate the standard deviation of indicatorsSj：

Calculate the coefficient of variation of indicatorsVj：

Calculate the weight of indicatorsWj：

Calculate the overall index score of the evaluation objectFi：

The results are shown in Table 2.

酪蛋白蛋白質(zhì)組學(xué)研究主要包括酪蛋白種類與異構(gòu)體分析及磷酸化研究幾個方面。2004年，Holland等[13]利用二維聚丙烯酰胺凝膠電泳技術(shù)發(fā)現(xiàn)了10種κ-酪蛋白的異構(gòu)體。Ciavardelli等[14] 利用電感耦合等離子體質(zhì)譜法檢測出牛乳中α-酪蛋白和β-酪蛋白磷酸化位點(diǎn)，使酪蛋白的磷酸化逐漸成為研究酪蛋白蛋白質(zhì)組學(xué)的研究重點(diǎn)[15]。

Table 2 Calculation results of evaluation indicators for circular agriculture in Sichuan Province

3 Analysis of results based on the evaluation system for circular agriculture

3.1 Analysis of comprehensive evaluation resultsSichuan Province is located in the upper reaches of the Yangtze River and the southwestern part of China，with complex terrain.It can be divided into the Sichuan Basin and West Sichuan Plateau.The annual average temperature is high and the frost-free period is long.The province's climate type is complex.The eastern part featuresa humid subtropical climate while the western part has a vertical mountain climate.The diverse climate types are suitable for the diversified agricultural operation.Using the above methods，we get the comprehensive evaluation results on the evaluation system for circular agriculture in Sichuan Province（Fig.1）.As can be seen from Fig.1，from 2000 to2012，the level of circular agriculture in Sichuan Province rose continuously.This period can be divided into three stages.（i）2000-2003（stable development stage）.At this stage，each indicator remained at around 0.15，and there was little change in the level of the development of circular agriculture.（ii）2003-2008（rapid development stage）.During this period，the circular agriculture achieved remarkable results，and the value of various indicators was high，with the average annual growth rate of 1.23.（iii）2008-2012（fluctuating development stage）.At this stage，the comprehensive evaluation indicator value rose in fluctuations，with the average annual growth rate of1.13.

To further analyze the current situation of circular agriculture in Sichuan Province，this paper draws the indicator values into a line chart，as shown in Fig.2.From 2000 to 2012，the level of agricultural production showed a stable upward trend，with the average annual growth rate of0.51.From 2005 to2010，the value of this indicator was higher than that of other indicators，but after 2010，the value was gradually lower than that of resource reduction input indicators，indicating that in recent years，the level of agricultural production in Sichuan Province has rapidly increased，and the circular agriculture has achieved remarkable results.From 2002 to 2012，the value of resource reduction input indicators showed a dramatic upward trend amid fluctuations，but after2010，the value was higher than that of level of agricultural production.The entire development process can be divided into four stages.（i）2000-2003（stable development stage）.There was little change in the indicator value.（ii）2003-2004（rapid rise stage）.The average annual growth rate was1.43，and the level of circular agriculture was improved rapidly.（iii）2004-2006（slow decline stage）.The development of circular agriculture in Sichuan Province was hampered.（iv）2006-2012（rapid rise stage）.The average annual growth rate was1.19，and especially from 2007 to 2008，the annual growth rate was as high as 1.27.Resource reduction input indicators are the indicators with negative effects，and the smaller the indicator value，the greater the constraints on circular agriculture.In recent years，the value of this indicator has increased rapidly，indicating that the resource input factors play a declining role in restricting the circular agriculture.From 2000 to 2012，the value of resource recycling indicators showed a slow upward trend，but the indicator was overall at the bottom of evaluation indicators，indicating that the resource recycling was always an important factor limiting the development of circular agriculture in Sichuan Province，and there was a need to further improve the level of resource recycling.The environmental building indicators showed a regular change，which can be divided into two stages.（i）2000-2009（stable development stage）.The indicator value remained at around 0.08.（ii）2010-2012（rapid rise stage）.The indicator value reached 0.2624 in 2012，with the average annual growth rate of 1.26.After 2010，Sichuan Province paid more attention to environmental protection while developing circular agriculture，but the overall level was low，indicating that Sichuan should continue to increase environmental protection efforts while developing circular agriculture.

3.2 Analysis of obstacles to the development of circular agricultureOn the basis of evaluation of various indicators，there is a need to analyze various levels of circular agriculture system，identify the obstacles to the sustainable development of circular agriculture and timely adjust the agricultural practices.We use＂factor contribution degree＂，＂indicator deviation degree＂and＂obstacle degree＂to judge.

Factor contribution degreeUjmeans the degree of influence of individual indicators on the overall objective，namely the weight of the indicators in the evaluation system.

whereRjis the weight of classification indicatorj；wijis the weight of single sub-goalithat classification indicatorjbelongs to.

Indicator deviation degreeVjrepresents the gap between the individual indicators and overall goals，and it is denoted by the difference between normalized value of individual indicators and 100%.

Obstacle degreeWjrepresents the value of influence of individual indicators and classification indicators on overall level of goals，and this indicator is the diagnosis result and goal of obstacles to the development of circular agriculture.

Based on the development of circular agriculture in Sichuan Province in 2012，we perform the obstacle degree test on various factors concerning circular agriculture and sequence the obstacle degree.The results are shown in Table 3.

In accordance with the obstacle degree，the major obstacles to circular agriculture in Sichuan Province in 2012 include the number of livestock at the end of year，resource recycling potential，effective irrigation coefficient，and chemical fertilizer application intensity，fertilizer production efficiency and per capita arable land area.The statistics show that the obstacles to circular agriculture in Sichuan Province in 2012 are mainly concentrated in the agricultural production level indicators，resource recycling indicators and environmental building indicators，especially for the agricultural production level indicators and resource recycling indicators at the forefront of obstacle degree，indicating that the ag-ricultural output is still low and the resource use efficiency is low during the development of circular agriculture in Sichuan Province.In order to evaluate the obstacle degree for the development of circular agriculture in Sichuan Province in 2012，we sort the obstacle degree（Bi＝∑Mi，j）concerning four classification indicators of circular agriculture evaluation system in Sichuan Province（Fig.3）.As can be seen from the Fig.3，the obstacle factors influencing the development of circular agriculture in Sichuan Province in 2012 are agricultural production level indicators（0.4070），resource recycling indicators（0.3215），environmental building indicators（0.1976）and resource reduction input indicators（0.0741）.Therefore，in the context of current development of circular agriculture，how to improve resource utilization rate and increase agricultural output while protecting the environment becomes a key factor influencing the further growth of circular agriculture in Sichuan Province.

Table 3 Evaluation results of obstacle degree of various factors concerning circular agriculture

4 The problems in the development of circular agriculture in Sichuan Province

4.1 Low resource recycling rateThe analysis shows that the resource recycling potential has tended to decline in recent years，becoming the obstacle to the further development of circular agriculture in Sichuan Province.The development of circular agriculture in Sichuan Province still faces the problem of low resource recycling rate.The industrial chain within agriculture or between agriculture and other industries is short，and it does not form a closed development model of circular economy.The regional development model is similar，and the regions never consider their own advantages to develop specialized agriculture.The reason is that the industrialization degree of agriculture in Sichuan Province is low，and the agricultural industry chain is short，lacking close contact with other industries；the development of circular agriculture becomes alienated from reality and it has weak competitiveness.

4.2 Poor application effect of chemical fertilizerFrom the above obstacle analysis，we can see that the improper application of chemical fertilizer has become a key factor hindering the development of circular agriculture in Sichuan Province.In recent years，the fertilizer consumption has increased year by year in Sichuan Province.In 2009，the chemical fertilizer consumption（530 kg/hm2）was much higher than the standard of developed countries（225 kg/hm2），and also higher than the national average（330 kg/hm2）.Blind fertilizer application causes serious waste of resources，and causes great harm to the environment.It will not only cause water pollution but also cause soil acidification.

4.3 Weak agricultural output capacityIn recent years，the circular agriculture has developed by leaps and bounds in Sichuan Province，but the overall output level is low.Among four classification indicators，the agricultural production level indicator has the highest obstacle degree，and it does not meet the high-yielding requirements of circular agriculture.From the obstacle analysis of individual indicators in 2012，it is found that the number of livestock at the end of year becomes the primary factor restricting the development of circular agriculture in Sichuan Province.This is related to the infrastructure backwardness in Sichuan Province.Sichuan has poor conditions for agricultural development，and low level of technology，lacking the research，development and application of new varieties and new technologies.A few years ago，there were few national support policies for agriculture in Sichuan and the funds for the development of circular agriculture were short.

4.4 Serious challenges for environmental buildingFrom the individual indicators，we can see that some environmental building indicators such as effective irrigation coefficient and per capita arable land area，have become major obstacles to healthy development of circular agriculture in Sichuan Province.From the classification indicators，we can also find that the environmental building indicators constitute the key factors for sustainable development of circular agriculture in Sichuan Province.Sichuan has a large population，but the arable land is insufficient；with increasing land for construction，the agricultural land problem will become increasingly serious.Traditional agricultural irrigation technology can not meet the needs of circular agriculture，resulting in low efficiency of irrigation，water waste and other agro-ecological problems.

5 Recommendation for the sustainable development of circular agriculture in Sichuan Province

5.1 Extending agricultural industrial chain to promote the industrialization of agricultureAccording to the mode of con-nections between farmers and society，the agricultural industrialization in Sichuan Province can take the following three modes.（i）Market+farmers.The agricultural activities are organized according to the market needs，and the decisive role of market in resource allocation is played.（ii）Leading enterprises+farmers or leading enterprises+intermediary organizations+farmers.The agricultural production is conducted according to the enterprises'operating mode to achieve the integration of production，supply and marketing.（iii）Cooperative organizations+farmers.The cooperative organizations are responsible for providing market information，technology promotion and marketing services，to enhance the specialization of agriculture.The production of competitive industries can be conducted according to the resource endowments of different regions.

5.2 Scientifically using the fertilizer to improve application efficiency（i）It is necessary to actively promote the balanced fertilization technology and use different proportions of nitrogen，phosphorus，potassium and other fertilizers for different crops in different regions，to avoid wasting resources；actively promote organic fertilizer and microbial fertilizer，and use waste composting in the places where conditions permit.（ii）It is necessary to vigorously research and develop the soil fertilization technology，strengthen the study of soil composition in different regions，and provide different standards of organic fertilizer for different types of soil to meet the needs for different soil nutrients.（iii）It is necessary to develop fertilizer-saving technology and reduce the consumption of chemical fertilizer to improve utilization efficiency.

5.3 Improving the agricultural infrastructure and enhancing the development momentum of circular agriculture（i）It is necessary to first improve the level of agricultural mechanization in Sichuan Province.Sichuan Province has large plains and hilly regions，so there is a need to actively introduce advanced large-scale agricultural machinery for large-scale and specialized production.（ii）It is necessary to strengthen the scientific and technological innovation of circular agriculture to promote efficient use of resources.On the one hand，the government should increase support for agricultural science and technology，and provide adequate funding for the agricultural science and technology talent cultivation and agricultural machinery configuration.On the other hand，each region should take the initiative to learn agricultural knowledge to improve scientific literacy of farmers.There is a need to actively promote the cooperation with neighboring universities and research institutions to research and develop the seeds，fertilizers and pesticides suitable for local areas.

5.4 Developing the ecological agriculture and protecting the agricultural environment（i）Sichuan has a large area of mountains and hills，and the ecological environment is fragile，so it is necessary to develop three-dimensional agriculture in accordance with the local conditions in order to protect environment while obtaining high economic value.（ii）It is necessary to protect water resources in the development of the economy；raise the discharge standards of industrial wastewater and domestic sewage；develop water-saving agriculture and use drip irrigation and sprinkler irrigation technologies to reduce the agricultural demand for water.

5.5 Increasing govern ment'spolicy support to boost the development of circular agriculture（i）Local governments should include the construction of circular agriculture into the long-term development plan，develop relevant policies and regulations，establish specialized agencies to coordinate the development of circular agriculture，and increase financial support for the development of circular agriculture.（ii）The government should organize a group of agricultural experts to provide advice and assistance concerning circular agriculture.The agricultural technology is backward in Sichuan，and farmers'education level is generally low，so there is a need to strengthen the training and support for farmers to enable them to adapt to the requirements of modern agricultural development.

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