BoqiWENG，Weili ZHANG，Yixiang WANG

1.Agricultural Ecology Institute of Fujian Academy of Agricultural Sciences，F(xiàn)uzhou 350000，China；2.Agricultural Policy Research Office of Fujian Academy of Agricultural Sciences，F(xiàn)uzhou 350003，China

At present，the agricultural production mode is transforming from traditional to modern agriculture.Circular agriculture，as essence of traditional agriculture，will also inevitably be transformed from traditional production to modern production.Energetically developing modern circular agricultural economy is an inevitable choice for sustainable agricultural development，is important approach of low-carbon economic development，and alsomajor content for promoting scientific development.In the challenge of global climate change，shortage of energy and resources and increasing pressure of ecological environment，it seems particularly urgent and important to develop circular agricultural economy.

1 Current situation of agricultural resources and ecological environment protection of China not optim istic

Since the Eleventh Five-year Plan period，China has made significant achievement in agricultural resources and ecological environment construction，and ecological environment has great improvement.However，the current situation of shortage of biological resources has no change，and the situation of ecological destruction is still serious.We can say that China is still at the primary stage of agricultural resource and ecological environment protection and reasonable use，and current situation of China's agricultural resources and ecological environment is not optimistic.

1.1 Serious shortage of water and soil resourcesChina's per capita farmland is0.092 hm2，which is40%ofworld per capita farmland［1］.In 1997-2007，China's farmland decreased 8.333million hm2［2］.In the total farmland，about 40%is lowyield land，average organicmatter content of farmland has reduced to 1.0%，significantly lower than the level of American-European countries（2.5%-4.0%）［3］.Annual shortage of water for agricultural irrigation isabout30millionm3，about20million hm2farmland suffers from droughts annually on average，and annual drop of crop yield is up to 10-30 billion kg［4］.By 2010，effective use factor of agricultural irrigation water increased to0.5 from 0.4，indicating that about a half water resource iswasted［5］.

1.2 Low use ratio of wastesChina is the largest agricultural waste production country.Every year，the waste production is about4 billion tons，including 2.61 billion tons of livestock and poultrymanure，700 million tons crop straws，100-150 million tons of vegetable wastes，and 37 million m3forest waste（excluding fuel forest），equivalent to10million tons of standard coal［6］.According to prediction，in China's agricultural wastes，crop straws reach 950 million to 1.1 billion tons，and livestock and poultry manure reaches 4.1 billion tons［6］.However，the rate of returning livestock and poultry manure to farmland is only 30%-50%，more than 60%crop straws are not effectively used or returned to farmland，but are burned or stacked anywhere［7］.

1.3 Serious agricultural non-point source pollutionAt present，chemical fertilizer consumption in China has reached 50 million tons with the use rate of about35%，while pesticide consumption reaches1.4million tons with the use rate of about30%.Chemical fertilizer and pesticide not absorbed by crops lead to serious pollution of at least 13-16 million hm2farmland［8］.Soil pollution resulted from pesticide，chemical fertilizer and＂three industrial wastes＂leads to annual decrease of crop yield about10 billion kg；according to estimation of environmental protection department，about 12million tons of grain is polluted by heavy metals annually，leading to directeconomic loss higher than 20 billion yuan［9］.According to statistics of environmental protection department，about 10 million hm2farmland is polluted，accounting for one tenth of total farmland［9］.

1.4 Ecological footprint not optimistic In 2007，the ecologi-cal foot print of human reached 18 billion ghm2，and the ecological footprint per capita was 2.7 ghm2［10］.However，the biological carrying capacity of earth is 11.9 billion ghm2，with biological carrying capacity per capita 1.8 ghm2，whichmeans that the ecological system has overloaded for 50%.In 2007，the per capita ecological footprint of China was 2.2 ghm2，lower than the world average level，ranking the 74th position in the 153 countries calculated［10］.

1.5 Ecological environment still not optimistic

（i）Serious water loss and soil erosion.The second national remote sensing survey indicates thatwater loss and soil erosion area has reached 3.56million km2，accounting for37.1%of thewhole area of China.Every year，the soil loss amount is up to 5 billion tons，and water loss and soil erosion area is equivalent to 9 Japanese area or 35 South Korean area.Sandy land covers 1.74 million km2，and rocky desertification area covers129 600 km2［11］.

（ii）Water environment not optimistic.In 2010，evaluation was carried out forwater quality of176 000 km rivers in the whole country.Results indicate that rivers with Grade Iwater take up 4.8%，rivers with Grade IIwater take up 30%，rivers with Grade III water take up 26.6%，rivers with Grade IV water take up 13.1%，rivers with Grade V water take up 7.8%，and rivers with water worse than Grade V take up 17.7%；evaluation on water quality of 99 lakes shows that lakes with water reaching or better than Grade III water take up 58.9%，lakes with Grade IV and V water take up 27.9%，and lakes with water worse than Grade V take up 13.2%.For trophic status of lakes，there is1 oligotrophic lake，22 mesotrophic lakes，37 light eutrophic lakes，and 28 medium eutrophic lakes.In 2010，total discharge of waste and sewage water was 79.2 billion tons［12］.

（iii）Poor air quality.In 2011，total SO2 emission reached 22.179 million tons，2.21%lower than 2010；total emission of NOx reached 24.043 million tons，5.73%higher than 2010.In 2011，among 468 cities（counties）monitored，227 cities（counties）have suffered from acid rain，accounting for 48.5%；140 cities（counties）have acid rain frequency higher than 25%，accounting for29.9%；44 cities（counties）have acid rain frequency higher than 75%，accounting for 9.4%［13］.

（iv）Area of soil pollution expanded.At present，about 10 million hm2farmland is polluted，accounting for 10%of total farmland.According to estimation，about 12 million tons of grain is polluted by heavy metals annually，leading to direct economic lossmore than 20 billion yuan.Soil pollution leads to accumulation of harmful substance in crops，entry to human body through food chain， leads to various diseases， and finally threatens health［14］.

（v）Biological resources reduced.Rapid economic development increases demands for resources.Unreasonable resource use and huge population pressure present grave threat to biological diversity，leads to reduction or lossof its structure and function，and many species have become endangered species.4 000-5 000 higher plants are threatened，accounting for 15%-20%of total higher plants.In 640 endangered species listed in Convention on International Trade in Endangered Species of Wild Fauna and Flora（CITES），China have 156 species，so the situation is severe［15］.

（vi）Urban and rural rubbish sharply increased.At present，the annual urban rubbish production in China has reached 150 million tons，which is increasing at annual rate of9%.Untreated rubbish reaches 7 billion tons，occupies more than 800 million square meters land，and about 56 million tons of rubbishes are piled in the open annually［16］，so the rubbish has become a big problem in urban governance.

（viii）Uneven forest vegetation.China's forest coverage is only 2／3 of the world average level and ranks the 139th position.The forest area per capita of China is0.145 hm2，less than 1／4 of world value；the forest stock volume per capita of China is10.151 m3，only 1／7 of theworld value［17］.To protectecological environment，we must adhere to sustainable development and explore green energy road.

1.6 Increasing significant global climate changeIn 2007，the Intergovernmental Panel on Climate Change（IPCC）officially issued the Fourth Assessment Report which clearly stated that emission of greenhouse gases due to human activities is the major reason for global warming.In future 100 years，human will still discharge greenhouse gases.In this situation，whether land ecosystem can continue absorb CO2in air，whether it reaches carbon saturation，and when it reaches carbon saturation，are essential problems concerning future earth environment and social economic development.Climate change damages ecological environment，changes stable structure of agricultural production，and increases cost for agricultural production.

2 Low carbon concept and new opportunity for circular agricultural development

2.1 Circular agriculture is an inevitable choice for sustainable development of agricultureCircular agriculture is a brand-new concept and strategy，is a new approach for coordinated develop ment of population，resource，and environment，a new method for promoting agricultural economic growth.Its core idea is to adjust and optimize internal structure and industrial structure，extend industrial chain，increase multiple-level circular use of matter energy of agricultural system，and maximally use agricultural biomass energy resources using sustainable development concept，circular economy theory and industrial chain extension concept through agricultural technological innovation［18］.

Practice has shown that apart from general rules of circular economy，circular agriculture also has several unique characteristics：（i）orderly food chain；（ii）dynamic green production；（iii）clean consumption returning to nature；（iv）proper process favorable for cleaning；（v）wide application field；（vi）win-win cleaningmeasure［19］.

Obviously，production idea of traditional industrial economy is to develop and use natural resources and obtain profit to the maximum extent.In comparison，circular agriculture attaches importance to ecological balance to realize sustainability of resource use rather than taking it as a place for fetching materials，and not deeming it as us able resources.Thus，to keep benign cycle of ecosystem，agricultural production should not only consider its ability of developing nature，but also should fully consider its ability of restoring ecosystem.On the basis of circular economy theory and through design and manage ment of agricultural ecological economic system，circular agriculture is to maximize natural resource use，minimize input of purchasing resources，circulate renewable resources，and reduce harmful pollutant，use natural resources and environmental capacity in environ ment-friendly mode，and to realize ecological transformation of agricultural economic activities.In the production，it is required to use renewable resources to replace non-renewable resources，such as solar energy，wind energy，and farm manure，and setup production on the basis of natural ecological cycle.In agricultural crop system，it is required to promote various agricultural resources to participate high-efficient flow activities in many times，to realize energy conservation，emission reduction and income increase，and promote sustainable development of modern agriculture and rural areas.In essence，circular agriculture is a new low-input，high-cycle，high-efficiency，high-technology，industrialized and dynamic agriculture，and really realizing unity of society，economy and ecology.It is believed that developing circular agriculture is an utmost innovation measure and inevitable choice for tackling future agricultural challenge，and realizing sustainable development of agriculture.

2.2 Circular agriculture is effective approach for low-carbon economic developmentLow carbon economy is economic mode based on low energy consumption，low pollution and low emission，and it is considerable progress of human society after agricultural civilization and industrial civilization.The essence of low carbon economy is high efficient use of energy，clean energy development，and green GDP，and the core is fundamental change of energy technology，innovation of emission reduction technology，innovation of industrial structure and system，and human survival and development ideas.According researches，agricultural land discharges great amount of greenhouse gases，30%higher than total emission of global greenhouse gas，equivalent to 15 billion tons.In China，to tale mission of agricultural greenhouse gases accounts for about17%of total emission of greenhouse gases in the whole country［20］.According to estimation，the emission of agricultural greenhouse gases in 2015 will be48%higher than that in 1994；CH4emission of animal husbandry and N2O emission of farmland are major factors，which will increase 73%and 53%compared with 1994 respectively［21］.

（i）Basic starting point of cir cularagri culture and low carbon economy is consistent.Low carbon economy isa new economic development idea advocated for dealing with global climate changes.With central ideas of low consumption，low emission and low pollution，low carbon economy receives wide concern in the world.Circular economic theory is earlier than low carbon economy，and its core idea is changing traditional＂resource-product-waste＂production system，and realizing＂resource-product-waste resource regeneration use-recycling use＂production system［22］.Experts believe that starting point of circular agriculture and low carbon economy is consistent，both stress changesof traditional in dustrial mode and living mode，caring about environ mental protection and resource conservation.

（ii）Circular agriculture is the best manifestation of low carbon economy in agricultural field.To develop circular agriculture，it is required to realize fundamental change of high carbon economy to low carbon economy.Modern circular agriculture follows4R principle，namely，＂reduce，reuse，recycle and regulate＂.Through reasonable design and optimum distribution，it forms circular chain，makes waste of this level become material of the next production process，to realize low exploration，high-efficient use，low emission，recycle，and reduce carbon emission.Through scientific research and reasonable distribution，the modern circular agriculture can use materials and energy to the maximum extent，effectively prevent and control entry of harmful substancesor unfavorable factors into the circular chain，improve quality and benefit of agricultural development，realize coordination between economic development，resource conservation and environmental protection.

（iii）Circular agriculture is effective carrier of low-carbon economic development.Sustainable development must transform productionmode through innovation and breakthrough in agricultural science and technology，to realize comprehensive benefits of high output，high quality，high efficiency，safety and ecology.Circular agriculture is a brand-new economic development mode based on circular economic theory，organizes agricultural production using scientific and technological achievements and modern management methods，and realizing organic integration of agricultural resources，environment and economy，benign cycle and sustainable development.As an environment-friendly agricultural mode，its orderly operation，optimal mode and efficiency of emission reduction make it become effective carrier for developing low carbon economy and have high social，economic and ecological benefits.Practice has proved that developing circular agriculture is an important approach for energy conservation and emission reduction for agriculture and promoting development of low carbon agriculture.

3 Analysis on typical circular agriculture mode and benefit

On the basis of stressing and implementing4R principle，southeast regions of China have explored several new characteristic and individualized circular agricultural development modes in accordance with local realities.These typical and mature modes will provide favorable reference for developing circular agricultural economy，promoting circular use or rural resources，and promoting sustainable development of modern agriculture.

3.1 Ecological orchard in hilly areasBased on ecology theo-ry and systematic engineering method，this mode is to realize high efficiency and low consumption and establish benign cycle production system in certain hilly area on the＂integrated，coordinated，circular，and renewable＂principles，through scientific distributing forest，fruit，grass，animal husbandry，fishery and edible fungus production，integrating prevention and control of water loss and soil erosion，developing marsh gas energy，comprehensively use grazing，marsh gas dregs and excrement of livestock，improving soil and fostering and applying land fertility.Planting high quality forage grass in orchard can reduce ground exposure，reduce water loss and soil erosion，increase land use and improve soil fertility.In July，it can reduce ground surface temperature as high as 4.7-5.2℃，increase water content in soil as high as（40-60 cm）3.70%-8.48%，and increase organic matter in soil up to 0.55%.

Take Jiang kou Town model orchard of Jianyang City in north Fujianmountain areas as an example，planting forage grass in orchard reduces application of fertilizer and pesticide，and increase yield and quality of fruit（single fruit tree can increase income of 10.8 yuan）.Grass intake of first born milk cow is18 798 kg，milk output of each cow reaches3 036 kg，and out putvalue of each cow is 4 857 yuan，so each cow can earn 800 yuan.Besides，it also can provide barnyard manure up to 4 453 kg for cultivation of edible fungus and high quality organic manure of orchard.Calculated with grass yield of planting grass in orchard，about0.7-0.8 hm2forage grass can satisfy demand of amilk cow，which can save cost of 762 yuan annually［23］.In addition，using extra forage grass，straws and manure，it can develop marsh gas，increase cycle process，and reach themultiple purpose of forage grass.According to estimation，an 8-10 m3marsh gas pool can save 1.5 tons of faggots annually，equivalent to annual growth of0.13-0.2 hm2firewood trees.After the forage grass is fermented in marsh gas pool，it can recover 90%energy，and also it can produce high quality efficient organic fertilizer.

3.2 Sightseeing ecological agricultural gardenSightseeing ecological agriculture，relying on rural resources，based on agricultural operation，is a new green rising industry integrating primary，secondary and tertiary industries.In production agronomy，sightseeing ecological agriculture attaches importance to combination ofmodern high science and technology and traditional intensive and meticulous farming，and regulating production in accordancewith green standard；in production mode，itvalues characteristics of different species and takes vertical reasonable and beautiful structure with rich connotation.Sightseeing ecological agricultural garden mode is China's ecological agricultural theoretical and technological system guided by＂integrated，coordinated，circular and renewable＂principle，haswide biodiversity，industrial complexity，ecological optimization，and beautiful environment，and is excellent carrier of rural construction and sightseeing agriculture.The sightseeing ecological agriculture extends food nutritional function and industrial raw material function，promotes increase in far mers'income，and expands employment of farmers，further extends to low carbon，ecological protection，sightseeing tourism，and cultural inheritance functions，and realizes integration of production，living and ecological functions.

Take Longjia ecological mountain villa in Longhai of Zhangzhou City as an example，the villa covers an area of 66.7 hm2，and includes ecological tourist zone，ecological agricultural model zone，water aquaculture and water recreation alzone，resort service zone，recreational and sports zone，and Fujian and Taiwan high efficient agricultural research institute.It can produce fruit（longan，Litchichinensis，and banana，etc），livestock（pig），poultry（chicken，duck，and goose），and fresh-water dishes.In 2004，aquaculture income took up more than 90%of total income of the ecological agricultural garden；annual output value reached 1.151 million yuan，and the profit reached 160 000 million yuan，and the profit rate reached 13.9%；it built many types of ecosystem，such as mountain，water，farmland，forest，and road，and improved natural and agricultural ecological environment of the project area.For example，construction of ecological orchard plays a significant role in improving micro-ecology，preventing water loss and soil erosion，cultivating soil fertility，forming＂fruit-grassanimal husbandry-marsh gas＂ecological circular system，and reducing agricultural pollution.Annually，it can provide 33.3 tons，marsh gas dregs，241 tons of marsh liquid，4500 m3marsh gas，and save cost of 67 500 yuan.In 1999-2004，only in stone waste，Longjia garden reduced input of 3.6 million tons，saved 800 000 yuan for treating waste，and it saved 500-600 kg leftovers daily for raising chicken and saving 60-80%feeds.

3.3 Crop straw useIn southeast China，rice cultivation is wide，rice straws are surplus and the use ratio is relatively low，and economic benefit is low.In line with these realities and development of rural fungus industry，through fermentation of rice straws，cultivation and management of high quality and high yield rice，and recycling use of fungus residue，southeast regions have built the crop straw recycling use mode and technological system with fungus industry as the core and rice as major crop.Take＂rice straw-edible fungus-fungus residue-organic fertilizer＂recycling usemode asan example，fungus residue can bemade into different types of special or compound organic fertilizer through processing，and such process is gradually mature at present.Researches show that high temperature cellulose fungus can increase temperature of fungus residue to 45℃above and lasts for 18-20 days.With composting of45 days，all technical indicators of inoculated fungus residue reach standards of organic fertilizer（NY525-2002）［24］.

With constant improvement in process and technology for making organic fertilizer with fungus residue，the＂straw-edible fungus-organic fertilizer-planting industry＂recycling agricultural development mode will have a brighter application future.According to estimation，cultivating straw-based fungus in one hectare can increase yield and income up to 1 500 yuan.Compared with imported compound fertilizer，it can save chemical fertilizer cost up to 300 yuan for one hectare，producing organic fer-tilizerwith fungus residue can realize profitof60 yuan forone ton，and such organic fertilizer can replace 30%chemical fertilizer.Straw-based edible fungus recycling agriculture features combining straw use，edible fungus cultivation，livestock industry，nuisanceless planting，and clean energy production，taking straw as starting point of edible fungus cultivation，extending industrial chain through subsequent development and use of fungus residue，increasing added value of straw-based fungus industry，and realizing organic integration of economy and ecology.

3.4 Use of stock farm manureUsing basic principles of ecological economy，circular economy and systematic science，taking ecological engineering method，and combining corresponding animal，plant，and microorganism，this mode forms a benign low consumption food chain production process system.It can not only reasonably and effectively develop and usemany types of natural resources，covert low-value natural resources to high-value livestock products，but also prevent and control pollution of rural environment，and realize stable，high-efficient and sustainable development of economic，ecological and social benefits.Take an example of pig farm manure sewage control of Xingyuan Agriculture and Animal Husbandry Development Company in Fuqing City.According to estimation of experts，using pigmanure to replace 20%cow manure and cultivate 6 000 m2mushroom，it can reduce cow manure input up to 10 tons；usingmarsh liquid to apply fertilizer36 hm2，it can save fertilizer input（converted to pure N，P，K）about27 tons；usingmarsh gas to generate electricity，it can save electricity 182 500 kWh annually；using pigmanure to produce organic fertilizer，it can save raw material input up to 1 000 tons and save raw material cost up to 373 500 yuan annually，showing considerable economic benefit.In ecological benefit，it builds pigmanure sewage recycling project，realizes multiple level recycle of manure sewage，annually absorbs manure sewage up to 21 600m3，annually cleans manure sewage about33 000m3，realizes recycle of wastewater for flushing pig pens，and saves water resource more than 30 000 tons.Thus，it not only solves environment pollution resulted from manure，but also saves consumption of water，electricity and fertilizer，showing enormous ecological benefit.

4 Countermeasures for further developing circular agriculture

4.1 Integrally building system and setting up suitable mode

（i）Integrally building system.It is recommended to fully push forward development of conservation-oriented society and construction of new socialist countryside and promote sustainable development of agriculture and rural consumption with concept of circular economy as guidance.Besides，it should make integral plan for agricultural and rural industry，rural production and living，and rural community construction and urbanization development in accordance with＂harmless，low-emission，zero damage，high-efficiency，and sustainable＂ideas，and start with developing resource conservation-oriented agriculture，clean production in agricultural industrial process，recycling use of agricultural waste，and clean production of rural living，to promote reform of agricultural technical patterns and organizational form，and building circular rural economic system.

（ii）Setting upmodes suitable for local conditions.On the basis of specific advantages of differentmodes，it should make proper distribution and structural adjustment，extend industrial chain，optimize cycle process，and promote healthy，safe and orderly production of circular agriculture.Also，itmay set up a series of suitable modes，such as vertical cultivation and breeding mode，agricultural and animal husbandry combined mode，circular fisherymode，river basin comprehensive control mode，facility ecological agricultural mode，and sightseeing ecological agricultural mode，to increase far mers'income，raising resource utilization ratio，and improve agricultural production and rural living environment.

4.2 Establishing production standard to ensure food safety

（i）Producing high quality agricultural products in environmentfriendly and ecological manner.It is required to reduce use of chemical compound，and use more organic fertilizer.Production should be conducted in accordance with appropriate standards，namely，complying with＂integrated，simplified，coordinated and optimum＂principles，to promote clean production，conservationoriented production and safe production of agricultural products，accelerate the process of agricultural standardization，and reinforce quality assurance system of green products.

（ii）Realizing nuisanceless production through implementing standards.It is recommended to formulate standards for use of means of agricultural production，including requirements for environment of raw material producing area of agricultural products，use of fertilizer and pesticide，and prevention and control of plant diseases and insect pests，reduce excessive input of chemical fertilizer，and adjust，optimize and upgrade rural industrial structure.

（iii）Realizing high benefit of circularagricul ture through industrialized operation.On the precondition of complying ecological principle，it should make overall arrangement and organization of relatively independent production systems in the form of industrialized operation，realize integrated and coordinated in dustrialoperation，such as integrated distribution，integrated type，integrated farming，integrated process，integrated sales，and integrated settlement，and take the development road of＂small group-large scale，small peasant-large base＂，so as to guarantee production scale and quality of green agricultural products，and realize benign cycle of economic and ecological operation.

4.3 Increasing technological innovation to support sustainable development

（i）Researching and developing low-emission technology in combination with production realities.Development of circular agriculture is not equal to free from resource consumption，it still needs resource input，but it is required to follow the principle of proper amount.Proper amount means reasonably reducing use of chemi-cal fertilizer and pesticide and increasing utilization ratio，which is core part of circular agriculture.Besides，it is recommended to further enhance research and develo pmentof precision agricultural technologies，and make breakthrough in precision sowing，precision fertilizer application，precision irrigation，and precision harvesting［25］.

（ii）Developing green production and waste recycling technology.Wastes are also resources.Thus，it is possible to recycle wastes using proper technologies，such as rice husk and corncob recycling technology，medium density straw plywood processing technology，crop straw granulating technology，soil formula testing and precision fertilizer application technology，comprehensive prevention and control technology of plant diseases and insect pests，and rural new energy development and energy saving technology.

（iii）Giving prominence to industrial advantages and innovating upon applicable coupling technology.It is required to enhance innovation and breakthrough in coupling technologies，such as coupling of processes of circular production，match of straw feed with suitable animals，suitable quantity and breeding method，match of marsh gas fertilizer and crop nutrient demand and application time.

4.4 Innovating upon system and mechanism to promote industrial development

（i）Innovating upon mechanism to promote sustainable development.Developing circular agriculture not only needs technological innovation，but also needs a complete set of diversified input mechanism.It is proposed to bring into full play fundamental function of market allocating resources，and stimulate enthusiasm of all relevant parties for developing circular economy.Through establishing market trading system and charging system，it is expected to make enterprises become real entities of developing circular economy.At the same time，it is required to introduce many investment entities to realize diversified investment entities.

（ii）Making overall plan to explore industrial development mode.On the whole，it should take developing industrial chain of urban and rural areas and different fields as objectives，to explore and set up＂ecological enterprise-ecological park-ecological countryside-ecological city-ecological region＂circular economic industrial mode.Specifically，it may study and establish objectives，ideas and policies of circular economy development from enterprise，park，and city aspects，to drive market-oriented and industrialized development of circular economy.

（iii）Building excellent agricultural sci-tech model parks.The agricultural sci-tech model park is an incubator，distributing center and radiating source of new technology and achievement，and it is favorable for promoting extension and application of agricultural technologies.For example，it can launch pilot project in industrial leading enterprises and agricultural sci-tech model parks，and set up a batch of model enterprises and parks.This is an effective method to explore suitable mode for developing circular agriculture.In addition，it is required to increase sci-tech content of sci-tech model parks with conversion of high sci-tech achievement as guide，and introduction of advanced and suitable technologies as breakthrough point， constantly introduce， research，and extend new products，technologies and processes，bring into full play functions，and promote development of circular agriculture.

4.5 Increasing support and proving powerful guarantee

（i）Establishing and perfecting legal system in accordance with actual conditions.It is recommended to study and establish legal system for circular agriculture as soon as possible，implement clean production in accordance with laws，study and establish producer responsibility extension system，and put more effort in supervision in compliance with laws.

（ii）Establishing and perfecting various systems.In system economics，system is more important than technology，good system will promote innovation，while bad system will hinder innovation.To solve three key problems，namely，transformation and upgrade of agriculture，ecological protection or rural areas，and training and education of farmers，government should establish proper system.Also，it should increase performance of circular economic development in the performance assessment of leading cadres，to guide leading cadres to value circular agriculture and develop circular agriculture from thought and action.

（iii）Providing policy favor.In taxation，credit and service，it should provide favorable and preferential policies.It is recommended to guide relevant organizations and individuals to actively launch key projects and leading enterprise project for circular agriculture，and build circular industry for waste recycling.For some major projects，it may provide support such as direct investment，fund subsidy，or discount loan，and guide various financial institutions to provide credit support for projects favorable for promoting development of circular economy.

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