Development practice and promotion route of circular agriculture in China

The long history of circular agriculture is characterized by theoretical and practical exploration tracing back to ancient agricultural civilizations in China. Circular agriculture has already been engaged to combine millet cultivation and pig farming at the Dadiwan site in Qin'an, China, during the Neolithic period more than 5,500 years ago. Various modes of ecological cycle have been applied over the course of several thousand years in conventional Chinese agriculture, such as rice-fish farming, mulberry-based fish ponds, crop rotation complementarity, and courtyard economy. Since the reform and opening-up, remarkable achievements have been realized to clarify the ecological balance and resource recycling. But the agriculture still relies heavily on the extensive use of agricultural inputs, like fertilizers, pesticides, and agricultural films, leading to the increasingly prominent issues of environmental pollution and ecological damage. The agricultural growth mode is required to reduce the input, consumption, and pollution. Therefore, it is very necessary to enhance the utilization and recycling levels of agricultural resources in circular and sustainable agriculture. Circular agriculture is significantly practical and has far-reaching strategic importance. New productive forces can also be developed in green and high-quality agriculture. This article aims to clarify the essential connotation of circular agriculture. The concept of green development was dominated by constructing circular agriculture. A multi-level material and energy recycling system was then realized via technological innovation and management. A closed-loop production model was obtained with low material input, high efficiency of resource utilization, and low environmental pollution. Four key characteristics of circular agriculture were proposed: source reduction, process recycling, high-value output, and low-carbon process. Four achievements were also highlighted, including the reduction of input quantity with high efficiency, the high level of waste resource utilization, the pollution and carbon reduction, as well as industrial value-added and efficiency enhancement. The development mode of circular agriculture was summarized from three perspectives: Firstly, the implementation subject was divided into small-scale circulation among individuals, medium-scale circulation among industries, and large-scale social circulation; Secondly, industrial composition was divided into the internal circulation within the planting industry, circulation between planting and breeding, circulation among planting, breeding, and processing, as well as the production-lifestyle circulation; Thirdly, core linkage was divided into the circular agriculture mode that linked by fertilization, energization, feed production, substrate production, and raw material production. A summary was also given on circular agriculture: Firstly, the top-level design was still limited to coordinating some measures in different planting and breeding segments. It was difficult for the key "links" to form a "chain" and then create a joint force; Secondly, technological equipment was required to upgrade technological equipment, such as high energy consumption, low stability, and efficiency; Thirdly, some regulations were still required for the circular agriculture. Previously, much effort was focused mostly on pollution prevention and control. It was still lacking specific regulations tailored to circular agriculture; Fourthly, it was still lacking decision-making on the subsidy policies at the national level. The advanced experiences of developed countries were also summarized in circular agriculture, including comprehensive legal systems, integrated models tailored to local conditions, mature and sound management, advanced and practical technological equipment, as well as publicity and education. Finally, the practices of circular agriculture were drawn from the developed countries, according to the national conditions. Key points and paths were proposed to develop circular agriculture: Firstly, the internal circulation system of the planting industry was optimized, and suitable models upgraded, according to the local conditions. The waste collection, storage, and transportation were optimized to focus on the critical step of straw decomposition, and high-value-added functional products; Secondly, the planting and breeding circulation were also reconstructed to explore and implement the nutrient management. Technological equipment was developed for nutrient loss control. A long-term mechanism was obtained for planting and breeding circulation; Thirdly, the production, processing, and sales circulation were extended to strengthen the raw material loss reduction, processing loss reduction, and comprehensive utilization of processing by-products; Fourthly, the production and lifestyle circulation were improved for the classification and collection of perishable wastes in the collaborative treatment of production and lifestyle waste. Meanwhile, specific paths were obtained to promote structural adjustment, and scientific and technological support. A number of demonstration projects were conducted to develop circular agriculture and agricultural power.