Analysis of economic efficiency and energy flow characteristics of a circular and integrated agriculture model in the Loess hilly region

Abstract: As the foundation of the national economy industry, agriculture is facing the increasingly prominent resource constraints and environmental problems. At present, the development of agriculture in China has been mainly based on an extensive predatory mode of operation with one-way flow of resources, agricultural products, and wastes. Conventional production systems are characterized by high resource consumption, low material and energy utilization rates, and considerable pollutant emissions. Due to excess input of pesticides, fertilizers, and energy and food safety issues, the conventional production model has resulted in the exhaustion of agricultural resources such as water, land, and energy, destroying the eco-environment. While circular agriculture is a kind of new mode of agricultural development with the features of environmental friendly, economical and feasible. The use of ecological recycling in agriculture has been widely spread in China. Taking a circular integrated agriculture model in the Loess Plateau consisting of multiple subsystems (walnut and grain, pigs and poultry, and biogas) as a case, the energy flow feature and economic benefit were compared with the traditional agriculture model, to direct the development of agriculture in the Loess Plateau. The data of the study came from the investigation on the circular agriculture, field sampling and experimental analysis. By using method of flow analysis and cash flow analysis, some results were obtained as following. The indices of energy flow and economic benefit of the integrated agriculture model were superior to the traditional agriculture model. The operation of the integrated agriculture model imported more energy, which mainly was organic energy. The indicator of organic/inorganic energy of the integrated agriculture model was 46.2, which was 92 times of the traditional agriculture model. And its energy flow density was 2.7 times of the traditional agriculture model (7.0 MJ/（m2·a）), which was 19.7 MJ/（m2·a）.The indicators of energy circulation index, system dependence and efficiency of solar energy utilization were 0.98, 37.4% and 0.5%. While, due to the complex structure of the integrated agriculture model, the energy input-output ratio was lower comparedto the traditional agriculture model. The energy yield of biogas subsystem was low, and the biogas subsystem need to be improved to enhance the energy production of the whole mode. The result of economic benefit showed that the total cost, total revenue and total net present value were higher than those in the traditional agriculture model. And the cost profit margin, the annual average yield and economic ratio of the integrated agriculture model reached 137.6%, 4.6%, and 2.4. The cumulative net cash flow of the integrated production mode in Yijun began to showpositive effect from the fifth year and its investment recovery period was 4 years, and it showed that the traditional agriculture mode need longer time to recover the principal, so the investment risk is higher for the traditional agriculture mode. To sum up, the integrated agriculture model can effectively use the waste produced in the system, improve the efficiency of energy utilization, show better capability of producing benefit and enduring economic risks, for which it must have a good popularization value in the hilly region.