Evaluation Of Two Circular Agriculture Modes In The South Of Loess Plateau

Circular agriculture is a new kind of agricultural mode with the feature of environmental friendly, economical and feasible. It is a good way to reduce the use of chemical fertilizer, reuse the waste and reduce the emissions of pollutant. However, the research on characteristics of circular agriculture modes in the south of Loess Plateau is limited. To some extent, it limits the development of circular agriculture in the study area. This study based on the theory and the practice of circular agriculture to analyse th energy flow efficiency, economic efficiency and the material input and output characteristics of different circular agriculture modes. This study selected two circular agriculture modes as the study objects including planting-breeding combined mode and integrated production mode in the Southern Loess Plateau to evaluate the energy flow, economic benefits and material circulation structure. The data of the study came from the investigation on the circular agriculture, field sampling, experimental analysis and professional literature. By using method of quantitative analysis, some results were obtain as following.(1) Organic energy is the main input of circular agriculture modes. For the circular agriculture modes, the degree of dependence on the market is small. The energy circulation index of planting-breeding combined mode and integrated production mode were 0.637 and 0.979 respectively, and it was 5.01 times and 3.15 times respectively as many traditional planting patterns. It showed that the circular agriculture modes had strong self-stability. The system dependency index of two kinds of circular agriculture modes were 6.80% and 37.39% respectively, higher than the traditional planting modes. There was stronger self-maintaining ability for agricultural cycle modes. The agriculture cycle modes included more subsystems and had more complex structures. More energy of per unit time and per unit area should be imported into the system, and it means that the flow density of agricultural cycle modes is far higher than that of the traditional mode. The operation of agricultural cycle modes should import more energy and they can also export more products. The four indicators of organic/inorganic energy, energy circulation index, system dependence and efficiency for solar energy utilization was much better than the traditional planting modes. But the energy flow density and energy input-output ratio index was lower comparing to the traditional planting modes. The energy yield of biogas subsystem was low, and the performance of the biogas subsystem need to be improved to enhance the energy efficiency of the whole mode.(2) The total cost, total revenue and cumulative net cash flow of the two circular agriculture modes was higher than the traditional planting modes. However, the economic ratio, cost profit margin and capital profit margin of the Pig-Methane-Apple Mode was lower than the traditional apple planting mode. That index of integrated agricultural mode was higher than the traditional walnut planting mode. It showed that the circular agriculture modes were financially feasible and need some improvement to increase the profit. The cumulative net cash flow of the Pig-Methane-Apple Mode had been positive value from the seventh year. The investment recovery period was 6.52 years later than the traditional apple planting pattern. It also showed that circular agriculture modes need longer time to recover the principal and the investment risk was higher. The cumulative net cash flow of the integrated agricultural mode in Yijun began to appear positive from the fourth year and its investment recovery period was 3.87 years, earlier than the single walnut planting mode. The investment risk for that circular agricultural mode was lower.(3) Some of the waste produced by the circular agriculture modes can be reused by the agroecological system. The organic carbon which was reused as feedback in the Pig-Methane-Apple Mode and the integrated production mode was 0.88 t and 11.67 t, respectively, higher than that of the traditional planting modes. By analyzing the proportion of the feedback output, we found that the circular agriculture modes has stronger self-sufficiency ability and they were more effective to reduce emissions of waste.The ratios between organic carbon of waste and organic carbon of output in the two circular agriculture modes were 0.209 and 0.258, respectively. They were lower than the traditional planting modes. The ratios between organic carbon of products and organic carbon of output and the ratios between output organic carbon and input organic carbon for the agricultural cycle modes were lower than those for traditional planting modes. Therefore the circular agriculture modes need to be improved to abtain higher efficiency of operations. For the characteristic of the indexes of the nitrogen cycle, the five positive indexes of nitrogen cycle(the feedback input / input, the feedback output / input, commodity output / output, commodity output / input and output/ input) were larger than the traditional planting modes. They showed that a greater proportion of nitrogen of the circular agriculture modes had gone back to the system and been reused. In the meantime, the circular agriculture modes had a higher proportion of nitrogen which was import to the market. The ratios between nitrogen of waste and nitrogen of output for the circular agriculture modes were smaller than those of the traditional ones. It meant that less nitrogen was wasted and exported in the circular agriculture modes.Circular agriculture modes could reduce the input of inorganic, save resources and reduce the emissions of pollutants. It was economically feasible. However, the structural configuration of the research object was unreasonable and further improvement was still needed.