黄土丘陵区山地立体种养循环生产能流特征与经济效益分析

为揭示陕北黄土丘陵区典型循环农业生产模式的功能和效益,研究以宜君县山地立体种养结合循环生产模式为例,分析了该循环生产模式的能量流动和经济效益特征。结果表明:山地立体种养结合模式的有机能/无机能比达到46.2,是传统种植模式的92倍;种养结合模式和传统模式的能流密度分别为19.7,7.0 MJ/(m2·a)。种养结合模式的系统内依存度为37.4%,远高于传统模式,显示出较强的系统自我维持能力和稳定性。种养结合模式的能量产投比为1.07,略小于传统模式的1.14,但其成本利润率、年均收益率和经济产投比分别达到137.6%、4.6%和2.4,均高于传统模式的81%、2.7%和1.8;种养结合模式和传统模式的投资回收期分别为4年和7年。综上,山地立体种养结合模式能够有效地利用系统废弃物,提高能量利用效率,表现出良好的经济效益和较强的抵抗经济风险的能力,在该丘陵区具有良好的推广价值。

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

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.