Sustainability evaluation of soybean-corn rotation systems in the Loess Plateau region of Shaanxi, China

To reach the “Zero Hunger” sustainable development goal, increases in the efficiency, quality and sustainability of agricultural practices are needed. The Loess Plateau region is one of the most fragile regions in China, and crop rotation and crop straw recycling are receiving increasing attention in this region. To compare sustainability among different agricultural practices from both ecological and economic perspectives, we employed emergy analysis to comprehensively quantitatively evaluate corn-soybean rotation systems with and without the return of straw to the field in the central region of the Loess Plateau. The results showed that because of the poor natural conditions, both production practices depend heavily on significant inputs of resources and human activities from outside systems. The emergy sustainability index of the corn-soybean rotation with straw recycling system (0.131) was higher than that of the corn-soybean rotation without straw recycling system (0.079); however, neither system is sustainable, as they both produce high environmental loads and result in low production yields. These problems originate from the fragility of the ecosystem and long-term human exploitation of the ecosystem. Furthermore, neither system is ecologically or economically sustainable, and farmers suffer ecological and economic losses when selling soybeans on the market. This inefficiency is due to poor agricultural production methods and environmental conditions. Several insights into and suggestions for reducing environmental loads and improving productivity are presented in this paper.