The sustainability of staple crops in China can be substantially improved through localized strategies

Abstract China's staple crop systems face great challenges to reduce the intensive use of agrochemicals and associated pollution while ensuring food security. Given the large variation in resource endowment, climatic and socioeconomic conditions, improving the sustainability of staple crops requires localized strategies. What strategies to pursue at local levels and to what extent they can improve crop sustainability remain unclear. Here, we present the first crop-specific county-level sustainability assessment of China's staple crops (wheat, maize, and rice) and their potentials for improvement using emergy analysis. Results show that the current mean emergy sustainability index of wheat, maize and rice is relatively low (i.e., at 2.35, 2.45, 1.94, respectively), indicating the production system of staple crops in China is relatively vigor but has still a large potential for improvement. Their sustainability is driven primarily by crop yield, nitrogen and phosphorus fertilizer use, and thus can be notably improved by such strategies as closing yield and nutrient-use efficiency gaps. Staple crops sustainability at the county level exhibits a large spatial heterogeneity, and the top 25% counties of emergy sustainability are mainly concentrated in the northern plain (for wheat), in the southwest regions and the central region (for maize), and in the southwest regions (for rice). More importantly, the county-level improvement potential shows a large spatial variation between strategies, suggesting that different regions would benefit more from different strategies. With the optimal strategy suited to each region, the mean emergy sustainability index of wheat, maize, and rice would increase by 35.6%, 40.5%, 26.6% compared with the current level, respectively. Overall, our study based on high-solution spatially-explicit analyses can inform farmers and policy makers on sustainable agricultural management, and provide a reference for other developing countries facing similar challenges. The comprehensive and detailed county-level crop database we have compiled can also be used broadly for analyses of China's agricultural pollution and food security.