INFEWS: U.S.-China: Managing agricultural nitrogen to achieve sustainable Food-Energy-Water Nexus in China and the U.S.

中国和美国占全球作物和牲畜生产系统氮(N)投入的40%，作物氮利用效率（NUE）分别仅为26%和50%。尽管有许多技术发展，但近几十年来这些比率并没有显著提高。与此同时，两国只有大约三分之一的粪便被回收利用。这些从肥料和粪肥中流失到环境中的营养物质导致了严重的水污染、资源和能源的浪费，并可能使作物产量潜力无法实现。这些低效率突出表明，有必要确定社会经济和技术障碍，以提高作物和牲畜生产中氮的利用效率，以及粮食-能源-水（FEW）关系的可持续性。该项目的主要目标是调查和确定可行的方法，通过在中国和美国的作物和牲畜生产中进行氮素管理来提高氮素利用关系的可持续性。认识到美国和中国农业系统及其社会经济背景的差异，系统方法将有助于更好地理解改善氮素利用关系的各种社会经济和技术障碍，特别是农场经营之外的因素。并将有助于揭示每个国家面临的管理挑战。具体而言，该项目将：1)在中国和美国的县域尺度上，对作物和牲畜生产系统及其子系统的NUE和FEW可持续性进行表征；2)调查不同社会经济和生态驱动因素对氮肥利用、粪便循环利用和FEW可持续性的影响，比较两国的主要驱动因素，为氮肥利用的改善提供信息；3)开发一个政策分析工具，在每个国家的空间尺度上优化作物和畜牧业生产系统，以实现不同的少数可持续发展目标；4)评估1-3年在不同贸易关系情景下的挑战和机遇。该项目将通过评估作物和牲畜生产过程中氮素管理与氮素关系之间的复杂相互作用，推进对氮素关系动态的认识。该项目将采用最先进的模型和最近可获得的数据集和信息，并采用两国一致的方法。通过对氮在空间、时间和系统尺度上的流动的全面观察，该项目将有助于了解潜在的创新政策、技术发展、采用改进管理的障碍以及生产结构和贸易的潜在变化，以提高氮的可持续性。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

China and the U.S. account for 40% of the global nitrogen (N) inputs to crop and livestock production systems and have crop nitrogen use efficiencies (NUE) of only 26% and 50% respectively. Despite many technological developments, these rates have not significantly improved in recent decades. Meanwhile only about one-third of manure is recycled in both countries. These losses of nutrients from fertilizers and manures to the environment have led to serious water pollution, waste of resources and energy, and possibly unrealized crop yield potential. These inefficiencies highlight the need to identify the socioeconomic and technological barriers for improving the efficiency of N use in crop and livestock production, as well as the sustainability of the food-energy-water (FEW) nexus. The main goal of this project is to investigate and identify viable approaches to improve the sustainability of the FEW nexus through N management in crop and livestock production in China and U.S. Recognizing differences between U.S. and Chinese agricultural systems and their socioeconomic contexts, a systems approach will facilitate a better understanding of the varying socioeconomic and technological barriers for NUE improvement, especially the factors beyond farm operations, and will help to unpack the N management challenges of each country. Specifically, this project will: 1) Characterize NUE and FEW sustainability in China and the U.S. on a county scale for crop and livestock production systems and their subsystems; 2) Investigate diverse socioeconomic and ecological drivers for NUE, manure recycling, and FEW sustainability, comparing key drivers in the two countries to inform NUE improvement; 3) Develop a policy-analysis tool to optimize the crop and livestock production systems for different FEW sustainability goals on spatial scale within each country; and 4) Assess the challenges and opportunities for 1-3 under different trade relationship scenarios. This project will advance knowledge of the dynamics in the FEW nexus by assessing the complex interactions between N management and the FEW nexus throughout the processes of crop and livestock production. The project will employ state-of-art models and recently available datasets and information, using consistent methodologies in both countries. Taking a comprehensive view of N flows across spatial, temporal, and system scales, this project will inform understanding of potential innovative policies, technology developments, impediments to adoption of improved management, and potential changes in production structure and trade for improving FEW sustainability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.