CAREER: Sustainable Nitrogen Management across Spatial and System Scales

氮管理对可持续发展至关重要，但也具有挑战性。氮在提高农业生产力方面起着至关重要的作用，但它对环境有不利影响。提高作物和牲畜生产中氮素利用效率的技术和管理实践越来越容易获得，而且成本也越来越低，但在环境结果方面的改善有限。例如，在美国，作物生产中的氮利用效率（NUE）显著提高，氮肥的使用趋于平稳，但墨西哥湾的死区仍在扩大，主要是由农业生产中装载的氮和磷(P)驱动的。由于自然系统和人类系统的复杂反应以及利益相关者之间和跨空间尺度缺乏协调，作物或畜牧场氮素管理的改善并不一定转化为区域到全球范围内氮素污染的减少。该项目将开发一个氮素管理框架，该框架涵盖了跨系统和空间尺度的复杂氮素动态，但又足够简单，可以指导各利益相关者的政策和行动。本项目包括以下活动：(1)设计一个跨系统的分层框架，包括嵌套在动物-作物系统中的种植系统，嵌套在粮食系统中，最后嵌套在生态系统（CAFE）中；(2)基于CAFE系统框架，构建近30年来县域、流域、国家和全球不同空间尺度的氮预算数据库，识别各尺度氮管理的主要缺口；(4)促进学生和利益相关者共同开发模型、指标和沟通产品，以便有效地为氮管理决策提供信息。本项目将通过建立跨空间和系统尺度的综合氮管理理论框架，并将其应用于解开多个空间尺度上的氮挑战，从而推进对氮循环的认识。该方法利用生态和社会科学学科中氮循环研究的最新进展，将跟踪氮管理绩效随时间和空间的变化，确定经常被忽视的管理和工程差距，帮助实现创新的技术和政策解决方案，并协助和协调利益相关者的决策。将开设一门课程，为学生提供独特的机会，与利益攸关方共同开发旨在广泛分发和使用的通信产品。该项目开发的模型和指标将通过与切萨皮克湾项目、环境保护基金和几个国际组织的合作计划实施，寻求对政策的直接影响，并告知消费者和生产者。该项目产生的数据、指标、模型和课程材料将在网上公开，供其他科学家、教育工作者、农场顾问和学生使用。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。

Managing nitrogen (N) is fundamental, yet challenging, for sustainable development. Nitrogen plays a critical role in boosting agriculture productivity but it has adverse impacts on the environment. Technologies and management practices have become increasingly available and affordable to improve the efficiency of N use in crop and livestock production, but limited improvement has been observed in environmental outcomes. For example, Nitrogen Use Efficiency (NUE) in crop production has significantly increased and N fertilizer use has leveled off in the U.S., but the dead zones in the Gulf of Mexico are still expanding, mostly driven by N and phosphorus (P) loaded from agriculture production. The improvement of N management in a crop or a livestock farm does not necessarily translate to N pollution reduction on a regional to global scale due to the complex responses of natural and human systems and lack of coordination among stakeholders and across spatial scales. This project will develop an N management framework that encompasses the complex N dynamics across systems and spatial scales, yet is simple enough to guide policies and actions of various stakeholders.This project includes the following activities: (1) Design a hierarchical framework across systems including Cropping system nested within Animal- crop system, which is nested within the Food system, and finally nested within Ecosystem (CAFE); (2) Develop N budget databases according to the CAFE system framework on various spatial scales for the past three decades, including county-, watershed-, national, and global scales, and identify major gaps in N management at each scale; (3) Develop a case study for the Chesapeake Bay watershed to implement the CAFE system framework, and characterize spatial and temporal variations of N budgets and their drivers: (4) Facilitate the co-development of models, indicators, and communication products by students and stakeholders in order to effectively inform decision-making on N management. This project will advance the knowledge in N cycles by establishing a theoretical framework for integrated N management across spatial and system scales, and applying it to unpack N challenges on multiple spatial scales. This approach, leveraging the most recent advances in N cycle studies in both ecological and social science disciplines, will track changes in N management performance over time and space, identify management and engineering gaps that have been often neglected, help enable innovative technological and policy solutions, and assist and coordinate decision- making by stakeholders. A course will be developed to provide students unique opportunities to work with stakeholders on co-developing communication products targeted for wide distribution and use. Models and indicators developed from this project will are planned for implementation through collaborations with Chesapeake Bay Program, Environmental Defense Fund, and several international organizations, seeking direct impact on policies and informing consumers and producers. The data, indicators, models, and course materials produced by this project will be made publicly available online for use by other scientists, educators, farm advisors and students.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.