CAREER: Sustainable Nitrogen Management across Spatial and System Scales

对于可持续发展来说，管理氮(N)是基本的，但也是具有挑战性的。氮在提高农业生产力方面发挥着关键作用，但它对环境也有不利影响。在作物和畜牧业生产中提高氮素利用效率的技术和管理做法已变得越来越可用和负担得起，但在环境成果方面的改善有限。例如，美国作物生产中的氮素利用效率(NUE)显著提高，氮肥使用量持平，但墨西哥湾的死亡区仍在扩大，主要是由农业生产带来的氮和磷(P)推动的。由于自然和人类系统的复杂反应以及利益攸关方之间和跨空间尺度的缺乏协调，作物或畜牧场氮素管理的改善并不一定转化为在区域和全球范围内减少氮素污染。该项目将开发一个氮管理框架，该框架涵盖了系统和空间尺度上的复杂N动态，但足够简单地指导不同利益相关者的政策和行动。该项目包括以下活动：(1)设计一个跨系统的分层框架，包括嵌套在动物-作物系统内的种植系统，嵌套在食物系统内，最后嵌套在生态系统(CAFE)内；(2)根据CAFE系统框架，在过去30年的不同空间尺度上，包括县、流域、国家和全球尺度，开发N预算数据库，并找出每个尺度上N管理的主要差距；(3)开发切萨皮克湾流域实施CAFE系统框架的案例研究，并描述N预算的时空变化及其驱动因素：(4)促进学生和利益相关者共同开发模型、指标和交流产品，以便有效地为N管理决策提供信息。该项目将通过建立跨空间和系统尺度的N综合管理的理论框架，并将其应用于在多个空间尺度上拆解N个挑战，从而在N个周期内推进知识。这一方法利用生态和社会科学学科中N周期研究的最新进展，将跟踪N管理绩效随时间和空间的变化，找出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，并协助和协调利益攸关方的决策。将开发一门课程，为学生提供独特的机会，与利益相关者合作，共同开发面向广泛分发和使用的通信产品。根据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来计划实施，寻求对政策的直接影响，并向消费者和生产商提供信息。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NSF的法定使命，并通过使用基金会的智力优势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.