CAREER: Sustainable Nitrogen Management across Spatial and System Scales

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.

Funding: National Science Foundation (5 years, NSF 2047165)

PI: X. Zhang; Senior Personnel: C. Davis