Nitrogen (N) is an essential element of many biomolecules and is crucial for life on earth. Nitrogen is a key driver of plant productivity for food, feed, fiber and fuel, and insufficient N in soils often limits agricultural productivity. Industrial/synthetic N-fertilizers have removed the N-limitation in many agricultural systems, although over-use of N-fertilizers threatens the environment and, ultimately, the sustainability of such systems. On the other hand, millions of resource poor farmers, especially in developing countries, cannot afford the expensive N-fertilizers to boost production and as a result suffer from very low crop yields. There is growing international awareness of these two main problems associated with N in agriculture as well as the need to coordinate funding and research to solve the problems at an international level. This project will establish the Plant Nitrogen Network (PlaNNet), an NSF Research Coordination Network (RCN) of researchers and other stake-holders within the U.S.A. and around the world that will play a leading role in designing and implementing research and development (R&D) strategies to address the problems of N in agriculture in different parts of the world. <br/><br/>Global challenges require global responses. Feeding 9 billion people in 2050 and maintaining stable food supplies into the distant future will require more-sustainable solutions to agriculture's N problems. Lack of coordination in R&D related to plant-N results in a global effort that is not as focused, efficient, and effective as it could be. This RCN aims to coordinate research activities related to the supply and utilization of N by plants with the long-term objective of enhancing the efficiency and sustainability of N-use in agriculture. Research challenges and opportunities include improving nitrogen use efficiency (NUE) in crop and pasture plants and exploiting biological nitrogen fixation in both natural and synthetic systems. Optimization of N-use in agriculture will also require improved agriculture management practices. PlaNNet will help to connect basic and applied researchers to facilitate a concerted effort to solve agriculture's N-problems. Research coordination network (RCN) activities will include: (i) development of a networking website that includes information about hundreds of researchers within the U.S.A. and around the world who are involved in plant N-related research, opportunities for collaboration, and educational resources; (ii) annual Workshops-Without-Walls, virtual meetings that will involve hundreds of participants in presentations, discussions, and consensus-building related to plant-N research and development; and (iii) satellite workshops at major conferences focused on specific aspects of plant N and agriculture. The activities of the RCN will be coordinated by a PlaNNet Steering Committee (SC) that will be composed of a broad cross section of the nitrogen research community balanced among different demographic groups.