The Nitrogen Footprint Tool Network: A Multi-Institution Program to Research and Reduce Nitrogen Pollution
Humans release reactive nitrogen into the environment at a rate that is 4 to 5 times as large as from natural terrestrial processes. They do this by producing and applying nitrogen fertilizers, cultivating crops that fix nitrogen from the atmosphere and burning fossil energy. This leads to detrimental impacts on ecosystems, water quality and air quality, including excessive algal blooms that deplete oxygen in water bodies and harm aquatic life, smog, acid rain, forest dieback, stratospheric ozone depletion and an enhanced greenhouse effect. Colleges, universities and other institutions contribute to nitrogen pollution, both directly and indirectly. Activities of colleges and universities that contribute to nitrogen pollution include feeding students and employees, heating and powering facilities, commuting, traveling for work and study abroad, fertilizing college grounds, and conducting research.
Researchers at seven institutions collaborated to measure and compare their nitrogen pollution, or nitrogen footprints, and analyze options for reducing their footprints. The institutions participating in this research are Brown University, Colorado State University, Dickinson College, Eastern Mennonite University, Marine Biological Laboratory, University of New Hampshire, and University of Virginia. Each is a member of the Nitrogen Footprint Tool Network (NFTN), a network that is initiated by the University of Virginia and is coordinated by Elizabeth Castner. The research was conducted using the Nitrogen Footprint Tool (NFT), a calculator developed by Allison Leach while at the University of Virginia.
Results of the collaborative research were published as a collection of articles in Sustainability: The Journal of Record. One of the papers, “The Nitrogen Footprint Tool Network: A Multi-Institution Program to Research and Reduce Nitrogen Pollution,” provides an overview of the project and presents cross-institution comparisons of results.
Calculated footprints for the seven institutions range from 7.5 metric tons of nitrogen (MT N) at the Marine Biological Laboratory to 444 MT N at the University of Virginia. The nitrogen footprints correlate strongly with institutional population, but there is a wide range of per capita footprints, from 7 kg N per full-time equivalent person at Eastern Mennonite University to 27 kg N at Dickinson College. Factors that contribute to differences in per capita nitrogen footprints include the proportion of an institution’s population living on campus with full or partial meal plans, dietary choices, energy sources and engagement in research that is nitrogen intensive.
Upstream food production is the largest source of nitrogen pollution for five of the institutions, contributing 50% of the footprint on average, followed by utilities, which contribute 33% on average. The exceptions are the University of Virginia, where utilities account for 52% of its nitrogen footprint due to heavy reliance on coal-fired power, and Colorado State University, which has extensive agricultural research activities that account for 49% of its nitrogen footprint.
The effects of selected nitrogen mitigation measures were modeled and simulated for each institution using the NFT. Many of the measures align with existing sustainability initiatives such as climate action plans, the Real Food Challenge, the Food Recovery Network and Meatless Mondays. Measures studied include reducing food purchases through more efficient management practices; substituting protein sources associated with low levels of nitrogen pollution for protein sources associated with high levels (e.g. substituting chicken for beef, or substituting legumes and grains for meat); energy conservation; and transition to clean, renewable energy sources.
The results indicate that significant reductions in institutional nitrogen footprints are feasible by optimizing food purchasing, reducing the consumption of animal products, minimizing food waste and reducing dependence on fossil fuels for energy. Each of the participating institutions have either adopted nitrogen pollution reduction goals or are considering their adoption as a result of participating in this research.
The nitrogen footprint research has engaged undergraduate and graduate students, faculty members and staff. In addition to the seven institutions that participated in the published comparison study, thirteen new members of the Network are currently calculating their footprints using the NFT.
The purposes of the NFTN are to engage higher education institutions in research to understand and measure their nitrogen footprints, analyze nitrogen mitigation options, and act to reduce nitrogen pollution as an integral part of their sustainability programs. Members of the Network meet for annual workshops, share information, compare findings, collaborate on research, work to improve the Nitrogen Footprint Tool and advocate for nitrogen pollution reduction at their institutions and other higher education institutions. The NFT is available for institutions and individuals to use to understand their contribution to nitrogen pollution release and includes testable scenarios for reducing their nitrogen footprint. Members of the network are also working on a new tool that will allow them to integrate tracking and management of their nitrogen and carbon footprints.
The research is relevant to all higher education institutions. This is demonstrated by the diversity of institutions that participated in this work, which includes large public universities with substantial research activities and ancillary services such as a hospital, mid-size private universities, small residential liberal arts colleges and a research lab.
The research can have a large impact on the sustainability performance of higher education institutions. The accumulation of reactive nitrogen in the environment is one of the most important environmental problems of our times. Much like carbon pollution and climate change, higher education institutions are significant contributors to nitrogen pollution. They can also be leaders in reducing nitrogen pollution. Our research provides a framework for all higher education institutions to engage in this important work.
Authors: Elizabeth A. Castner, Allison M. Leach, Neil Leary, Jill Baron, Jana E. Compton, James N. Galloway, Meredith G. Hastings, Jacob Kimiecik, Jonathan Lantz-Trissel, Elizabeth de la Reguera and Rebecca Ryals.