Most people have heard of a carbon footprint, but what about a nitrogen footprint? Here’s what you need to know about this crucial element, its connection to the environment, and why it is a pillar of UVA’s sustainability goals.
What is a Nitrogen Footprint?
Nitrogen is essential for life on Earth, as it helps plants grow, feeding our rapidly growing human population. A nitrogen (N) footprint is defined as the total reactive nitrogen released into the environment as a result of human activities.1 For simplicity, we’ll refer to this as nitrogen. The challenge is that too much nitrogen can cause a cascade of negative environmental impacts, including smog and haze, waterway pollution, and contributions to climate change. So here is where the nitrogen dilemma comes in:
We simply can’t live without nitrogen, yet too much of it is damaging the environment and harming human health.
Nitrogen enters the environment as a result of food production, energy use, transportation, wastewater, and more. The energy component is due to fossil fuel combustion, which contributes to both nitrogen and greenhouse gas footprints in various ways. However, the largest singular component that truly distinguishes nitrogen pollution is food production, a sector that often consists of over half of an institution like the University of Virginia’s N footprint.
Figure 1. UVA’s nitrogen footprint by sector. The horizontal green line indicates the UVA Board of Visitor’s goal to reduce the University’s nitrogen footprint by 30% by 2030. Note that the N footprint is expected to increase based on UVA growth projections, so work still needs to be done for the University to meet this goal, despite meeting it in 2023 and the past few years.
In Figure 1, you can see UVA’s nitrogen footprint over the years, which is found in the UVA Sustainability Annual Report.2 The light green segments dominating the University’s N footprint represent the food portion of the footprint.
UVA’s Nitrogen Footprint
The large food footprint shown here is primarily caused by animal-based products, especially beef, which require more resources to reach your plate. An individual eating a beef burger would have a higher nitrogen footprint for that meal than someone eating a turkey burger and even higher than someone eating a bean burger (Figure 2). If you eat an average omnivorous diet, switching out just two servings of beef per week with a vegetarian option would lower your N footprint by 15%! For a large university like UVA with many students eating at UVA Dine locations, the cumulation of food it serves on Grounds becomes a determining factor in the magnitude of its N footprint.
Figure 2. A beef burger has the largest nitrogen footprint, while a plant-based burger has the smallest. The bars indicate the nitrogen footprint of a 5-oz (142-gram) patty of each protein source. Note that the bars do not indicate the amount of N within the patty itself.
What’s up with beef?
Not all protein sources come with the same environmental cost. If you are wondering why beef has a higher nitrogen footprint, the answer lies in the process of raising livestock. A study by the NIH found that up to half of the nitrogen losses to the environment occur during the feed production stage of the beef supply chain.3 Animal feed production relies on the use of synthetic fertilizers to grow crops such as corn. When we eat corn on the cob, the growing process stops here; if we instead use the corn as feed to raise livestock, this adds more to the story. Cattle also inefficiently use the nitrogen they consume, so they need a lot of feed to produce necessary proteins in their bodies. This explains why a beef burger results in a much higher nitrogen footprint than other protein alternatives.
Why it matters
Nitrogen pollution is very localized. Throughout the Chesapeake Bay Watershed, thousands of agricultural fields rely on synthetic fertilizer to grow their crops. Runoff from these fields carries excess nitrogen from fertilizer into the bay, fueling eutrophication, algal blooms and “dead zones” – areas where fish, crabs, oysters, and other aquatic life suffocate from a lack of oxygen in the water.4
UVA is located in Charlottesville, Virginia, within the Chesapeake Bay watershed. Food purchased by UVA or by its students that are produced within this watershed directly affects Charlottesville and other communities nearby, posing a direct threat to wildlife, ecotourism, the fishing industry, environmental justice, and much more. In this way, reducing UVA’s nitrogen footprint will have returning benefits for the University and the community it resides in.
The good news is that excess nitrogen in the environment can be reduced – and UVA is already making strides to do so! UVA Dine has cut back on the amount of beef purchased for its dining halls, while shifting towards chicken. Plus, recent renovations of dining facilities and meal options now encourage tasty plant-forward dishes. Nitrogen pollution into the environment remains a critical concern, however, and more work needs to be done for UVA to meet its 2030 goals.
What now?
Your meal choices can make an incredible difference. Small, consistent changes like swapping beef for poultry – or even better, replacing it with plant-based proteins – even once a week can significantly lower your personal nitrogen footprint. Try tracking your own N footprint using the N-Print calculator!
For inspiration, check out some ideas below on how to reduce your personal environmental footprint, as written by UVA students and community members at the Nitrogen Working Group tabling on Grounds!
Finally, living more sustainably isn’t all-or-nothing. You don’t have to be perfect to make a difference. Realistic changes to your routine can have a meaningful cumulative impact that are more considerable than you may think. Keep this in mind the next time you grab a meal, whether on Grounds, at a restaurant, or at home. It all counts!
Learn more about the Nitrogen Working Group
The University of Virginia was the first to calculate a nitrogen footprint at an institutional level. nitrogen footprint. In 2010, Environmental Sciences undergraduate student Allison Leach developed and published her work on UVA’s nitrogen footprint (Leach et al., 2012). In 2014, because of many years of leadership by Professor Jim Galloway, the Nitrogen Working Group was formed as a subgroup of the Committee on Sustainability and then later, UVA’s Office for Sustainability, to measure the University’s nitrogen footprint and to find ways to reduce it. Since its foundation, over 50 students have been NWG student employees. The group’s interventions around Grounds include working with UVA Dine to increase their sustainable food ratios, conducting hands-on research at Morven Sustainability Lab, and generating student engagement through outreach. These are all crucial strategies to lower the University’s nitrogen footprint and to reduce environmental damage to the greater Charlottesville area.
To learn more, you can find the NWG’s website here!
Phoebe Hall is a student intern for the UVA Nitrogen Working Group’s Social Outreach Team, along with Molly Kaufman and Angelia-Anne Irvine. Under the leadership of Libby Dukes and Professor James N. Galloway, the team works to encourage sustainable behaviors within the university community and beyond to lessen our impact on the environment, particularly with respect to nitrogen.