Your Third Footprint

Chances are, having found this blog that posts about all things sustainability-related, you’ve heard of the concepts of your water footprint or your carbon footprint. HOWEVER, have you ever heard the term “nitrogen footprint” and do you know what it is? I figure I’d dedicate this post to the third lesser-known footprint. Without further ado, let’s learn about your nitrogen footprint!

Similar to the concept of your water footprint, the nitrogen footprint takes into account any nitrogen used in production and consumption of goods and services. Food production can have a huge influence on your nitrogen footprint, for instance. In food production, nitrogen in its usable form, or reactive nature, has many paths to be taken up by a plant, such as application of synthetic fertilizer or nitrogen fixation by legumes. However, plants only take up so much nitrogen and the rest remains in the soil, becomes runoff, or volatilizes into the atmosphere. As a result, the excess of reactive nitrogen has many ecosystem and human health implications, such as smog, acid rain, respiratory disease, and coastal dead zones.

The nitrogen cycle. Image from

See the diagram of the nitrogen cycle above? As a result of increased crop production, reactive nitrogen production increased through use of the Haber-Bosch process, which converts nitrogen gas (N2) to ammonia (reactive nitrogen). In addition to synthetic fertilizers, ammonia is used in the production of nylon, plastics, resins, animal and fish feed supplements, and explosives. Plus, nitrous oxide from power plants is 300 times more potent as a greenhouse gas than carbon dioxide (the poster child of greenhouse gases). Nitrous oxide depletes stratospheric ozone, which is the ozone that protects us from harmful UV-A and UV-B rays. Bottom line: Like your water and carbon footprints, living a green life should also emphasize decreasing your nitrogen footprint.

So what can you do? For starters, try this nifty nitrogen footprint calculator from the Chesapeake Bay Foundation or this one from What can lifestyle choices can you make differently? Recall that ammonia, the reactive form of nitrogen, is used to produce animal and fish feeds. One step you can take is to shift your diet by decreasing your meat intake. Rather than spray fertilizer all over your lawn (hey, the majority of fertilizer applied will probably become runoff and pollute waterways), try composting or reject lawns completely. Now that you’re more aware of the impacts of your choices and the alternatives you can make, go forth with a small nitrogen footprint!


Featured image from


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