Bigfoot: The Nitrogen Problem

Less than 5% of the nitrogen added to crops to feed animals ends up as meat in our mouths. The rest is wasted and enters the environment with potentially devastating effects. Here...
14 August 2012


Bigfoot is the stuff of legends - a large, hairy, man-like creature that hides in the woods or high in a mountainous cave. Some believe he is a spiritual guide or an "elder brother" sent to watch over us and warn us of our miss-doings. There are active groups who post sightings of this mythical being on websites and assemble to search for clues of his existence. But what if they are looking in the wrong place? Looking for the wrong creature? Looking for the wrong footprint?

I would argue that real bigfoot is the collective impact of human actions that have led to the doubling of amount of nitrogen cycling on earth. Together we leave behind a trail of environmental destruction that could rival any large track you might imagine. In the past three essays we explored the importance of nitrogen, how humans have altered the amount of it cycling in the biosphere, and some of the negative environmental changes that occur when excess nitrogen enters coastal systems. Now, I want to tell you about the top two ways you can reduce your nitrogen footprint.


First: you can make an impact by simply eating less meat. Nitrogen (N) pollution is largely driven by our consumptive habits. In fact, there is a strong correlation between a country's wealth and their use of fertiliser, and between income and per-capita protein consumption (Nixon 1995). Protein consumption is important because it provides the nitrogen in our diets that we ultimately excrete into the environment. And while there are important cultural factors that dictate the types and amounts of meat consumed, the general global pattern is that meat consumption increases with wealth (Nixon and Fulweiler 2009).

Of course, the meat we consume, and the nitrogen we excrete in waste, is not the only concern. Another important problem is that our agricultural practices, in general, and the production of meat in particular, are remarkably inefficient. Of the 170 million metric tons of nitrogen (the equivalent of more than one and a half million blue whales) humans apply to cropland, only 12% actually ends up in our mouths (Galloway et al. 2003). In other words, it takes 100 kg (220 lbs) of nitrogen in corn to produce 5 kg (11 lbs) of edible nitrogen in beef -- but the remaining 95 kg of nitrogen is lost to the surrounding environment (Nixon and Fulweiler 2009).

A recent analysis reported that the excess nitrogen in the environment costs the European Union between 100 and 460 billion Euros per year (Sutton et al. 2011). You needn't go vegetarian, although that would help! Because by simply eating smaller portions of meat, or cutting back on the number of days each week you consume meat, you will decrease your nitrogen footprint.


Second: consume less energy. All of the nitrogen involved in energy production is lost to the environment. While you can't alter how electricity is generated, you can change how you use it. Turn off your lights, buy energy efficient appliances, unplug electronics when not in use. To lessen the nitrogen release during the burning of fossil fuels simply turn down your heat in the winter and lower your air conditioning in the summer. Take public transportation or, better still, walk or bike to work: exercise and an environmental benefit rolled into one.

Key to success is that we convince our friends, family, maybe even the person next to us on the train to make these changes too. Individual actions are important but it is the sum of these actions that will deliver the most significant impact. Become the real stuff of legends. Become an environmental steward of our fragile coastlines and feel empowered -- you can help create a sustainable future for all life on Earth...


Galloway, J. N. and others 2003. The nitrogen cascade. Bioscience 53: 341-356.

Nixon, S. W. 1995. Coastal Marine Eutrophication - a Definition, Social Causes, and Future Concerns. Ophelia 41: 199-219.

Nixon, S.W. & Fulweiler, R.W. (2009). Nutrient Pollution, Eutrophication, and the Degradation of Coastal Marine Ecosystems. In: C.M. Duarte, J. Culberston et al. (ed). Global Loss of Coastal Habitats: Rates, Causes, and Consequences. Bilbao: Fundacion BBVA. 184 p.

Sutton M.A., Oenema O., Erisman J.W., Leip A., van Grinsven H. and Winiwarter W. (2011). Too much of a good thing. Nature 472, 159-161.


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