COS 19-4
How does consuming organic products affect my nitrogen footprint?

Monday, August 10, 2015: 2:30 PM
348, Baltimore Convention Center
Laura Cattell Noll, University of Virginia
James N. Galloway, University of Virginia
Allison M. Leach, Natural Resource and Earth Systems Science and The Sustainability Institute, University of New Hampshire, Durham, NH
Verena Seufert, Department of Geography, McGill University, Montreal, QC, Canada
Jessica Shade, The Organic Center, Washington, DC

Reactive nitrogen is necessary for crop and animal production, but when it is lost to the environment, it creates a cascade of detrimental environmental impacts including smog, acid rain, eutrophication, climate change and stratospheric ozone depletion. The nitrogen dilemma is to maximize the food production benefits of reactive nitrogen, while minimizing losses to the environment. 

Organic practices in food production attempt to reduce the detrimental impacts of agricultural systems on the environment and human health. This study explores the effects such practices have on nitrogen (N) pollution, in comparison to conventional food production practices.

To examine the effects of farming system on nitrogen lost during food production we used virtual nitrogen factors (VNFs) that quantify the amount of nitrogen lost to the environment per unit nitrogen consumed.


Our preliminary results suggest that there is no statistical difference between organic crop VNFs and conventional crop VNFs, which means that on average organic crop production and conventional production are comparable in terms of nitrogen losses during production. This is because while organic production results in more nitrogen availability for recycling, on average organic production methods also result in lower yields.

However, because conventional production relies heavily on the creation of new reactive nitrogen (Haber-Bosch, biological nitrogen fixation) and organic production primarily recycles existing reactive nitrogen (manure, crop residue) and only creates some new reactive nitrogen (BNF), our data suggest that organic production contributes less new reactive nitrogen to the environment than conventional production. Therefore, on a local scale, nitrogen pollution from organic crop production is comparable to conventional, but organic crop production introduces less new reactive nitrogen to the global pool.  Since there are larger differences between organic and conventional livestock production, the animal protein VNFs reflect a more complicated picture for which the VNF calculation must be adjusted.

In order to minimize the negative impacts of reactive nitrogen, consumers must make lifestyle choices that minimize their nitrogen footprint. With a deeper knowledge of the N losses from organic production relative to conventional, consumers will be more equipped to determine the potential sustainability of purchasing organic products.