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The Effects of Organic Farming Practices on Nitrogen Pollution

Jul 04, 2013
Photo Credit: Bob Nichols

Photo Credit: Bob Nichols

The Organic Center is working with Professor James Galloway, Ariel Majidi, and Allison Leach at the University of Virginia to investigate the effect of different farming systems on nitrogen pollution.  

Over the last century food production has played a large role in the increased production of excess reactive nitrogen (all nitrogen forms other than N2).  This overabundance of nitrogen accumulates in the environment, leading to nitrogen pollution.  Nitrogen pollution is a problem, because it can cause eutrophication of aquatic environments and  “Dead Zones” in the coastal ocean.  It also contributes to climate change, acid rain, smog, biodiversity loss, and more.  


In reaction to the many environmental and human health consequences associated with conventional farming, some growers have turned to organic methods, with the hopes that avoiding synthetic pesticide and fertilizer application will decrease the negative impacts of food production.  Organic farming may have a beneficial effect on nitrogen pollution, because organic farms recycle their plant material through composting, and are prohibited from using synthetically produced nitrogen fertilizer.  They also commonly use crop rotations, which can prevent high nitrogen runoff rates as a result of soil stripping and erosion.  However, manure and nitrogen-fixing cover crops are also used on organic farms, which increase the amount of nitrogen in the soil, so the impact these farms play on nitrogen pollution reduction is still unknown.  


Farm runoff.   Photo Credit: Lynn Betts

Farm runoff
Photo Credit: Lynn Betts


To quantify the level of contribution to nitrogen pollution from conventional versus organic farms, this project examines the virtual nitrogen factors of 4 different crop types for each farming method.  Virtual nitrogen factors describe the amount of nitrogen released into the environment per unit of nitrogen endogenous to that food, and have been used successfully to quantify the nitrogen footprint of personal diets and institutions. These factors essentially describe how much nitrogen is lost to the environment during the food production process for different common food types.  


Professor Galloway and Allison Leach have spearheaded several other studies examining nitrogen footprint models, including the development of The Nitrogen Calculator.  The N-Calculator is a tool that enables individuals to calculate their personal impact on nitrogen pollution by looking at food group consumption, housing, transportation, and goods and services choices.  Other tools that are in development can be used by institutions, organizations and communities.  In the future we hope to add different farming practices (including organic) to the N-Calculator so that people can easily see how much of a difference eating organic makes on nitrogen pollution!

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