Citation:

Compton, J. Cost of nitrogen use in the US. True Cost of American Food, San Francisco, CA, April 14 - 17, 2016.

Impact/Purpose:

Growing human demands for food, fuel and fiber have accelerated the human-driven fixation of reactive nitrogen (N), one of the most dramatic changes to the sustainability of Earth’s systems. Recent work at EPA has quantified the inputs of nitrogen to the conterminous US, and determined that approximately 65% of the N fixed within the US is used in agriculture as synthetic N fertilizers and by N-fixing crops such as alfalfa and soybeans. Leakage of from human activities to the environment can result in a host of human health and environmental problems including effects on human respiratory health via mortality, hospital visits and loss of work days due to the formation of smog, costs associated with treatment and replacement of drinking water contaminated with nitrate, losses to recreation and fisheries resulting from algal blooms and hypoxia in freshwater and coastal ecosystems. This work was presented at the recent True Cost of American Food meeting hosted by the Sustainable Food Trust. The environmental costs are just one area that is important to the attendees of this meeting, but also include implications for human health, social justice, animal welfare, farm systems, economics, methods for incorporating ecosystem services, communications and policy and voluntary incentive options for change. This abstract is part of SHC 4.61.

Description:

Growing human demands for food, fuel and fiber have accelerated the human-driven fixation of reactive nitrogen (N) by at least 10-fold over the last century. This acceleration is one of the most dramatic changes to the sustainability of Earth’s systems. Approximately 65% of the N fixed within the US is used in agriculture as synthetic N fertilizers and by N-fixing crops such as alfalfa and soybeans. Leakage of from human activities to the environment can result in a host of human health and environmental problems (see figure). These costs include effects on human respiratory health via mortality, hospital visits and loss of work days due to the formation of smog, costs associated with treatment and replacement of drinking water contaminated with nitrate, losses to recreation and fisheries resulting from algal blooms and hypoxia in freshwater and coastal ecosystems. Often these harmful effects are not reflected in the costs of the food, fuel, and fiber that depend upon N use. A recent US EPA study (Sobota et al. 2015) quantified the potential damage costs associated with N leaked from the following sources: synthetic and manure fertilizers, crop N-fixation, wastewater, and fossil fuel combustion. Each source was traced through the nitrogen cascade to the environment (see figure) in order to connect to existing data on the costs of specific forms of N in specific situations in order to calculate the annual damage cost of anthropogenic N. Estimates of N leakage ranged from <1- 125 kg N ha-1 yr-1, with approximately 71% of this N leaking into freshwater ecosystems. Areas with substantial agricultural N inputs tended to have greater damage costs when compared to urban and non-cultivated lands. Eutrophication of freshwater ecosystems and respiratory effects of atmospheric N pollution were important across all the sites. For the US, potential health and environmental damages of anthropogenic N in the early 2000s totaled $210 billion per year USD (range: $81 - $441 billion per year). Nearly 75% of the damage costs were associated with agricultural N leakage and effects on aquatic systems. The costs associated with agricultural N used were approximately $157 billion, ranking it as the source with the greatest damage costs. Similar work in the EU also identified $45-296 billion in damages associated with agriculture. Significant data gaps remain in our ability to fully assess N damages, such as damage costs from harmful algal blooms and drinking water contamination. Despite the gaps and uncertainties in these estimates, this work indicates that the costs of N use are substantial and can be used as a starting point to engage stakeholders and inform management of N pollution. Reference: Sobota, D.J., J.E. Compton, M.L. McCrackin and S. Singh. 2015. Cost of reactive nitrogen release from human activities to the environment in the United States. Environmental Research Letters 10:025006.

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