The Effect of Agriculture on Ground-Level Ozone
Agriculture is a necessary evil. Although it is essential for food production and other industry, agricultural practices exert a heavy toll on the environment. Farm runoff remains a major source of water pollution. Fossil fuel emissions from farm machinery release carbon dioxide into the atmosphere. Other agricultural operations also contribute to air pollution and the formation of ground-level ozone.
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Effects
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In order to understand the role of agriculture on ground-level ozone, it is necessary first to define this environmental condition. Ground-level ozone is the product of the so-called greenhouse effect. Concentrations of greenhouse gases, including carbon dioxide, nitrous oxide, and other gases, create a type of solar blanket that traps the ground-level heat from leaving the land surface at night. The effect is an increase in the surface temperature of the Earth. This atmospheric layer differs from the protective ozone layer found farther up in the atmosphere.
Significance
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Agriculture plays a significant role in the development of the ground-level ozone layer. According to the 2010 U.S. Greenhouse Gas Inventory Report, agriculture contributes about 6 percent of the total man-made greenhouse emissions. Although that may sound insignificant, agriculture is also responsible for 25 percent of total methane production. "Science Daily" estimates that methane, although not as abundant, is potentially 20 times more potent.
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Types
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There are several agricultural sources of greenhouse gas emissions. Enteric fermentation occurs in the digestive systems of ruminants such as cows. This process releases methane into the atmosphere, a major contributor to agriculture's role in the formation of ground-level ozone. Much attention regarding the greenhouse effect has focused on livestock. However, according to the U.S. Environmental Protection Agency (EPA), fertilizer application on crops accounts for 68 percent of the total U.S. nitrous oxide emissions.
Trends
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Overall, the number of American farms has declined from 1900 to 1997, according to U.S. Department of Agriculture figures. That fact might lead you to believe the effect of agriculture on ground-level ozone is diminishing. However, while the number has gone down, the size of the average farm has increased from just over 100 acres to just shy of 500 acres, nearly a 500 percent increase. According to the EPA, overall methane emissions increased more than 14 percent from 1990 to 2008.
Prevention/Solution
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The complexity of reducing agriculture's contribution to ground-level ozone is illustrated by the many mitigating factors, which add to its effects. Scientists have recognized how essential agriculture is. So rather than trying to reduce production, they have found ways to embrace its existence. The Cow Power program, part of Central Vermont Public Service (CVPS), is an example of such a program. Cow Power uses the heat energy of methane to provide a source of clean, renewable energy. Similar programs on other agricultural lands can help rid the atmosphere of excessive methane while reducing the draw on fossil fuel burning energy plants.
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References
- U.S. Environmental Protection Agency: Protecting Water Quality from Agricultural Runoff
- U.S. Environmental Protection Agency: Greenhouse Gas Emissions
- U.S. Environmental Protection Agency: 2010 U.S. Greenhouse Gas Inventory Report
- U.S. Department of Agriculture: Trends in U.S. Agriculture
- Science Daily: Methane's Impacts On Climate Change May Be Twice Previous Estimates
Resources
- Photo Credit cow image by david purday from Fotolia.com
