Cow manure has long been used as a fertilizer for crops and gardens. Not as toxic as chemical fertilizers, manure adds beneficial organic material to soils, which helps prevent soil compaction. Soils are better able to retain moisture. However, despite these benefits, agricultural runoff remains a leading cause of water pollution, according to the U.S. Environmental Protection Agency (EPA).
Several factors determine the nutritional value of cow manure for soils and whether manure actually has environmental benefits, including the animal's diet, its bedding, and the animal's age.
Runoff from manure increases nitrogen and phosphorus levels in waterways, causing explosions of algae growth that can lead to fish and plant die off, even to the point of creating aquatic dead zones.
According to a study published in Nature GeoScience, cow manure is a leading contributor of atmospheric nitrous oxide, one of the major greenhouse gases.
The Cow Power program, part of Central Vermont Public Service (CVPS), has developed technology that takes cow manure and converts it to energy, which indicates that cow manure can have beneficial environmental effects.
A study published in the Institute of Physics' Environmental Research Letters estimates that cow manure can generate up to three percent of North America's energy needs, making it a possible part of the solution to global warming.
- Image by Flickr.com, courtesy of John Haslam