Manure becomes pollutant as its volume grows unmanageable
By David A. Fahrenthold
Washington Post Staff Writer
Monday, March 1, 2010 Nearly 40 years after the first Earth Day, this is irony: The United States has reduced the manmade pollutants that left its waterways dead, discolored and occasionally flammable. But now, it has managed to smother the same waters with the most natural stuff in the world. Animal manure, a byproduct as old as agriculture, has become an unlikely modern pollution problem, scientists and environmentalists say. The country simply has more dung than it can handle: Crowded together at a new breed of megafarms, livestock produce three times as much waste as people, more than can be recycled as fertilizer for nearby fields. That excess manure gives off air pollutants, and it is the country’s fastest-growing large source of methane, a greenhouse gas. And it washes down with the rain, helping to cause the 230 oxygen-deprived “dead zones” that have proliferated along the U.S. coast. In the Chesapeake Bay, about one-fourth of the pollution that leads to dead zones can be traced to the back ends of cows, pigs, chickens and turkeys. … “We now know that we have more nutrient pollution from animals in the Chesapeake Bay watershed” than from human sewage, said J. Charles Fox, the EPA’s new Chesapeake czar. “Nutrients” is the scientific word for the main pollutants found in manure, treated sewage, and runoff from fertilized lawns. They are the bay’s chief evil, feeding unnatural algae blooms that cause dead zones. … But, according to Cornell University researchers, the amount of one key pollutant — nitrogen — entering the environment in manure has increased by at least 60 percent since the 1970s. … The law, however, has treated manure and other agricultural pollutants differently than pollutants from smokestacks and sewer pipes. The EPA does not set a hard cap on how much manure can wash off farms, instead issuing guidelines that apply only to the largest operations. There, the rules might limit how much manure farmers can spread on individual fields, for instance, or order them to plant grassy strips along riverbanks to filter manure-laden runoff. Even that level of regulation has only been in place since the 1990s. …
Manure becomes pollutant as its volume grows unmanageable
