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Composting cows raises pollution concerns

A growing number of states allow farmers to compost the carcasses of cows, horses and poultry. Some environmentalists question whether it could lead to groundwater and surface water contamination.
Composting Carcasses
Dairy farmer Ken Nobis stands near his compost pile in St. Johns, Mich., on Nov. 9. The 10-foot-high, 50-foot-long heap consists of cow manure and the decayed remains of dead cows.James Prichard / AP
/ Source: The Associated Press

Dairy farmer Ken Nobis reaches into a tall mound of what looks like topsoil and grabs a clump, which he looks over and quickly sniffs before crumbling it.

The 10-foot-high, 50-foot-long heap that he's examining is a compost pile. Its humus is dark, rich and virtually odor-free — which is surprising, given that much of it consists of cow manure and the decayed remains of dead cattle.

Michigan recently enacted new rules that make it easier for farmers to compost animal carcasses.

A growing number of states allow farmers to compost the carcasses of horses, poultry and livestock. The agriculture industry says it’s a safe and economical way to dispose of dead animals, though some environmentalists question whether it could lead to groundwater and surface water contamination.

U.S. farms started using composting as a disposal method for dead poultry in the 1980s. Hog farmers later adopted the method, which more recently has been used to dispose of cattle and sheep carcasses.

"It breaks down a lot faster than I thought it would," Nobis said of the material in his compost pile. He has learned to frequently turn over the organic material with a front-end loader to better aerate it and allow the bones to break down more quickly.

The humus, which is rich in nitrogen, phosphorus and potassium, someday will be spread as fertilizer on Nobis' 3,000 acres of corn, wheat, soybean and alfalfa fields.

Sierra Club concerns
Lynn Henning, a factory farm watchdog for the Michigan chapter of the Sierra Club, said she believes the state's new composting rules won't sufficiently protect the environment. She served on the committee that wrote the regulations but said she's "not happy at all" with them.

Environmentalists believe there should be more oversight and certification of compost piles for dead farm animals. Livestock manure can contain antibiotics, growth hormones and chemicals, and should not be used as a bulking agent in the piles, Henning said. Enclosed structures should be required for all compost piles to protect them from weather, flies and wild animals, she added.

Compost piles should not be allowed near catch basins, streams or other areas vulnerable to potentially toxic runoff, the Sierra Club says. Piles should be required to be a set distance from neighboring homes, and groundwater test wells should be mandatory.

"You're looking at a lot of dead animals, and we need a better way of dealing with it," Henning said.

Michigan's new rules allow farmers to build open-air compost piles in their fields without a floor or a structure, as long as they do not exceed more than 20,000 pounds of carcasses during a year. Otherwise, producers are required to construct bases of concrete or other impermeable surfaces for their piles and drain any runoff into containment areas.

There are setback requirements intended to protect streams and wells from runoff. Farmers also are required to maintain records about what goes into their piles and must monitor moisture and temperature.

Few options for disposal
Historically, farmers haven't had many options when it came to getting rid of bodies or parts of bodies of their domestic animals. In Michigan, only a handful of landfills accept animal carcasses and parts.

The problem became more serious in recent years as Michigan's rendering industry — whose companies make glues, hair dyes and other products from animal remains — has nearly vanished. Rendering also is expensive, costing farmers up to $150 per animal for large livestock, said Kevin Kirk, a spokesman for the state Department of Agriculture.

Many farmers see composting as an economical and practical solution.

"Everyone sat around the table to develop these rules," says Ernie Birchmeier, a livestock specialist with the Michigan Farm Bureau, a lobbying group representing farmers. "We did the research, we did the homework and we came up with a strategy, a new management option for farmers to use that works for them and helps to protect the environment and utilize the nutrients in a more positive way."