Composting disposes of livestock without landfill costs
By STEVE BROWN
SOUTH PRAIRIE, Wash. -- RenÃ© Skaggs plunges a pitchfork into the compost pile, looking for a couple of chickens she buried there about six weeks before. Red twine she had tied around the carcasses' legs guides her work.
About a foot below the surface she finds the first chicken, or what's left of it: a few of the larger bones and some feathers. There's even less left of the second.
Skaggs, with the Pierce County, Wash., Conservation District, has overseen the demonstration project at the district's South Prairie Creek Preserve, a former dairy about 20 miles southeast of Tacoma.
"Notice how there's no smell aside from the regular compost smell," she said.
Putting meat or fatty substances into regular compost is generally a no-no, but for animal operations, whether commercial or self-sustaining, it can contribute to overall farm productivity.
"Any animal facility has mortalities. This is a way to use the material and make it safe to put on the ground," said Andy Bary, of the WSU Research and Extension Center in Puyallup. "It requires more oversight to get the compost to the desired temperature."
Specifically, he said, the temperature needs to be above 131 degrees Fahrenheit for a number of days, which depends on the size of the carcass.
"A chicken breaks down pretty quickly, as you saw. It's the same process, only longer, for cattle, sheep, pigs," he said. "The larger bones do break down, too -- it just takes longer."
Bary, in his position as scientific assistant in crops and soils, has demonstrated carcass and offal composting in workshops, showing farmers how the technique solves the problem of by-product disposal and prevents materials from going into the landfill.
As with any compost, he said, three principles are involved:
* Moisture content. A roof over the compost will help maintain even moisture.
* Temperature. This is monitored with a long thermometer.
* Protection from scavengers and pests. Having at least a foot of material covering the carcass is sufficient to keep scavengers from being attracted, he said. And the material is not turned often, as garden compost is.
The finished product is rich in carbon, nitrogen, potassium and phosphorus.
"Apply the material at agronomic rates," Bary said. "That's determined by nutrient analysis of the compost."
The high temperature is required to deal with any pathogens in the carcass, he said. Research is still under way to determine if that level of heat is sufficient to destroy the prions associated with bovine spongiform encephalopathy, he said. All pathogen reduction work is done by USDA researchers.
"I always encourage people to use those temperature standards as a minimum," Bary said.
He said he has no more workshops planned, but if there is sufficient interest, he will schedule more. His responsibilities also include organic nutrient management, cover crops and pastured poultry. He encouraged interested people to go online to the WSU-Puyallup Web site: www.soils1.org