Cow composting

Several studies from Washington State University Extension note that Washington dairy farmers must dispose of more than 24,000 carcasses annually and that on-farm composting allows for immediate, year-round disposal with minimal cost and equipment. Livestock composting, when done properly, also helps protect surface and groundwater resources while reducing pathogens and keeping valuable nutrients on farms, according to the WSU Extension studies.

The studies, by Caitlin Price, note that the use of composting jumped when rates for rendering also spiked. The state department of Ecology published guidelines for on-site composting of livestock mortalities in 2005, in response to a Senate bill.

The basics:

Carcasses should be placed on a minimum 2-foot deep layer of co-composting material, with no part of the animal closer than two feet from the edge of the pile.

The animals then should be completely enveloped in at least two additional feet of material with high carbon content, such as sawdust or animal bedding, to generate temperatures high enough to kill pathogens.

Internal temperatures at all points in the compost piles must be at least 131 degrees Fahrenheit for at least three consecutive days to kill any pathogens.

Compost piles should be at least 300 feet from any surface water or drinking water wells, should not happen in areas with seasonally high groundwater, and must have a system in place to collect leachate and storm water runoff.

Under Ecology’s guidelines, livestock compost used on site doesn’t require any special permits or notification to neighboring communities. But dairies must allow for regulatory inspections and take necessary precautions to control odors, protect groundwater and surface water, and prevent the compost from attracting flies or predators.