By Mary H. Wicks and Harold M. Keener
Inspiration strikes at unexpected times. Returning from a road trip to Missouri, a team of Ohio State University (OSU) researchers and extension educators had the “aha moment” that would form the basis of OSU’s mortality composting certification program. But first, some background . . .
In 1994, when the Ohio legislature approved composting as an on-farm option for disposing of dead animals, an OSU team, working with livestock producers, Ohio Department of Agriculture and USDA NRCS, was tasked with developing a certification course to ensure it was done correctly. Research and Extension faculty with expertise in livestock and poultry systems as well as composting scoured the literature, learning how other states were composting dead poultry and swine. A trip to the University of Missouri’s swine composting system provided more information.
Connecting the dots between his compost research and what he had learned about controlled decomposition of dead animals, Harold Keener characterized the latter as “above ground burial in a biofilter.” As the team discussed this concept and what they wanted to achieve, they focused on developing guidelines that allowed for flexibility and the ingenuity of farmers. They identified four criteria that needed to be met for any dead animal composting system: (1) protect ground and surface waters; (2) reduce the risk of spreading disease; (3) prevent flies, vermin and other nuisances; and (4) maintain good air quality.
This framework was used to develop Ohio’s Livestock and Poultry Mortality Composting Manual for the certification course. It provides guidelines based on best practices rather than a prescription and covers composting principles, site design, management, biosecurity, economic considerations, and more.
Composting is a natural process in which microbes decompose organic matter generally in the presence of oxygen. For the first stage of mortality composting, the whole animal is laid on top of an ~2-ft layer of organic amendment (e.g., sawdust, straw, stover) and then covered with another ~2-ft of amendment plus some recycled compost. The aerobic decomposition begins at the surface of the animal, while, internally, microbes in the animal’s gut decompose it anaerobically. This anaerobic decomposition is slower than aerobic and generates noxious odors. To minimize odors, the thick outer layer of amendment functions as a biofilter that removes odors and the compost pile is left unturned for 15 days to 6 months, depending on the animal size.
After turning, composting continues during the secondary stage and then stabilizes during the curing stage. A portion of the finished compost is recycled for use in a new first stage pile, with the remaining compost used as a soil amendment on the farm. Although mortality composting is a relatively simple disposal method and offers flexibility, it’s important to pay attention to details.
Glen Arnold, the manure management specialist with OSU Extension, recommends farmers inspect their mortality compost piles regularly. He cites low moisture content as a typical problem in indoor poultry composting systems. Low moisture will significantly slow the composting process. The covering materials should feel like a damp sponge and a temperature probe can be used to monitor the composting process.
Arnold notes that lack of sufficient amendments is often a problem. The amendment needs to be thick enough on the bottom to absorb leachate as the animal decomposes. It needs to be thick enough as a covering to prevent odors escaping or the site can attract rodents and other animals. The needed cover can also keep composting temperatures in the proper range even in the dead of winter.
Before composting mortality, Ohio regulations require that a farmer attend a 2-hour certification course. To date, over 5,500 Ohio farmers have attended the course. It is offered throughout Ohio by OSU Extension educators or can be taken online. The next course will be offered on March 12 in Wauseon. Details about it and the online course can be found at ocamm.osu.edu.
Mary H. Wicks and Dr. Harold M. Keener, Department of Food, Agricultural and Biological Engineering. Phone: 330.202.3533; 330-263-3856. E-mail: email@example.com; firstname.lastname@example.org. This column is provided by the OSU Department of Food, Agricultural and Biological Engineering, OSU Extension, Ohio Agricultural Research & Development Center, and the College of Food, Agricultural and Environmental Sciences