Animal agriculture is faced today with discovering innovative ways to dispose of livestock and poultry mortality. This need has been brought on by the disappearance of rendering plants, concerns over burial and ground water pollution, and the economic cost and other issues related to incineration.

 To address this need, the Ohio composting team was formed consisting of the following agencies and organizations:  

·         The Ohio State University Extension

·         Ohio Agricultural Research and Development Center

·         Ohio Department of Agriculture

·         Ohio Department of Natural Resources

·         USDA / Natural Resources Conservation Service

·         Ohio Environmental Protection Agency

·         Ohio Livestock Coalition

 In 1996, the workgroup published the Ohio Composting Manual and began offering certification training to producers. Mortality composting in agricultural operations is now a legal option for on farm disposal of swine and poultry carcasses in Ohio.  

The team recognized there is a need for on farm mortality composting of all livestock species since rendering plants are less available than before. A universal design procedure, based upon the animal body weight and poundage of daily mortality, was developed to size the primary and secondary composting volume requirements. In the fall of 1999 the Ohio Composting Manual will be revised and republished with the new design procedure. The relationship between the animal body weight and composting cycle times is illustrated below.

 
Figure: Animal Composting Cycle Time

Definitions

Primary cycle – The time period from when the animal is added to the compost facility until the body is decomposed, although some large bones may still exist. The primary cycle represents the time period needed for the compost to reach and maintain a temperature of 140° F for at least three days, and then cool to about 110°. The minimum primary cycle period is ten days. At the completion of the primary cycle the compost needs to be thoroughly mixed (turned).

Secondary cycle – The time period from when the compost is turned, reheats to 140° for at least three days and then cools to less than 110°. At the completion of the secondary cycle the compost should be stored for an additional 30 days for curing prior to land application. Also after completion of the secondary cycle, this compost can be mixed with fresh sawdust to be used in a new primary cycle.

Composting Method

The practices of composting animal mortality are simple. Recommendations by the Ohio Composting Development Team are:

1)      Construct a base from sawdust or acceptable amendment at least one foot thick. (More base may be needed for very large animals.) This base will collect liquids that are released during carcass decomposition. It also permits air and microbial action underneath the carcass. If liquids begin to leach out of the pile, spread sawdust (or suitable amendment) around the pile to absorb the liquids and increase the depth of the base when constructing new piles.

2)      Place a layer of carcasses on the sawdust base. A single layer of carcasses should be centered on the base and be spaced evenly across the base. Do not stack carcasses on top of one another. An exception is small animals such as fish or lab animals, where mortalities can be layered up to 4 inches thick. Four to six inches of amendment should be maintained between layers.

3)      Cover the carcasses with 1-2 feet (two feet in outside piles, one foot in enclosed bins) of damp amendment. This cover acts as the biofilter for odor control around the pile and insulates the pile to retain heat. Odors may be released when an inadequate cover is used or when it is too dry. The released odors may also attract scavenging animals and pets to the pile.

When additional carcasses are placed in the pile the following steps should be followed:

1)     Hollow out a hole in the amendment (in the one to two feet of cover material); while maintaining 4 to 6 inches of amendment over carcasses already in the pile.

2)     Place a new layer of carcasses in the pile.

3)     Cover new layer of carcasses with 1 to 2 feet of damp amendment.

More Information

Composting has been demonstrated to be an economical and environmentally sound method of mortality disposal.

The new manual should be available early 2000. For information on becoming certified in swine and poultry mortality composting, contact your local OSU Extension, Natural Resource Conservation Service (NRCS) or Soil and Water Conservation District (SWCD) office. For additional information on the new manual, contact:

Tammie Brown, Resource Mgt. Specialist, ODNR (614-265-6684, tammie.brown@dnr.state.oh.us

Michael J. Monnin, Envir. Engr., NRCS/USDA (614-469-6942, mike.monnin@oh.nrcs.usda.gov

Harold M. Keener, Agr. Engr., OSUE/OARDC/OSU (330-263-3865, keener.3@osu.edu