Progress With Composting as a Means of Swine Mortality Disposal

Livestock Update, January 2002

Allen Harper & Mark Estienne, VA Tech Tidewater AREC

Recently, on November 13, over 50 swine producers, nutrient management planners and Department of Environmental Quality inspectors converged on the Virginia Tech Tidewater AREC to participate in a half-day swine mortality disposal workshop. The workshop emphasized composting as a means to effectively dispose of normal mortality that occurs on hog farms. Some producers made the trip to southeast Virginia from as far west as Bedford, Buckingham and Halifax Counties. The strong interest in this topic and the willingness of producers to make long road trips to participate signifies the importance of this problem on working hog farms.

Even on well-managed farms with high herd health status, a small percentage of hogs and pigs will die. Traditional methods of dead hog disposal, including on-farm burial, on-farm incineration and transport to rendering plants, each have certain limitations. Burying hogs requires significant time, labor and digging equipment if done properly. Regulatory agencies are now discouraging burial of dead hogs following the recent discontinuance of burial as a means of dead poultry disposal for ground water protection reasons. On-farm incineration requires specialized incinerator equipment and also requires a separate permit from the Department of Environmental Quality. Transport to rendering plants increases health and bio-security risks when people and transport vehicles move to and from hog farms and the rendering plant. And some hog farms are just too distant from a rendering plant to justify this method of disposal.

Is composting right for your farm? Composting involves combining and fully covering nitrogen-rich hog carcasses with carbon-rich materials such as wood chips, saw dust, chopped straw, or peanut hulls. When the mixture is prepared to contain adequate air (oxygen) and moisture (about 50% to 60% moisture), thermophilic bacteria grow and cause increased temperatures (130 to 160 F) and rapid breakdown of the carcasses. Finished compost is a stable mixture of organic material that can be incorporated into a nutrient management plan and applied to cropland.

Experience with composting in other states and our demonstration work here at the Tidewater AREC indicate that composting is a viable means to dispose of dead swine that routinely occur on hog farms. Small pigs can be composted quite rapidly and in that regard are similar to composting dead birds on poultry farms. Sows and larger market hogs require more time, as much as 3 months in a primary composting phase and as much as 3 months following turning for a secondary composting phase. A few bones may remain when composting larger hogs but this material is usually easily broken and crumbled.

Initial investment will depend on the size and type of composting facility that is put in place. In Missouri, some producers have been successful in preparing temporary composting structures using large round bales to form open-front "bins" containing sawdust and dead pigs. Such a structure would have a relatively low initial investment cost. But a well-planned roofed structure with multiple bins allows better control of moisture conditions and the overall composting process. The demonstration unit constructed at TAREC contains 8 bins that are 5 _ by 8 by 5 feet in volume. This small unit would accommodate a finishing farm producing 3500 market hogs annually. It was constructed for a cost of approximately $8,000 including all building materials, delivery of ready-mix concrete for the floor, and extension of electricity and water service to the building. Larger hog operations would require a larger composting unit. An effort is currently on going to make state cost-share funds available for construction of swine mortality composting facilities similar to that available for poultry composting units.

Other equipment needed would include a front-end loader or similar implement for loading large hogs and turning compost. A means of mechanically spreading the finished compost onto crop fields would also be needed.

Producers who recognize the principles behind effective composting and plan accordingly can employ the method successfully. The following table summarizes general procedures for successful composting of swine mortality. For more detailed information on setting up a composting process to dispose of hog farm mortalities, contact Allen Harper by phone at 757-657-6450, ext 106 or email at alharper@vt.edu.

General Operating Procedures for Successful Composting of Swine Mortality.

Site for composting	Convenient to hog buildings. Access for loading, turning and unloading. At least 100 ft. from wells. Safe from water courses, other sensitive areas.
Sizing of compost unit	Primary bins: 20 cu. ft. per pound of estimated average daily mortality. Secondary bins: equivalent space as primary bin space. 5 ft. maximum pile depth. Bin size appropriate for full coverage of hogs (suggest 5 1/2 x 8 ft. min. for market hogs; 7 1/2 x 10 ft. min. for sows).
Management (Primary bins)	Minimum of 12 inches of absorbent bulking agent for base layer. Some "active" bulking agent around the first layer of carcasses helps get the process started. Place carcasses so that they are at least 8 inches from bin walls and from each other. Add water to carcasses and bulking agent if the material is dry. Be sure bulking agent is in full contact with all surfaces of the pig. Slicing thick muscles on large hogs may improve composting action. Fully cover all carcasses immediately with at least 12 inches of bulking material. Do not place carcasses on pile with intentions of returning later to cover. After three days check temperature with probe thermometer. Internal pile temperature should exceed 130 F for 2 weeks for pasteurization. After about 2 months for small carcasses and about 3 months for large carcasses, the pile should be ready to turn and initiate a secondary composting phase. A shallow layer of dry bulking material on top of the pile will help decrease fly activity.
Management (Secondary bins)	Turning the pile into a secondary bin should reinvigorate the composting process. Temperatures should rise. If the material has dried during the primary composting phase, some water addition may be needed. A shallow layer of dry bulking material on top of the pile will help reduce fly activity. After 2 to 3 months in the secondary phase, compost should be ready for land application. When large hogs are composted expect to see some skull and large bone pieces remaining. Some of the remaining secondary compost material may be recycled into a new primary composting bin (up to 50% of the new primary mixture).
Troubleshooting	Internal temperature fails to increase above 130 F and remain elevated for at least 2 weeks: Check for poor carcass placement, inadequate aeration inside pile, excessively wet compost or excessively dry compost. Compost too wet: Turn and add dry bulking agent. Compost too dry: Turn and add water to bulking agent. Excessively high pile temperature (> 160 F): turn and reduce pile depth. Excess fly activity or odor: Check for protruding carcass parts or shallow coverage. Correct by adding proper coverage. Check for seepage and correct as needed. Check temperature and insure that composting activity is occurring in the pile. Small amount of seepage: Correct carcass placement in future. Have adequate bottom layer of bulking agent to absorb drainage seeping down through pile. Large amount of seepage: Turn and add bulking agent.

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