Composting Cattle Carcasses
by David B. Fischer and Ted L. Funk
TAKE HOME MESSAGES
- Illinois dairy producers are allowed to compost dead animals under the new rule.
- Compost site must be located at least ¼ mile from nearest residence that is not a part of the facility.
- Decomposition of a mature dairy cow will take approximately 6 to 8 months.
- Illinois composting rules can be reviewed at: http://www.agr.state.il.us/Laws/Regs/DeadAnimalDisposalReg.pdf
Illinois cattle, sheep, and goat producers can compost dead animal carcasses under Illinois Department of Agriculture rules that recently took effect in October 2004. Swine, poultry and fish producers had been permitted to compost for some time. Currently, cattle carcass disposal is most commonly accomplished through rendering services. However, after the concern of Bovine Spongiform Encephalopathy (Mad Cow Disease) and the prohibiting of feeding bovine animal-derived protein to cattle, rendering costs have risen which prompts producers to look for other options. Other carcass disposal options are either burial or incineration. With incineration being costly and highly regulated, burial was the only other viable option until now. If managed properly, composting cattle carcasses can be an environmentally safe and economically feasible method to dispose of on-farm mortalities. However, if not properly managed composting can be a problem leading to regulatory implications. Let’s review some of the questions producers may have about the composting process.
WHO REGULATES CARCASS COMPOSTING IN ILLINOIS?
The Illinois Department of Agriculture Bureau of Animal Welfare is the regulatory authority for composting carcasses, and for the Dead Animal Disposal Act in general. Illinois EPA and Illinois Department of Public Health may become involved in investigating complaints about composters.
DO I HAVE TO REGISTER MY COMPOSTING SITE WITH THE DEPARTMENT?
Composter site registration is not required at this time.
WHERE CAN I SET UP MY COMPOSTING SITE?
The site must be located at least ¼ mile from your nearest neighbor’s residence and it must be placed on a suitable location with adequate diversions to prevent surface water from draining to the compost pile. Avoiding water from entering the pile is important in order to give the producer the control over the moisture content of the compost pile. Also, it is essential to keep composter contents from leaching to groundwater or running off to surface water.
WHAT TYPE OF A COMPOST FACILITY CAN I CONSTRUCT? MUST IT BE A ROOFED CLOSED-IN FACILITY?
A concrete slab with treated lumber bin walls and a roof is preferable. Roofing provides the producer with more control to regulate the amount of moisture during both wet and dry weather, which is important for proper composting. Also the solid flooring and surrounding area allows for easy access to turn the pile or for adding materials to the pile during wet, muddy conditions. The facility could also be as simple as setting large round hay bales end to end on a solid limestone or geotextile base making three-sided rectangular bins. The bale compost setup is not recommended as a permanent installation.
You need at least two composting bins, one primary and one secondary. The best way to get the carcass compost to reheat and finish composting is to move the pile over into another bin.
HOW BIG SHOULD MY COMPOSTER BE?
The size depends entirely on the amount of mortality you expect per year. The minimum bin size for a single cow carcass is about 10 feet square and walls five feet high (double it because you need two bins).
WHAT TYPE OF ORGANIC MATTER CAN I USE TO SUPPLY THE CARBON SOURCE NEEDED?
Sawmill sawdust is best because of the fine particles that can fill-in around the carcass. Mixture of finely chipped wood, chopped corn cobs, straw, and/or chopped corn stalks will work. The material must be absorbent, maintain its structure to allow the pile to “breathe”, and be a good carbon source for the composting organisms. Wheat straw by itself is not good, as it packs down too tightly. Whole corncobs have too little surface area and need to be chopped or ground. Up to 50 percent of the finished compost can be recycled back to the primary bin. Experience with composting other animal species shows that you will need a ratio of about 3.7 cubic yards of sawdust per 1000 pounds of carcass composted. You should keep a good supply of carbon source on hand, and you may need to keep it covered so you can control the moisture content.
WHAT OTHER ITEMS DO I NEED?
A compost thermometer with a 36 inch stem is vital for monitoring temperatures and is required by the regulation. You will need a method to get water to the composter to maintain the right moisture. A bucket loader for turning the compost after the first “heat” cycle and for loading out the finished compost is also essential for managing the operation.
WHAT IS THE COMPOSTING PROCEDURE FOR PROPER DECOMPOSITION OF ANIMAL CARCASSES?
Two composting cycles are needed to complete the decomposition. The carcass may need to be prepared or “processed” to allow for maximum exposure to air, moisture, nutrients and carbon. Animals weighing more than 300 pounds compost faster with some processing including slicing the large muscle areas and opening the thoracic and abdominal cavity. Lancing the rumen will reduce tendency of the carcass to bloat, may reduce odor problems, and it will make it easier to keep the carcass covered with carbon source. The carcass provides the nitrogen source and some moisture, while you will add the carbon source. The moisture content of the compost is important and should be maintained at 40 to 60 percent. Prepare the pile with at least 12 inches of sawdust or other carbon source on the base followed by placing the animal on the sawdust. Large animals should be laid with the backbone down. The animal carcass must be covered totally with at least 12 inches of sawdust or other adequate carbon source (more is better). You will need to add carbon source material to the pile periodically as the carcass breaks down (check the composter as part of your daily routine).
Monitor the temperature of the pile using the 36” thermometer, and record the temperatures and date. Composting temperature in the center of the pile should reach 130-150 degrees F. for an extended period. Three or four months after the initial loading, use a bucket loader to move the pile into the secondary bin. Add water if necessary. Check the temperature in the secondary bin to make sure it re-heats. Following the second heat cycle (another 2 to 4 months) the compost is ready to spread on a field. You may have some large bones remaining, but they can be put back into the primary bin for further breakdown.
WHAT PROBLEMS CAN I ANTICIPATE WITH COMPOSTING?
Odors: As long as you add sufficient carbon source to the pile and keep the carcass covered, odors should not be a problem. You may have odors emitted briefly when you turn the primary bin and move its contents to the secondary bin.
Scavengers: You may have to fence the poster, but usually keeping the carcass well covered with carbon source is sufficient to keep odors down so that digging scavengers are not attracted.
Leaching and runoff: Grade around the composter to keep clean storm water away from the bins. Don’t overwater the compost. Use proper type and sufficient amounts of carbon source materials.
Insufficient composting rate or low temperatures: Adjust moisture as needed. In winter it is difficult to “jump-start” decomposition of a cold carcass.
HOW DO I DISPOSE OF THE FINISHED COMPOST PRODUCT?
Applying it to the field with a box type manure spreader is recommended because animal carcass compost is a very good source of fertilizer for the crops. It should not be given or sold as compost for off-farm use. The compost N, P, and K should be considered part of the nutrient management plan for the field.
WHERE CAN I GET MORE INFORMATION ON COMPOSTING?
NRCS Ag Waste Management Field Handbook (see http://www.wcc.nrcs.usda.gov/awm/awmfh.html).
Illinois Department of Agriculture, Illinois Dead Animal Disposal Act and Code. (see http://www.legis.state.il.us/commission/jcar/admincode/008/008000900001100R.html). There are also several web sites at state land grant universities.
WHERE CAN I BUY A COMPOST THERMOMETER?
You can expect to spend about $90-100. Look for 36 inch long, 5/16 inch diameter stem. Two choices (about the same price) are listed:
- Reotemp heavy duty (5/16” by 36”) windrow composting type. www.reotemp.com, phone 1-858-784-0710.
- Omega heavy duty (5/16” by 36”) windrow composting type. www.omega.com/temperature, phone 1-888-TC-OMEGA.