by Nancy Carver Singleton

One Maine cattleman has built a sideline business of producing compost from slaughterhouse waste.

Disposal of this waste "offal" became a major issue for Maine meatpackers and slaughterhouses as renderers go out of business or their fees increase sharply -- from $2 to $20 a barrel.

The rendering industry has struggled following the Food and Drug Administration ban on using meat in feed for ruminant animals.

"We were getting a lot of phone calls saying, 'We have a problem! We don't have any alternatives! What can we do? Is there a solution?' " recalled Bill Seekins, agricultural resource management coordinator for the Maine Department of Agriculture.

They organized a meeting to identify options for slaughterhouses. Among those attending was Tom Campbell of Litchfield, Maine.

Seekins asked Campbell if he would compost offal on a commercial basis. "It has been an extremely interesting field to get into," Campbell said.

In August of 2001, Seekins and Campbell began developing the composting process.

The compost pad on Campbell's farm is a bunker silo most recently used as a silage pit. He hauled fill, excavated, removed walls and poured $7,000 of cement to construct a 100- by 100-foot (10,000-square foot) composting area. Horse bedding is used as the carbon source needed for composting.

Seekins designed a two-part composting system, preconditioning followed by turning.

For preconditioning, offal is spread over a one-foot thick bed of horse manure that is surrounded by a 12-15 inch berm of horse bedding. The berm prevents liquid from spilling onto the concrete pad.

This is a preconditioned pile of offal that has been opened after 20 days. There is no tissue left.

The offal is then covered with 18-24 inches of horse bedding. This keeps the offal contained in the covered berm until the soft tissue turns to liquid. Although there is some identifiable tissue after 14 days, the tissue is virtually gone by 20 days.

A new batch of offal is then added to the bedding material. It takes about two months to compost three loads of offal. After that, new bedding is used with offal and the former bedding is ready for its own composting process. "It looks like rich black earth," Seekins said.

Campbell forms small pyramids with compost on another portion of the concrete composting pad. Piles are started at different times and combined to make a windrow-like structure. Active management is needed, with the material turned a minimum of two to three times a week while checking to be sure the temperature reaches at least 131 degrees F. Turning aids the airflow needed to increase temperatures.

A loader covers offal. The offal is contained in a bermed bed of horse bedding to keep it from spilling on the cement pad below.

"We really watch the temperature as a guide," Seekins said. As the temperature drops, piles are turned less frequently. When the temperature is down to 108-110 degrees F, the composting process is complete. This stage takes about 8-10 weeks.

Then the material is ready for the curing stage, which will be 90 days to six months. Turning is less frequent then, perhaps every three to four weeks.

Campbell charges $12 a barrel of offal if he has to travel more than eight miles one way, and if the quantity is low or the slaughterhouse is an infrequent customer. For steady customers, the charge is $10 a barrel for pickup. If the offal is delivered to Campbell's farm, the charge is $5 a barrel.

In 2002 he started composting bones from slaughterhouses. Seekins explained that bones are more difficult to decompose. So they came up with a strategy to precondition the bones by putting them in a berm covered with bedding.

A pyramid pile is formed by pushing the preconditioned material up with a skid steer loader.

Campbell calls the process "shake-and-bake" with the bones stirred after they are buried. "I kind of roll it in horse manure and bury it with at least 10-12 inches of sawdust and horse manure. The blanket of horse manure buries any odors while it is cooking," he explained. This stage takes about 21 days.

After the tissue has decomposed, Campbell uses a grinder to break the bones into small pieces. They are put in windrows for one to two months until just compost remains.

Seekins said, "It makes a really nice rich compost material. It is fairly high in calcium and phosphorus, good for root-type plants such as potatoes or bulbs such as irises and tulips." The compost from bones will be marketed for the first time this spring.

The compost from offal is similar to any farm-based compost and can be used for gardens, flowers, lawns and turf.

During the off-season Campbell collects about 15 barrels of offal and/or bones a week. In the peak season -- October through January -- Campbell collects 100 barrels a week.

Composting works fairly well with Campbell's other farm businesses, though processing offal takes up "almost all my time" during the peak season.

Last October he attended the Maine Compost School, a week-long class held four times each year. "I would highly recommend it to anyone who is involved in composting," Campbell said. The school is sponsored by the University of Maine Cooperative Extension, the Maine Department of Environmental Protection and the Maine Department of Agriculture, Food and Rural Resources. Seekins is one of the school's directors and has taught sessions there since 1997. Students, which have included people from livestock operations, have come from 15 countries and a number of states. The cost is $495. More information is available at www.composting.org. ©