ROCK SPRINGS, Pa. — The death of a farm animal due to old age, premature birth or any other factor is unfortunate, but part of the circle of life. Keyword here is circle. Just because Bessie kicked the bucket doesn’t mean she’s done contributing to the farm.
If done properly, composting animals is a way to dispose of deceased animals while taking advantage of valuable resources, said Elizabeth Santini, a state veterinarian with the Pennsylvania Department of Agriculture Bureau of Animal Health and Diagnostic Services.
She presented this topic at Ag Progress Days, Aug. 18-20. Her talks concluded with a tour of the on-farm animal composting site, where Santini started a compost pile in early May with support from Penn State educators.
Santini said although some farmers may just “dump animals on the Back 40,” she strongly advises against this practice.
Doing so could spread diseases and poison wildlife, attract scavengers to the property and to the livestock and even contaminate the air, water and soil.
It also illegal, Santini said, as Pennsylvania law requires the proper disposal of animals within 48 hours of death. Failure to comply may result in fines.
Proper composting avoids these issues and takes advantage of the valuable resources in animal carcasses, Santini said.
Although composting is a relatively simple process, there are some important factors to consider.
The ideal carbon-to-nitrogen ratio is 20-30:1, meaning that for each animal (the nitrogen source) to be composted, farmers should use about 20 to 30 percent more carbon provided by plant materials.
Santini said this is not something farmers will measure directly, but it helps them to keep in mind the importance of choosing materials high in carbon.
Other factors include the free movement of air through the pile, moisture (50 to 65 percent), temperature (50 to 160 degrees Fahrenheit), pH level and the particle size of materials (should not exceed 1-2 square inches).
Farmers can use the “squeeze test” to assess the moisture content of the materials. A handful of materials should be just wet enough to make the hand feel moist.
Santini said a well-constructed pile will heat to an ideal temperature of around 130 degrees Fahrenheit.
Santini said sawdust is one of the best composting materials, but because of its expense, other options work just as well.
She said wood chips or shavings, chopped straw or cornstalks and old hay are all acceptable materials. Shredded leaves and manure — especially horse manure — are also good additions, as long as they are mixed with other materials to maintain the proper moisture and carbon content.
Santini said the composting location is just as critical as constructing the composting pile.
The compost should be in a location where it is easy to access with equipment such as skidloader or tractor. However, the pile should be away from public view and at least 200 feet away from a water source.
The composting process can take anywhere between six and 18 months, depending on weather, carcass size and the factors mentioned earlier. If done properly, Santini said composting piles will have no decomposition odor, flies, runoff or scavengers.
When composting cows it is not necessary to lance the rumen, but it will help speed the process and avoid bloat.
Although composted materials can be used to spread on fields for plants, it is recommended that the materials not be spread on pastures for grazing animals.
In terms of legal requirements, farmers do not need to acquire a license as long as they are composting their own animals on their own farm.
A license is required when composting someone else’s carcasses.
Santini recommends producers take the following steps when composting animals after identifying the proper location and materials:
1. Spread a base layer of composting material at least 24 inches deep. She said it’s important not to skimp on the base layer.
2. Place a single layer of carcasses on the base, allowing at least 6 inches between each animal.
3. Cover with another 24 inches of composting material.
Santini advised not to layer large animals on top of one another. However, farmers can layer small animal carcasses, such as pigs or chickens.
The entire pile should not exceed 8 feet in height and 16 feet in width, and it should be constructed lengthwise on a 2 to 4 percent slope.
Penn State’s composting Web site
Cornell’s composting Web site