Compost piles can easily be disguised as mounds of discarded shavings or manure, such as those demonstrated above during a Penn State educational session. Photo courtesy of Robert Meinen.
As a horse owner and lover, nothing is more horrifying than reading stories about these magnificent, innocent creatures are being abused, neglected, and starved. Unless it’s the thought that after they die, the horses’ bodies are being callously dumped into piles of their own feces. How could anything positive come from such a repulsive notion?
But what about the act of organic composting itself? The assets – for the soil, as a fertilizer, to encourage sound environmental habits – are nearly as widespread now as they were for the victory gardens during the World Wars. Decomposed organic matter recycles its nutrients back into the earth to produce even richer soil while limiting the waste that overflows from landfills. This includes all organic material…eggshells, horse manure, and even deceased horses themselves can be sensibly composted and reutilized.
Ralph Waldo Emerson said that owning horses is not a gentle hobby. He's right—for all of the immense joy that accompanies horse ownership, an equal amount of pain follows when it is time for a beloved partner to cross the Rainbow Bridge. However, a practical, respectful, and legal plan for managing the body can help the transition and aid in peace of mind. Appropriately composting the remains continues to be the most highly recommended solution for its environment- and neighbor-friendly, cost-effective, and odor-reducing benefits.
When some people visualize a compost pile in their minds, they think of a rotting pile of garbage crawling with maggots and rats. This simply is not true. Robert Meinen, a Senior Extension Associate at Penn State and a Nutrient and Manure Management specialist, explained that “through the use of oxygen and carbon, composting accelerates the breakdown of biological material by the continuous actions of many varied microorganisms. A properly maintained compost pile will not smell, can be hidden from view disguised as a regular sawdust pile, and will not attract scavenging pests.”
The Smart Solution
With the deterioration of the rendering business within the last few years, horse owners have needed to look elsewhere to thoughtfully dispose of their deceased animals. Burial requires special equipment for a large animal carcass and may not even be possible in the winter when the earth is frozen. As well as being impractical due to cost, size, and the accompanying burning odor, cremation is environmentally unfriendly due to the amount of fuel required to incinerate the corpse and increases the ecological footprint. While some landfills accept large animal remains, they are often costly, require an abundance of paperwork, and would still need transportation to the site.
Discarding animals on the ground, exposed, and permitting them to be eaten or rot is neither legal nor professional. Carcasses containing veterinary drugs pose an additional threat to the wildlife and untreated soil. Composting is not only an economic option, but also an environmentally friendly management plan. According to a year-long study by Josh Payne, an Area Animal Waste Management Specialist and Adjunct Associate Professor at Oklahoma State University, composting animals that have been injected with narcotics used for euthanasia or pain relief will help the drugs, such as sodium pentobarbital, to rapidly dilute through mixing with carbonaceous materials. Barbiturates and non-steroidal anti-inflammatory drugs are often not completely absorbed by the horse’s body before the time of death, and these residual pharmaceuticals within the muscles and tissues can then cause secondary toxicosis by plundering wildlife. Sodium pentobarbital has been shown to degrade during the composting process so that by the time composting is finished (within six months) very low levels of the drug remain.
Through passively allowing a complex network of microbes to interact in a web of food and biology, composters are creating a nutrient-dense material for fertilizing non-table crops, re-vegetating barren areas, or even as a soil base for planting a memorial tree in honor of the deceased. Static pile composting of dead horses and livestock is a management practice that can fit into most livestock farms. The practice does require land to construct the compost piles, and takes from 6 to 12 months for the animal to naturally decompose.
Science and Biology 101
Firstly, check the local ordinances for regional composting. In Pennsylvania, the PA Domestic Animal Act defines the legal requirements for all deceased livestock procedures, including disposing of the carcass within 48 hours after the animal dies, preventing exposure of the carcass to all other living animals, including humans, and avoiding environmental, animal, or public hazards if transporting dead carcasses.
Compost locations are key: they must be set back in a well-drained area at least 200 feet from all bodies of water, including wells, sinkholes, and snow melt. This also includes shallow water tables where a large rain could stand for several days. Keep the pile away from concrete or slopes where any active cultures could travel, and separate from human and animal housing.
While manure can legally be used to compost equine remains, called “manure packing,” the most suitable component is an absorbent, carbon-based material such as shavings, sawdust, or wood chips. Most farms have shavings or sawdust already on hand, and after being used as bedding, are considered waste material.
The carcass is rich in nitrogen and the shavings rich in carbon, which provides a balanced diet for the microbial community that will conduct the decomposition. As a carcass begins to decompose, a large percentage of fluid will drain away from the body. Sawdust or shavings, because of their smaller particle size, contain ideal pore space to generally absorb the fluids better than mulch chips. Additionally, the carbon in shavings is more available to decomposing microbes because it has a greater particle surface area than an equal volume of chips. A base layer should be laid two feet deep, and then envelope the carcass an additional two feet deep in all directions.
If, after several days, there is a visible wet spot, bodily fluids are leaking and another layer of material is needed. The carcass may bloat and shift the sawdust, exposing wet spots or changing the height of the pile either taller or shorter. Exposed wet spots attract wildlife, flies, and produce odors. While oxygen is required to penetrate the pile for the decomposition process, it needs to be in a controlled fashion in conjunction with the carbon elements.
As the exothermic microorganisms begin to digest the animal, they will emit heat, which then in turn kills pathogens. While the animal is still warm, the good bacteria, fungi, and decomposing insects will begin to process the animal and the temperature will begin to rise even further. The desired bacteria require oxygen, which is pulled into the pile through the shavings. The heating of the carcass produces a ‘chimney effect’ with heat escaping through the top of the pile, and this in turn pulls fresh oxygenated air to the bacteria through the bottom edges of the pile. The opportunity for odor to appear is slim if the pile remains deep enough for odorous compounds to be captured in the shavings on top.
After three months, the flesh will have disintegrated and the pile can be mixed. With a front-end loader, scoop and turn the pile. The large parts of the body, including organs, muscle, hair, and bone might still contain wet anaerobic zones where oxygen is scarce and decomposition inefficient. Turning the pile introduces oxygen, allowing these zones to interact with the dry, carbon-based sawdust to be sure that the composting process is ensuing evenly. By integrating the anaerobic areas and pulling oxygen into those regions, a new spike in microbial activity is sure to occur.
By six months, the carcass should be fully decomposed, but there’s no harm in letting it sit for longer, in what is termed a ‘curing phase’. There may yet be a few large bones, as mature animal bones may take several seasons to fully break down, but those can easily be removed and crushed. The same compost pile can be used several times, as long as the carbon material absorbs liquids and allows internal air movement. The resulting carbon-rich material can be used on non-food crops, thinly distributed over large forested areas, or for other agricultural purposes such as spread for hay and corn.
Composting is the best way to truly recycle nutrients from a carcass and transfer them into the soil. It continues the circle of agriculture once the material is dragged back through the fields, and is a biologically complex process for simple carcass management.