Composting is a remarkably versatile process, and one that works for many kinds of organic material. A persistent challenge on farms is what to do with animals that die from natural causes, disaster, or a highly contagious disease. The USDA's preferred method for managing animal carcasses is to compost them.
The reason is straightforward: the traditional alternatives (like deep burial, landfilling, and incineration) carry environmental concerns like groundwater contamination, air pollution, disease management, cross contamination, and unusable land. Composting lets the carcass and all the organic matter around it return to the soil in an environmentally sound way. Follow proper best management practices, and what starts as a liability becomes a soil amendment, feeding nutrients back into the ground to be taken up slowly by plants over time.
I had the chance to assist in a state effort in 2016 after Hurricane Matthew while working for North Carolina Department of Environmental Quality. My team's job was to identify carbon sources so that Compost Subject Matter Experts (SMEs) could guide farmers on composting on site, and this included composting everything from the animals themselves to manures, bedding, and feed. Later in 2023 and 2024, through CMSE LLC, I assisted in the USDA in MI and CA when the bird flu impacted several poultry operations. My role was to evaluate, develop plans, guide contractors, and monitor composting piles built inside and outside barns.
The three-part method
1. Build the pile. Start with a coarse woody base with some fines mixed in. The base lets air move passively into the pile, and the fines absorb leachate. On top of that, build the core: the carcasses plus a proper mix of carbon material so microbial activity can thrive and break the material down. Finally, build a cap around the core using a mix of coarse and fine carbon. The cap insulates the core from outside temperature swings and acts as a biofilter to reduce odors.
2. Phase one. Take temperatures over a set period against a defined requirement — for example, 131°F for 3 days within a 14-day window. That temperature reflects the microbial activity in the pile, which along with heat is what deactivates disease and decomposes the carcasses. Once the requirement is met, turn the material into a new pile. Turning gives edge material a chance to decompose, breaks up pockets in the core, and gives everything another pass. It's a critical step.
3. Phase two. Take temperatures again over another window — this might also be 131°F for 3 days over 14 days. The exact time-and-temperature requirements depend heavily on what the state or federal government requires and on what you're managing. Once complete, you can cure the material further or till it into the soil to put the nutrients back to work.
The details that matter
Doing this properly involves more than the three steps above. You'll need to account for PPE (personal protective equipment), composting location, the type and amount of carbon available versus what's needed, and clear operator guidance. The USDA publishes strong resources on this topic — its APHIS Mortality Composting Protocol is the right place to use as the foundation for a site-specific plan. And it is highly recommended that you work with a Composting SME.
If you're facing a mortality composting question — routine or emergency — and want assistance, reach out.