VALUE OF BYPRODUCTS

COMPOSTING

What is Compost?

Compost is a product manufactured through the controlled aerobic, biological decomposition of biodegradable materials. The product has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds (in accordance with EPA 40 CFR 503 standards) and stabilizes the carbon such that it is beneficial to plant growth. Compost is typically used as a soil amendment but may also contribute plant nutrients. (AAPFCO definition, official 2018) Finished compost is typically screened to reduce particle size and improve soil incorporation. (US Composting Council)

The ingredients for composting include a proper balance of the following materials:

  • Carbon-rich materials (“browns”).

  • Nitrogen-rich materials (“greens”).

  • Water (moisture).

  • Air (oxygen).

Proper composting requires that the material “cook” at a relatively high temperature to break down the material and kill pathogens. As organisms decompose waste, they generate heat. Decomposition is most rapid when the temperature is between 90° and 140° F (32 - 60° C). Below 90° F (32° C), the process slows considerably, while above 140° F (60° C) most microorganisms cannot survive. Compost pile temperature depends on how the heat produced by microorganisms is offset by the heat lost through aeration or surface cooling. During periods of extremely cold weather, piles may need to be larger than usual to minimize surface heat loss. When composting high nitrogen wastes, like grass clippings in the summer, smaller piles and frequent turning are needed to provide oxygen and release excess heat. (Cornell Composting)

The microbes involved in the aerobic composting process ( Compost Microbes) fall into two groups:

  • Mesophilic those that are active in temperatures of (10 °C to 45 °C) and

  • Thermophilic active at 45°C to 70°C.

The psychrophiles a third group of microorganisms functioning at lower temperatures, in the range 10°C to 20°C (14°F to 68°F), do not play a significant role in hot composting but will be involved in keeping cold composting ticking over during in the winter in the UK and areas with a similar climate.

During the hot thermophilic stage, efforts should be made to ensure that the composting material is kept aerated and moist. Additional moisture should be added in the form of water or compost comfrey tea. Providing air and moisture are at levels that ensure biological activity is necessary to hold the high temperatures required to destroy weed seeds, pathogenic microorganisms, the eggs of parasites, and fruit flies, some of which have been shown to survive in composting material at temperatures as high as 57°C for several days. (Carry on Composting)

Carbon Nitrogen Ratio

To provide optimal amounts of these two crucial elements, you can use the carbon-to-nitrogen (C/N) ratio for each compost ingredient. The ideal C/N ratio for composting is generally considered to be around 30:1, or 30 parts carbon for each part nitrogen by weight. Why 30:1? At lower ratios, nitrogen will be supplied in excess and will be lost as ammonia gas, causing undesirable odors. Higher ratios mean there is insufficient nitrogen for optimal growth of the microbial populations so that the compost will remain relatively calm and degradation will proceed slowly. (Cornell Composting)

Articles & Resources

PUBLICATION

Composting Large Animal Carcasses

Texas A&M University — Texas A&M AgriLife Extension

PUBLICATION

Natural Rendering: Composting Livestock Mortality and Butcher Waste

Cornell University — Cornell Waste Management Institute

WEBPAGE

Mortality Composting

Cornell University — Cornell Waste Management Institute

GUIDE

Livestock Mortality Composting Protocol

USDA Animal and Plant Health Inspection Services

Photo courtesy of Cornell University - Cornell Waste Management Institute

PUBLICATION

Rotary Drum Composting of Poultry Mortalities

Mississippi State University — Extension

PUBLICATION

Livestock Mortality Composting: For Large and Small Operations in the Semi-Arid West

Colorado State University — Extension

PUBLICACIÓN

Compostación de Ganado Muerto: Para Instalaciones Grandes y Pequeñas en el Oeste Semiárido

Colorado State University — Extension

On-Farm Spotlight

Yakama Nation Farms

Washington-based Inaba Produce Farms share their on-farm composting project with Yakama Nation.

Read More

Photo Source: Yakama Nation Farms, Facebook Page.

Webinars

Byproduct Breakdown: Composting and Biodigestion for Meat & Poultry Processors

Composting and biodigestion of slaughter waste are increasingly being adopted as alternatives to landfill disposal. New developments in these technologies are making these technologies more readily usable for smaller meat and poultry processors.

During our one-hour roundtable conversation learn from experts leading the way in helping meat and poultry processors utilize composting and biodigestion to capture value from byproducts currently headed to landfills.

Watch Now.

Webinar FAQ.

Innovations in Waste Management for Meat Processors

Niche Meat Processor Assistance Network (NMPAN), Assured Renewables, & EcoDrum

 

Additional Resources