Composting: In-Vessel/Drum
alternative practice names:
Mechanical Composting; Drum Composting; Active Composting; Bedding Recovery
In-vessel or drum composting is an intensive aerobic composting process that utilizes a rotating drum to continuously move and tumble the mixture in the drum to increase air circulation and achieve uniform heating. This method promotes and accelerates decomposition by microbes by controlling temperature, moisture, and aeration. The enclosed system lessens gas and odor release and reduces pests while ensuring consistent conditions for microorganisms to break down waste efficiently, resulting in high-quality compost in a shorter time than traditional composting methods. The treatment provides a homogenous finished product that can be used as bedding and is generally free of most pathogens.
In-vessel composting generally integrates two technologies, solids separation and drum composting, to improve operational efficiency. In step one, recycled manure solids (RMS) are captured after raw slurry goes through a screw press, slope, or vibrating screen separator with rollers and typically comes out at around 30-35% dry matter. A conveyor feeds the RMS onto a conveyor belt that feeds into a rotary drum composter. In step two, the solids are dried in a composting drum for 1-3 days, operating at approximately 70°C. The drum uses continuous mixing and aeration to reduce humidity, odor, and pathogens and improve the consistency of the compost.
When used, in what regions in the U.S. is the practice found:
Northwest, West, Upper Midwest, Southwest, Northeast, Southeast
FARM SIZE
When used, typically found on farms of the following sizes:
Over 500 cows

Practice Benefits
Labor efficiency: Mechanical automation reduces labor by streamlining aeration and mixing, enabling quicker and more consistent composting of large manure volumes with minimal manual intervention.
Revenue potential: Composted manure solids can be sold as a valuable soil amendment, providing farms with an additional income source.
Odor reduction: Drum composting reduces odors by effectively decomposing organic matter in a controlled environment, minimizing the release of unpleasant compounds.
Volume reduction: In-vessel systems reduce manure volume by 10–15%, which lowers transportation and storage costs.
Faster processing time: Drum composting accelerates the composting process by maintaining optimal conditions for microbial activity, allowing manure to decompose more rapidly than in traditional composting systems.
Weather independence: Located indoors or under cover, these systems are protected from weather fluctuations, ensuring consistent composting conditions.
Space efficiency: Drum composters require a smaller footprint compared to traditional composting, making them ideal for farms with limited space.

Implementation Insights
Site-specific or Farm-specific requirements

Bedding practices: The practice will be more financially advantageous for farms wanting to use composted manure solids as bedding.
Required Capital Expenditures (CapEx)

In the most basic terms, a drum compost system includes the following components:
Separator: The technology requires either a screw press, slope, or vibrating screen separator with rollers.
Auger or conveyor: A belt conveyor or auger feeds the RMS into the rotary drum composter.
Rotating drum: This accelerates the drying process and leads to a modest reduction in moisture and a significant reduction in pathogens.
Ventilator: A ventilator or fan is required to regulate the aerobic process.
Control system: This will allow for temperature measurement and airflow control.
Other potential related expenses include:
Concrete slab floor: Installing a concrete slab floor can help accommodate the management, loading, and unloading of equipment.
Water: A water line and hose will allow for the addition of moisture as needed.
Power source: Access to a 3-phase power source is required.
Storage: Creating a dedicated area for the required bulking agent can improve efficiency.
Roof: A roofing system can be used to cover equipment and protect the operation from precipitation and cold temperatures.
Required Operational Expenditures (OpEx)

Labor: Some trained labor is required to monitor the bin, implement appropriate action promptly, and maintain the equipment.
Power: Operation costs vary widely across farms, ranging from $8,000 to $20,000 per year in parts and maintenance, plus electricity usage. Modern units draw about 50 amps when fully operational.
Carbon bulking material: This is needed to maintain pile carbon to nitrogen balance and add porosity.
Implementation Considerations

Cycle monitoring: Monitoring the compost cycle is critical to a successful operation.
Carbon: If not enough carbon material is added to the bin, the mixture becomes dense and not porous. A carbon-to-nitrogen ratio of 25-40 is necessary to produce a desirable compost product.
Moisture: Moisture content needs to be maintained so microorganisms remain active. If the temperature is too low, the compost becomes too dry and inactive.
Temperature: The temperature must be monitored to ensure the desired temperature (130-170 degrees) is maintained for at least three days for proper treatment.
Time: If material is processed too quickly, the mixture will not become mature compost.
Financial Considerations and Revenue Streams
PROFIT POTENTIAL
Producers commonly allocate approximately 60% of the RMS for bedding purposes, while the remaining 40% presents an opportunity for sale to other producers. This surplus material is often sought after for bedding or sold, with the nursery industry being a common buyer, where it is frequently blended with potting soil.
FEDERAL COST-SHARE PROGRAM
Funding is available for this practice through USDA's Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP).
Related EQIP Practice Standard: Composting Facility (317).
Notes:
Check with the local NRCS office on payment rates and practice requirements relevant to your location.
To quality for EQIP funds, the dairy is required to obtain a Comprehensive Nutrient Management Plan (CNMP) to guide practice implementation.
FINANCIAL RESOURCES, TOOLS, AND CASE STUDIES
Additional Resources
► See the Newtrient Solutions Catalog to learn more about Composting and related solution providers.
Article: Aerobic Composting Affects Manure's Nutrient Content (Northeast Dairy Business)
Article: Exploring Different Composting Options (Manure Manager)
Book chapter: NRCS National Engineering Handbook (NEH) (Title 210), Part 637, Chapter 2, “Composting.” (USDA-NRCS)
Handbook: On-Farm Composting Handbook (NRAES 54) (Cornell University)
Report: Manure Treatment Technologies (Chesapeake Bay Program)
Webinar: Dairy Composting: Unlocking Conservation Innovation Grant (CIG) Insights (Newtrient)

Environmental Impacts
MAY REDUCE FARM GREENHOUSE GAS FOOTPRINT
In-vessel composting can reduce methane emissions when manure solids are diverted from traditional anaerobic lagoon or liquid/slurry storage systems and managed aerobically. The prerequisite practice of Coarse Solid-Liquid Separation removes coarse and fine manure solids from liquid/slurry manure storage, thereby lowering the amount of organic matter and carbon available for methanogenesis. This results in lower methane production potential.¹ In-vessel composting keeps the process aerobic, limiting the conditions necessary for denitrification and reducing nitrous oxide emissions during the active composting phase.²
See research highlights below:
Fillingham et al. (2017) found that the total greenhouse gas (GHG) emissions (CH₄ + N₂O) from solid separation, active composting, and storage are substantially lower on a CO₂-equivalent basis than conventional liquid manure storage.
A life cycle assessment of dairy milk production on a farm in Ontario, Canada, found that using an active composting system reduced the carbon footprint of milk production by 36%, from 1.92 to 1.23 kg CO₂e per kg of fat-protein corrected milk (Guest et al. 2017).
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¹See Manure Separation: Coarse Solid-Liquid Separation.
²N₂O emissions may increase during the storage of composted material if conditions become anaerobic; the overall N₂O emissions from the combined processes (solid separation, composting, and storage) are still lower than those from traditional liquid manure storage.
Note: Trade-offs with NH₃ Emissions
Fillingham et al. (2017) found that while CH₄ and N₂O emissions are reduced, NH₃ emissions can increase during the continuously turned composting process. This is because the aerated composting conditions raise the temperature and pH, which shifts the equilibrium between NH₄⁺ and NH₃, leading to higher NH₃ volatilization. NH₃ is an indirect GHG and poses health risks.
Note: Variable Impacts of the Use of RMS Solids as Bedding
Using manure solids produced on the farm for bedding eliminates the emissions associated with sourcing and transporting sand or other organic bedding materials. Fillingham et al. (2017) found that the use of composted manure solids as bedding reduced total GHG emissions (CH₄ and N₂O) compared to traditional liquid manure storage, though NH₃ emissions were higher during active composting.
A systems-LCA approach is essential for accurately modeling the full impact of bedding choices on GHG emissions, as it accounts for interactions between bedding materials, manure management, and broader farm practices (see Bedding Management).
REFerences
EPA. (n.d.). Practices to reduce methane emissions from livestock manure management (AGSTAR). Environmental Protection Agency.

Alignment with FARM Program
FARM Environmental Stewardship (ES) V2-V3 Alignment
FARM ES Version 3 offers composting as a manure management data input. Users can specify if they are doing intensive windrow, passive windrow and static pile.
Contents
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
In-vessel or drum composting is an intensive aerobic composting process that utilizes a rotating drum to continuously move and tumble the mixture in the drum to increase air circulation and achieve uniform heating. This method promotes and accelerates decomposition by microbes by controlling temperature, moisture, and aeration. The enclosed system lessens gas and odor release and reduces pests while ensuring consistent conditions for microorganisms to break down waste efficiently, resulting in high-quality compost in a shorter time than traditional composting methods. The treatment provides a homogenous finished product that can be used as bedding and is generally free of most pathogens.
In-vessel composting generally integrates two technologies, solids separation and drum composting, to improve operational efficiency. In step one, recycled manure solids (RMS) are captured after raw slurry goes through a screw press, slope, or vibrating screen separator with rollers and typically comes out at around 30-35% dry matter. A conveyor feeds the RMS onto a conveyor belt that feeds into a rotary drum composter. In step two, the solids are dried in a composting drum for 1-3 days, operating at approximately 70°C. The drum uses continuous mixing and aeration to reduce humidity, odor, and pathogens and improve the consistency of the compost.
Practices and technologies
Composting: In-Vessel/Drum
alternative practice name:
Mechanical Composting; Drum Composting; Active Composting; Bedding Recovery