With reports of barn fires in the news recently, the Iowa Pork Industry Center has gathered some resources about pit foaming to share with producers.
Manure pit foaming poses a serious fire and explosion hazard. Foam traps methane gas at extremely high concentrations. When foam is disturbed, methane can be rapidly released into the barn, creating the conditions for a flash fire if an ignition source is present.
Why Foam Is Dangerous
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- Foaming manure can produce up to 3× more methane than non-foaming manure.
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- Methane concentrations inside foam have been measured as high as 700,000 ppm (explosive limit ≈ 44,000 ppm).
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- Disturbing foam during pumping or agitation can overwhelm ventilation systems.
SAFETY ALERT: Never disturb pit foam without adequate ventilation and removal of ignition sources. Flash fires can occur even in well-ventilated barns.
Graphic 1: Fire Triangle- Fuel (Methane), Oxygen (Barn Air), Spark
Illustrates how methane released forms foam, combined with oxygen and an ignition source, leads to flash fires.
Why Some Barns Foam and Others Don’t
Foam forms when high methane production combines with particles and microbial byproducts that stabilize bubbles:
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- Methane production: Driven by manure solids and microbial activity
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- Bubble stabilization: Fine particles and microbial “goo” keep bubbles from breaking
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- Microbial community: Strongly influenced by diet and manure history
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- Diet: Higher fiber diets (including DDGS) increase foaming risk
Graphic 2: Manure Foam Science Diagram
Shows methane bubbles rising, stabilized by fine particles and microbial compounds.
Key Safety Practices
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- Maintain minimum ventilation at all times, including empty barns
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- Ensure uniform air distribution—not just total airflow
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- Eliminate ignition sources when foam is present
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- Do not rely on opening doors or curtains alone to reduce risk
If You Have Active Foam Right Now
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- Increase ventilation immediately.
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- Eliminate ignition sources.
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- Delay agitation or pumping when possible.
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- Contact your extension specialist or manure professional.
Graphic 3: Ventilation After Foam Disturbance
Demonstrates how methane release can exceed ventilation capacity after foam disruption.
Managing and Reducing Foam
Diet Management:
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- Review fiber levels with a nutritionist
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- Reduce high-NDF ingredients when possible
Manure Solids Management:
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- Thorough agitation and solids removal lowers methane potential
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- Improved solids removal helps shift microbial communities over time
Foam Treatments:
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- Ionophores (e.g., narasin) can reduce methane production when applied correctly
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- Treat chronic foaming barns strategically
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- Surfactants may offer short-term relief but can worsen foaming long-term
Graphic 4: Foam Treatment Toolbox
Icons representing diet, solids management, ventilation, and targeted treatments.
The Bottom Line
Pit foaming is preventable and manageable. Understanding the science behind foam, and taking proactive steps, can significantly reduce fire risk and protect people, pigs, and facilities.
Additional Resources
For research-based guidance, visit the Iowa Manure Management Action Group (IMMAG) through Iowa State University Extension and Outreach.
Additional information can also be found at the IPIC website.
The graphics included in this email are part of the “Manure Foam: Science, Safety, Ventilation, Treatments” document created by IMMAG.
The Talkin’ Crap Podcast offers information on pit safety and foaming in the following episodes:
- Foaming at the Pit: Causes, Consequences, and What We’ve Learned (episode 18)
- Harvest Hazards: Manure Management and Farm Safety (episode 19)
For more information, contact your regional swine specialist.
