Silage Season Safety for Horizontal Silos

Feeding and unloading from a horizontal silo–bunker or pile–is an activity that happens through much of the year. These are some potential hazards you can be exposed to year-round. 

Dust and Farmer’s Lung

  • Silage is often not very dusty, but when it is, it’s usually because of poor storage or initial harvest conditions. Of greatest concern are dusty silage, haylage, or stored hay that has gotten moldy and has easily released mold “spores” which create dusty conditions.

    Diagram explaining the parts to a NIOSH N95 Respirator.

    N95 Respirator Infographic from CDC-NIOSH

  • Depending on a person’s health status, mold spores in dust can cause severe health effects. For some people, dust and mold spore exposure can cause an illness referred to as farmer’s lung or one called silo-unloaders syndrome.  Farmer’s lung is especially a risk for people who have had allergies, asthma, or other sensitivities.  Individuals prone to farmer’s lung should avoid these exposures.  If you’re concerned, check with your family doctor or other health care professional.
  • Tight-fitting dust NIOSH approved and certified “N-95” respirators, commonly referred to as dust masks, are recommended for work around many types of dust on a farm. Make sure any respirator fits well and all workers are in good health before they use a respirator.  Safety and health standards require a doctor’s “okay” before a person uses a workplace respirator because of the additional stress it places on the lungs and heart.  It’s impossible to use a dust respirator and get a proper seal if the person who wears it has a beard or other facial hair. We strongly recommend that any respirator be used within the framework of carefully-designed respiratory protection policy and program.

Machines and Equipment Used for Feeding

Silage Defacer – Involved in New York Death, 2005. Photo from NIOSH-CDC

There was a high profile death about 14 years ago.  It involved a young man, 18-years old.  He started his early morning on a modest, family-run dairy farm.  Safety had been emphasized over and over on this operation. It was cold. The man started the tractor and raised the defacer about four-feet off the ground.  For reasons unknown, he engaged the defacer with the hydraulic lever and climbed off the tractor with everything running.  Nobody knows exactly what happened.  From the scene investigation, it appeared that he walked around the right-hand front of the tractor. In doing so his jacket got caught on the rotating outer edge of the defacer.  It snagged him badly enough that he began to rotate with the spinning unit. His uncle heard this happening.  He saw the situation and shut off the tractor. He cut the victim’s clothing loose and called for help.  While he waited for the ambulance, he tried to give CPR. By the time the sheriff arrived, the victim was dead.

Horizontal silos –bunkers and piles – present special hazards for feedout in part due to the machinery and equipment used.

  • Big equipment –loaders, tractors, trucks– is one hazard.  The area around a horizontal silo can be a busy, confusing, and unsafe place.  For the large equipment operators, it can be hard to see people or other machines operating in the area. Employees need thorough training in safe operation.  Visitors and kids must be kept well away from the “feedout” area.
  • Silage ‘defacing’ equipment is another hazard for entanglement as noted in the situation above. 
  • Do NOT get off a machine with parts moving or power-engaged.  It’s just too risky.

Avalanche and Collapse Hazards

  • Overhangs in bunkers and piles are another feedout safety concern. Undercut silage ledges can avalanche and trap a person under several thousand pounds of silage. Even a perfectly flat feedout face of a horizontal silo that appears stable can collapse, leaving a person buried underneath.
  • It is recommended that a person stays back from the front face of a bunker or pile at a distance of at least three times the height of the front face to avoid being engulfed by an avalanche.   If you’re looking at a front face that’s 15 or 20 feet high, you need to keep a distance of 45 or 60 feet away from the face. 
  • When a silage “sample” needs to be collected, scoop up some silage in a loader, drive the loader away from the avalanche zone, and then take your sample from the loader bucket.
  • Loaders can be equipped with heavy-duty bars or mesh around the operator’s station to protect the operator if a pile collapses onto the machine.

Again, the farm is a potentially dangerous, industrial workplace. ALL who work on your operation need this understanding as well as the knowledge and tools to do their work safely!

This information has been revised material developed to support a series of corn silage harvest-related podcasts that will be posted by colleague Liz Binversie of Brown County, UW-Madison, Division of Extension.


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