Proper moisture at baling is the key to preventing hay fires

By Krishona Martinson, University of Minnesota Extension

Moisture content of hay at time of baling is the single biggest hay fire risk factor. Since 2000, there have been over 900 livestock and poultry barn fires in Minnesota, resulting in over $26 million in damages (Minnesota Fire Incident Reporting System). Although not specifically tracked by MFIRS, some of these fires have been caused by spontaneous combustion of hay that was baled too wet.

Although most hay fires happen within two to six weeks after baling, they can occur in hay several years old if hay is rewetted or mixed with newly baled hay. Hay baled at less than 15 percent moisture has a minimal risk of fire. As moisture content increases, the risk of dry matter losses and fire increase.

Here are some additional steps to reduce chances of hay fires:

• If you’re buying hay out of the field, know what the moisture content is.
• Storing hay before purchase reduces the chance of hay fires for buyers.
• Hay should be stacked to encourage air circulation; and should be stored where it’s protected from rain.
• Do not mix newly baled hay with older hay.

You can use forage moisture testers to measure moisture of hay in the field. However, accuracy varies so several samples should be taken.

Propionic acid can be used to help prevent molding in hay between 17 and 25 percent moisture, depending on the bale size.

If possible, store hay in a separate building from where livestock are housed. This will not prevent hay fires, but will protect animals in the event of a fire.

More information is available on the Extension forage website at http://www.extension.umn.edu/forages.

(Krishona Martinson is an Extension crops educator with University of Minnesota Extension.)