NDSU Extension - Burleigh County


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Preventing Fires in Baled Hay

Murphy’s Law states that “Once you’ve baled your hay, it will rain!” This area is no stranger to inconvenient wet weather this growing season. And odd as it might seem, wet hay is more likely to lead to a spontaneous-combustion fire than dry hay. Understanding the causes of fires in stored hay and learning how to reduce fire hazards will protect your feed supply and could prevent the loss of time and money associated with a fire.


Moisture content is the main factor that causes hay to spontaneously combust. Hay fires are a danger at any time in stacked small bales when the hay’s moisture content is 20 percent or higher, and in stacked big square or round bales when the hay’s moisture content is more than 16 percent. Hay fires usually occur within six weeks of baling.


Other factors that contribute to the risk of hay fires include the volume of the bale stack, bale density, and ventilation or air flow around the stacked bales. Bales with a lower density that are stacked lower and have good air flow and ventilation have a lower risk of overheating. The best way to reduce the risk of a hay fire is to bale hay at a moisture content of 20% or less and stack them in a way where there is good air circulation.


Another way to reduce the risk of a hay fire is to ensure that stored hay remains dry. When storing hay inside, make sure the barn or storage area is weather tight and has proper drainage to prevent water from entering the barn. When storing hay outside, cover the hay with plastic or another type of waterproof material. If you are unable to cover the bales, arrange the bales so that air can circulate between them to promote drying. Baled hay


If you are concerned about the moisture content of your hay, monitor the internal bale temperature. If the internal temperature is 125 degrees F or less, there is no action needed. However, at 150 degrees F, hay is entering the danger zone. At this point, check the temperature twice daily and disassemble stacked hay bales to promote air circulation to cool the hay. At an internal temperature of 175 degrees F, hot spots or fire pockets are likely. Alert fire services to the possible hay fire incident immediately and stop all air movement around the hay.


For more information, contact:

Elizabeth Burdolski, Agriculture and Natural Resources

Burleigh County Extension (701) 221-6865

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