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Preventing Hay Fires with a Thermometer

SPRINGFIELD, Mo. — Farmers can prevent hay fires by monitoring hay temperature after baling according to Tim Schnakenberg, agronomy specialist with University of Missouri Extension.

Q: Many hay barns in the Ozarks have been lost to hay fires over the years. What can farmers do to prevent this from happening?

A: A wet spring has made hay harvest challenging. As a result, there has been some higher moisture hay baled which has led to concerns about spontaneous combustion. “If hay is harvested in the upper 20 percent moisture range or higher, it is possible that within six weeks of baling a fire will occur internally in hay bales. This can lead to hay fires and barns lost, especially if hay is packed away in barns. Keeping the moisture down to 16-22 percent when baling is the best thing to do,” said Schnakenberg.

Q: How does a farmer know if there is a problem?

A: Moisture meters are available, and many farmers own them. MU Extension specialists suggest that for farmers that harvest a lot of hay, a long thermometer is probably a better tool for monitoring wet bales. “The core temperature of a bale can say a lot about what’s going on inside and if there is a concern. Probe several bales because some bales may be dryer than others. Hay normally goes through a heat during curing and most of the time will peak out in temperature about 5-7 days from harvest,” said Schnakenberg.

Q: How hot does hay need to get to have a problem?

A: If the temperature goes between 130 and 150 degrees Fahrenheit, close monitoring is important. If over 150 degrees, it may continue to climb, and it needs to come out of the barn to improve air circulation. By 175, fire is a strong possibility. “If the temperature gets much over 175, moving it out of the barn can stimulate a fire when the air is introduced to the pile, so the fire department needs to be on standby,” said Schnakenberg.

Q: Where can you get long thermometers and more information?

A: All of the MU Extension offices in southwest Missouri keep thermometers on hand to loan out to producers for this purpose. These thermometers are available for purchase online, at farm suppliers, or at compost supply outlets.

For more information, contact any of these MU Extension specialists in southwest Missouri: Tim Schnakenberg in Stone County, (417) 357-6812; Jill Scheidt in Barton County, (417) 682-3579, Sarah Kenyon in Howell County, (417) 256-2391, or Elizabeth Picking in Howell County, (417) 256-2391.