A metal rod – and diligence in using it – could save hay growers from disastrous hay fires, suggests David Torsell, Jr., Ohio State University emergency management and agricultural rescue program manager.

Hay thermometers are commercially available, but a metal rod driven into a haystack is also an effective way to monitor heat.

“Leave it in there awhile,” he explains. “When you pull it out, if it’s too hot to handle, then they have a problem.” Repeated monitorings at random places within each hay lot are recommended.

When farmers detect high heat in hay, the temptation is to immediately remove the bales from the barn. But an internal bale temperature of more than 150º is dangerous and, at 170º, hay can spontaneously combust. Moving bales will introduce air to smoldering hay and fire can spread quickly.

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First remove animals from barns, then call the local fire department out to your farm in case the hay ignites, says Torsell, who has 37 years of fire-fighting experience under his belt. Only then should hay be removed and keep unaffected bales separate from the hot material.

“I’ve seen it done right, and it prevents a barn from burning down,” he says. “It takes teamwork. It’s something that needs to be planned for.”

One step toward preventing a fire: Store bales in the right kind of building, he says. Steel structures trap and reflect heat, while wooden barns with plenty of ventilation often help cool down stored hay.

Some safety experts believe loosely stacking stored hay can help reduce fire risk. But farmers still need to check temperatures, Torsell warns. If the hay has a moisture content of more than 20%, bacterial growth within the bales creates heat – and the threat of spontaneous combustion.

“It is hard to imagine how that happens when moisture is involved, but it’s a fact of nature,” Torsell notes.

This year, stored hay is especially susceptible, he says. “Some of this late hay that people got has had two or three rains on it. I’m sure they are going to have to watch the moisture content.”

Monitor hay temperatures continuously, because spontaneous combustion can occur weeks after bales are harvested and stored, he says.

According to research by the National Fire Protection Association, the top causes of barn fires include heating equipment, electrical and lighting equipment, arson and spontaneous combustion.