Newark, Ohio (AP) -- Fire officials say a central Ohio County has seen two recent barn fires caused by spontaneous combustion.
Investigators say both barns in Licking County were destroyed after hay suddenly burst into flames.
Ohio State University farming expert Marc Sulc says spontaneous combustion can happen when microbes grow and generate heat within moist hay.
He says microbes thrive in warm summer weather.
The first fire occurred July 7 and caused an estimated $80,000 damage.
The other barn burned to the ground on Monday; damage was put at $250,000, including the losses of a tractor and feed mixer.
The farm owners say they had applied a preservative to their hay to prevent spontaneous combustion.
However, Sulc says those preservatives can wear off.
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