Almost every year someone loses a barn from fire caused by damp hay that spontaneously combusts according to Eldon Cole, a livestock specialist with University of Missouri Extension.
"So far no reports of that have happened in 2015 but considerable hay has been put up with the dampness potential for fire," said Cole.
Fire prevention starts at baling according to Cole. It is recommended that small, rectangular bales be right at 20 percent moisture or lower. Large round bales should be in the 18 percentage range or less, especially if they are to be stored in a barn.
"It is usually wise to leave large rounds outside a barn for a couple of weeks. During this time, you can monitor the temperature. The bale temperature may go up to the 120-degree range then begin dropping to a safe level. Up to this temperature, the hay quality has not been damaged to any extent. However, there may be some mold develop," said Cole.
The greatest concern for fire risk and quality loss comes as the internal bale temperature rises to 130 to 150 degrees. The temperature can increase over a period, so Cole regularly recommends checking the temperature every four to six hours.
Cole recently received a call from a farmer who had baled some large round bales at around the 20 percentage moisture level. Rain was forecast, so he felt it best to wrap it up.
"This was on a Friday. He put the hay in a barn and on Monday he checked, and some of the bales were in the 150-160-degree range. We discussed when and if he should remove them and decided it was better to be safe than sorry," said Cole.
The bales were removed with no incident.
"When I checked back with him the following day, and some bales now were up to 182 degrees but were not smoking. He was happy the barn was saved," said Cole.
The use of moisture testers and thermometers can improve haymaking and maybe even save your barn, according to Cole.
Source: University of Missouri Extension