MU Expert shares tips to reduce hay fires this season

Wednesday, June 7, 2017

Most common cause: excess moisture

Fires that damage or destroy hay and barns cost farmers thousands of dollars each year, resulting in lost revenue and the need for building and feed replacement. Proper harvesting and storage practices will reduce the possibility of hay fires and reduce the associated costs, according to Bob Schultheis, a natural resource engineering specialist with University of Missouri Extension.

"You can reduce fire and mold risk by baling small square bales at 18 to 22 percent moisture content," said Schultheis.

Because large round bales contain three times more hay per square foot of surface area, it takes longer for the bales to give up their moisture, so they need to be baled dryer at 14 to 18 percent moisture content.

"Higher moisture levels increase microbial activity and result in loss of dry matter and usable protein, which can reduce the feeding value of the hay by as much as one-third," Schultheis said.

Hay fires usually occur within six weeks of baling, because the most common cause is excessive moisture. Heating in hay bales will occur to some extent in all forages over 15 percent moisture content, with a peak in temperature four to seven days after baling, according to Schultheis.

"It takes 15 to 60 days for the hay temperature to decline to non-damaging levels, depending on outdoor humidity, the density of the bales and amount of rain the bales soak up. The longer it takes for the hay temperature to decline, the more damage is done to the hay," said Schultheis.

Safe storage temperature for hay is 120 degrees Fahrenheit or less. New hay that is stacked in the field or placed in a barn should be checked at least twice a day for abnormal heating.

"If storing hay inside, be sure the barn roof and plumbing do not leak and that surface water cannot run into the barn," Schultheis said. "If the hay temperature reaches 130 degrees, move the hay to allow increased air circulation and cooling."

If the temperature climbs above 150 to 175 degrees, call the fire department and be prepared to inject water to cool hot spots before moving the hay. Don't open the barn door if the hay is smoking. The added oxygen can cause the hay to burst into flame.

Hay temperature can be easily checked using a composting thermometer. Lacking a thermometer, a probe can also be built using a 3/8-inch diameter pipe with a pointed tip screwed to the end and holes drilled in it. A thermometer can then be inserted into the pipe and retrieved and read after 10 to 15 minutes.