Quality Hay & Straw for Sale Year-Round

June 11, 2019 08:00 AM
By Michaela King

This spring has not been a kind one to farmers. If current weather patterns continue, this sets up a scenario where hay harvest moisture is pushed to the limit or cut hay gets rained on. High-moisture hay (usually bales over 30% moisture) is at risk for spontaneous combustion for up to three weeks after harvest. Mesophilic bacteria inside the bale produce and release heat and cause temperatures to reach 130°F to 140°F.

At this point, the best scenario is the bacteria die and the bale begins to cool. However, if bacteria take over, temperatures can rise to over 175°F and fire pockets are likely to form.

The best way to reduce the risk of fire is to bale under the right conditions. The ideal weather is a slight wind with humidity levels of 50 percent or less. This year, days with these conditions have been far and few between.

Proper storage reduces the risk of hay fires. Factors such as volume of bales and density of the stack and airflow between bales play a big role in lowering stored hay temperatures. Experts say bales with a lower density that aren’t stacked too deep and have good ventilation and airflow are at a lower risk of overheating.

Checking hay

If you are concerned hay may be baled too wet, monitor internal bale temperatures twice daily for six weeks after baling. Check internal temperatures at the center of the stack or around 8 feet down in larger stacks.

A method for determining fire risk is sticking a 3/8-inch pipe into the stack twice a day. If the pipe is too hot to hold when removed, hay is at risk for fire.

Different temperatures … different risk…

According to experts, hay temperatures around 120°F to 130°F don’t cause fires, but they promote mold growth and lower the amount of protein available in the hay. Continued mold growth can raise temperatures to dangerous temperatures and once hay reaches 160°F to 170°F, alert the fire department immediately. At those temperatures, additional chemical reactions occur, and the temperatures rise even higher. In a short period after this begins, spontaneous combustion normally occurs. (NOTE THE WORDS USED HERE).