Reducing Fire Hazards in Hay

The high temperatures of summer are a concern for livestock and forage producers. It is very important to remember what to do in order to avoid major damage to our production and stored forages.

Top Five Recommendations to Reduce Fire Hazards in Hay

1. Bale Density: Increased bale density will increase spontaneous heating potential due to the larger quantity of material in each hay bale and reduced heat dissipation. It is mainly affected by the baling machine, experience of the operator, and the hay type.
2. Bale Size: Large round or rectangular bales are at greater risk of maintaining higher temperatures than small rectangular bales. Though once tightly stacked, there is not much difference.
3. Moisture within bales: Wide swaths during harvest lead to more uniform drying, which can reduce the presence of wet or green spots in the windrows at baling.
4. Weather Conditions: Warm and humid weather plays a big role as it can contribute to lower heat dissipation from stored hay, making the hay extremely warm and at risk of fire. The majority of the heat in stored forages will depend on relative humidity, air movement, and temperature.
5. Storage Site: Even when stored, hay bales will lose moisture. It is highly recommended to have buildings well ventilated so the moisture can escape and doesn’t get trapped inside the hay bale. If you use outdoor storage, allow space between rows to encourage air movement.

Ironically, excessive moisture in stored forages is the primary cause of fire danger, which helps fuel biological decomposition that is the dangerous effect. The best recommendation that we can offer is to assure you harvest forages when weather conditions allow for the most drying possible and then when storing bales do so in a manner which allows for the most air flow around the bales so moisture is minimized.

Suggested Action Steps for Fire Hazard in Hay Bales

• When internal temperature of a bale reaches 150° F, monitor temperatures daily. 
• When internal temperature of a bale reaches 160° F, monitor temperatures every four hours. Separate bales if temperatures continue to rise.
• When internal temperature of a bale reaches 175° F, call fire department! Separate bales from buildings and other dry hay.
• When internal temperature of a bale reaches 185°F, call fire department! Do not move separate bales as air can start the fire!
• When internal temperature of a bale reaches 212° F, call fire department! Fire is imminent; Wet the hay; Do not move or separate bales as air can start the fire! 

Source: Karla Hernandez, South Dakota State University