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TIMELY TOPICS
Fires can be caused by the spontaneous combustion of hay. The risk of this happening is greatest within the first six weeks after baling. T he past week has seen a great deal of first cutting hay mowed in Rockbridge County and farmers should be on their guard for hay that may be susceptible to combustion.
Plant respiration can be defined as the burning of plant sugars to produce energy for the plant. This process releases a small amount of heat and it continues in the plant even after it is cut. Once the moisture concentration in the plant drops below 20%, plant cell respiration will slow dramatically and will eventually cease. If bale moisture levels are too high (greater than 20 percent), the heat and moisture will provide a suitable environment for the growth and multiplication of bacteria species that can raise the interior bale temperature to 170°F and hay can potentially ignite. Even hay that is baled at the proper moisture concentration can become a potential fire hazard if it becomes wet during storage especially if this occurs soon after harvest. So if hay was temporarily stored outside and was rained on, steps should be taken to insure it has dried before it is tightly stacked in a barn.
Hay moisture concentration has a major effect on the microbial activity that can lead to hay fires. Therefore, hay should be cured to the proper moisture concentration prior to baling. Virginia Cooperative Extension recommends baling at a moisture concentration of 20% or less for small rectangular bales. Large rectangular or round bales should be baled at 18% moisture or less. Information for this article is drawn from Virginia Cooperative Extension Publication 442-105 “Hay Fire Prevention and Control” and it details strategies to prevent hay fires and how to safely monitor temperature in hay stacks. Additional useful information can be drawn from VCE publication 442-106 “Determining Forage Moisture Concentration” and VCE publication 442-454 “Management Tips for Round Bale Hay Harvesting, Moving, and Storage”.
These publications are available on the internet or printed copies are available at no cost at the Rockbridge Extension Office. Feel free to call the Extension Office at (540) 463-4734 or send email to [email protected] for more information.
