Hay making is in full swing in Tennessee, and in the rush some farmers will bale hay before it cures properly, ending up with spoiled hay or, in some instances, fires.
Hay fires typically result from bacterial heating that takes place in hay baled at an excessive moisture content. Some heating will occur in any hay, but usually peaks at about 140° after a few days. With enough moisture and oxygen, bacteria flourish and continue heating until hot enough to ignite the hay.
Round bales are more susceptible to spoilage and burning than conventional square bales. Cores of round bales arc insulated by two feet or more of hay and are not able to cool and dry. However, fewer barns are lost to round bales because most round bales are stored outside.
Check hay moisture content prior to baling to prevent spoilage and fires. Bale at 15-18 percent moisture for round bales and 20-25 percent moisture for conventional square bales. Round bales can be formed at 20-25 percent moisture with proper use of proprionic acid as a preservative.
Check the moisture content and temperature of bales again before storage to make sure they are safe.
A hay moisture and temperature meter is essential, because you can't accurately judge moisture content by sight and touch. The meter may seem expensive, but it will help you produce better hay and protect your investments (production costs and structures).
You may need to leave round bales in the field up to two weeks or more before storing to allow the heating process to finish. Continue monitoring the temperature in the storage area regularly until you are sure there is no danger of fire.
Take action immediately if you find temperatures above 160°. Move the hay to a safe location and allow air circulation for cooling and drying.
Call the fire department if the stored hay exceeds 180°, especially if there is smoke or the smell of burned hay. Do not move this hay until the fire department is at the scene and has a charged hose ready to knock down any blazes. As soon as you move the hay, any smoldering hay could immediately blaze up. A garden hose will not be sufficient to control the fire.
The most effective method of controlling a hay fire is to inject water directly into the hot spot to cool and wet it before exposing it to the air. This can bc done with a simple probe that can also be used for checking temperatures to locate hot spots. Wetting agents are not needed and they contaminate the hay, making wetted hay unusable.
more information on hay fire prevention and control, get a
copy of publication 1306 from your county Extension office.
Your Extension agent can also provide other information on
producing and storing high quality hay for maximum nutritional
This news release was distributed by the University of Tennessee Agricultural Extension Service, Knoxville, Tennessee 37901. Publication date: May 1993.
Timothy G. Prather, Agricultural Safety Specialist, Agricultural Engineering Department, University of Tennessee Agricultural Extension Service, Knoxville, Tennessee 37901.
Disclaimer and Reproduction Information: Information in NASD does not represent NIOSH policy. Information included in NASD appears by permission of the author and/or copyright holder. More