While it’s true everybody is happy for the rain, folks are scrambling in the Ozarks to get their hay put up. But rushing your hay to get it baled can bring other problems. In particular, the imminent threat of hay that is baled too wet catching fire.
High moisture content of hay can be a serious problem within days or weeks after it is stored according to Tim Schnakenberg, University of Missouri Extension agronomy specialist. Fires can occur in all types of hay whether it is loose or baled in square, small or large round bales or even stacked hay. Excessive moisture is the usual culprit in hay fires. Monitoring stored hay, especially during the first six weeks after it is baled, is important if hay is wetter than desired when baled.
Ideal hay making weather is when the humidity is less than 50 percent with some wind. Knowing that the moisture content will increase overnight especially if there is fog or dew is also important.
Using conditioning equipment that helps to crimp or abrade crop stems also helps to speed the drying process. Fluffing windrows with a hay rake or tedder can also speed the drying process.
“Hay should not be baled at moisture levels of higher than 18 to 20 percent. Hay that has high moisture levels will lose large amounts of dry matter and excessive heating and mold can occur. Spontaneous combustion is possible in some cases,” said Schnakenberg.
“Hay stacks can be probed with a long probe with a thermometer at the end. Some producers have made home-made probes using a long pipe no wider than three-fourths of an inch with a flattened end to probe between bales,” said Schnakenberg.
Holes are drilled in the pipe near the flattened end for heat to enter the pipe. A thermometer tied to a wire is dropped into the probe into the middle of the hay stack for monitoring. After 10 to 15 minutes, the thermometer can be retrieved to read the temperature. These “store bought” probes can usually be purchased at local garden centers as they are also used in composting.
“It’s not uncommon for the temperature to reach 130-140 degrees Fahrenheit. If it goes above 150 degrees, the temperature will most likely continue to climb. At this point you can move the hay to provide air circulation and cool it down,” said Schnakenberg.
Once the temperature reaches 175 degrees or above, fire is imminent and the fire department should be called.
“Moving the hay and exposing it to air at these temperatures may actually ignite a raging fire,” said Schnakenberg.
Temperatures of 200 degrees or above means fire is present and water must be injected into the stack before moving hay.
“If you see or smell smoke coming from the bales, avoid walking on top of the stack since a burned-out cavity may have formed that you could fall into. If you must get on top, walk on plywood or a ladder placed on the top, have a second person nearby and a tie onto a lifeline,” said Schnakenberg.
