By Jeff Burbrink
Ag & Natural Resources Extension Educator, Purdue Extension LaGrange
LAGRANGE — There are few things more dramatic than a combine on fire. The smoke billows up from the machine as crop residue, belts, plastic parts, fuel, and other flammable materials ignite, often with spot fires popping up in the surrounding crop residue. At night, the glow can be seen for miles.
Our family lost a John Deere 6600 in the early 1980s in a cornfield just south of Camp Atterbury in southern Indiana. I remember Mom, the driver of the combine, describing how quickly it all happened. In a matter of minutes, the machine and parts of the surrounding field were in flames.
Does it seem there are more combine fires in modern times than 40 or 50 years ago? It is likely the number of fires is about the same. However, modern combines are built with more plastic, fiberglass, and other lightweight, combustible materials, with more electronic components, making modern machines more likely to have spectacular events.
Every fire has three elements: an ignition source, fuel, and oxygen. Failing bearings, electrical shorts, even rocks tumbling about the interior can ignite crop residue, leaking fuel or lubricants that serve as the fuel. Some components of the combine’s electrical systems are also at higher risk of overheating, particularly starter motors and heating/ cooling systems that draw a heavy electrical load. Fuses that blow regularly should be considered an important warning sign that a circuit is overheating somewhere.
Cleaning crop residue and dust routinely from the harvester can reduce the ignition source and may also reduce weed seeds that could be moved from one field to the next.
Not all combine fires occur while operating in the field. It is not unusual for smoldering residues to reach critical temperatures overnight, well after the field work is done for the day. Daily inspections can reduce the risk of pockets where dust and residue build up.
Seconds matter when a fire starts. The priority is to prevent human injury, so if the fire is near the cab, it is best to get out as soon as you can. Cabs are often equipped with fire extinguishers, but if the flames are nearby, consider cutting your losses and getting to safety. Some combines are now equipped with additional fire extinguishers, mounted in locations within reach at ground level. Most are standard 10-pound ABC extinguishers, but with more combustible parts on modern harvesters, 20-pound units may be advisable. The extinguishers should be checked and inspected annually for leaks and integrity.
What to do if you discover smoldering residue, but not a full-blown fire? First, do not immediately begin to pull the crop residue away. That may expose the hot embers to oxygen and escalate the situation, plus embers dropping to the ground may ignite the field itself. Call 911 for help when you are out of harm’s way. Secure the fire extinguisher and aim at the base of the flames should they break out.