-Submitted photo courtesy of ISU Extension
This combine suffered extensive damage after a 2021 fire in Louisa County, in this photo provided by ISU Extension.

When field conditions are dry at harvest time, the risk of a combine fire escalates. All it takes is a spark from an engine, an overheated bearing on a combine or a hot exhaust manifold where some dirt and dry plant material has accumulated.

That dry plant residue, dusty conditions, low humidity levels and strong winds are a recipe for combine and field fires. During harvest periods with increased fire potential, fires cause millions of dollars in property damage in Iowa, including loss of machinery, crops and time.

Farm safety specialists encourage producers to carry two ABC-rated fire extinguishers with them — a 10-pound one in the cab and a 20-pound extinguisher anchored on the combine toward the ground level. A few extra extinguishers stashed in other pieces of machinery or trucks is a wise idea, too.

It’s also important to know how to use them and to know your exact location in the event of an emergency.

“If you rent property or own property not located at the family farm, write down the 911 number to that property and keep it in every vehicle that might go to the property. As 911 centers have become county or regional, you can’t say, ‘I am at the old Joe Smith farm.’ Having the 911 number will cut down the time it takes to get a response in an emergency,” said Dan Neenan, director of the National Education Center for Agricultural Safety.

Dennis Friest, Iowa Corn Growers Association president, said he was in a combine that was only 2 or 3 years old when he suddenly smelled smoke.

“I looked around everywhere and finally found a little wire that had shorted out. It was smoldering,” said Friest. “It didn’t burn up the combine, but I ended up replacing this one piece of wiring that ran from the cab to the engine. It was $8,000 for just the wire harness.”

While producers cannot eliminate fire risks such as the heat produced by the engine, hydraulics and other systems, growers can remove the fuel source by keeping a combine and other equipment clean.

It’s important to keep the engine compartment of the combine cleaned out to help reduce the risk of fire. Something as simple as a leaf blower will help blast the debris and flammable material caught up in the combine. Carrying a spade or shovel to help toss dirt on a fire is helpful, too.

“Us farmers usually have air blowers and have just made it a practice to blow off the combine at the end of the day. It’s important to keep it as clean and clear of debris as possible,” Friest said.

“If we don’t, that can create severe problems. Every year there are combine fires and if the field also catches on fire, it can travel across quite a few acres.”

Friest also recommended regularly walking around a combine and checking for a burning smell.

Meaghan Anderson, Iowa State University Extension field agronomist, said most of central Iowa has received more rainfall this growing season than most other parts of the state, but quite a few counties are still drier than usual.

“It is difficult to say whether these dry conditions will persist and cause issues at harvest at this point. The weather forecast appears to be leaning toward a chance of wetter conditions in the coming months, so I hope we can have a low chance of fire issues,” Anderson said. “The risk is always present though, so if the weather stays dry and especially if we have high winds, there will be a risk of field fires and combine fires.”

Joshua Michel, field agronomist with Iowa State University Extension, offered the following fire prevention tips for pre-harvest and also on an ongoing basis:

• Keep the machine clean, particularly around the engine and engine compartment. Use a high pressure washer or compressed air to remove caked-on oil, grease and crop residue.

• Frequently check air filters, ensuring that they stay clean; either by blowing them out or replacing them. This will help the engine run cooler and more efficiently.

• Check coolant and oil levels daily. Pay close attention to engine and hydrostatic pump parts as well.

• Check the pressurized oil supply line to the turbocharger for wear areas that rub and may start an oil leak.

• At the end of each day, blow leaves, chaff and plant material from the engine area with either compressed air or a portable leaf blower. Waiting until the next morning to do this may be more difficult because of the dew.

• Remove plant materials wrapped on or near any bearings, belts, chains or other moving parts.

• Examine the exhaust or any hot bearing surfaces. Repair leaking fuel or oil hoses, fittings or metal lines immediately.

• Inspect and clean ledges or recessed areas near fuel tanks and lines.

• Prior to refueling, turn the combine off and wait 15 minutes to reduce the risk of a spill volatilizing and igniting.

• Research from South Dakota State University suggests that if growers have dry conditions and start experiencing wind speeds close to 30 mph and above, fires may be inevitable. During these periods, producers should consider delaying harvest until evening hours when winds decrease or wait for precipitation. Higher humidity levels may also reduce the potential for field fires to spread.

Michel noted that if a fire breaks out, a grower should turn off the engine instantly, get away from the combine and call 911. If safe, grab a fire extinguisher and try to fight from the “black,” which is the area already burned.

“Attacking a fire from areas with combustibles (e.g. dry corn stalks) is much riskier. Always stay upwind of a fire to minimize the risk of exposure from smoke, heat and possible flames,” Michel said. “A fire can double in size in less than a minute. Burning embers blown downwind can easily spread a fire well beyond the control of your fire extinguishers in just seconds. So be aware of possible additional fires.”

Also be sure to invert the fire extinguisher once or twice during the season to ensure that machine vibrations don’t compact the powder inside.