Warm, dry conditions increase risk of combine fires

North Dakota State University Extension

Row crop harvest is in full swing across North Dakota, with many crops near harvest completion. Weather conditions have been warm and dry, allowing producers to harvest crops without the pressure to get the grains harvested before winter arrives. However, dry and warm conditions increase the risk of combine fires, especially when harvesting sunflowers.

In 2022, North Dakota saw a huge increase in planted sunflower acres, with the National Agricultural Statistics Service (NASS) stating that oil sunflower acreage increased 48%, while confectionary sunflower acreage increased 62%.

Warm, dry harvest conditions in combination with high winds increase the risk of combine fires.

“The increase in planted sunflower acres and warm, dry weather conditions means an increased risk for combine fires,” says Angie Johnson, NDSU Extension farm and ranch safety coordinator. “Mix warm, dry harvest conditions with a high wind speed, and you have a recipe for harvest fires.”

In mid-October, the North Dakota Agricultural Weather Network reported wind speeds over 34 miles per hour, which does not include the high wind gusts that were also occurring during that timeframe.

“The high wind speeds we are experiencing and the large amount of extremely dry plant material in our fields and grasslands creates perfect conditions for fire when provided with an ignition source, such as the hot exhaust from the combine’s turbocharger or exhaust manifold, or even from an electrical malfunction in a plastic wiring harness on the combine,” Johnson says.

Combine fires can occur at any time with the right conditions. Sunflowers, however, pose a greater risk because of the large volume of dust and particulate they produce while being harvested, says Johnson. The white portion inside the stalk, known as the pith, breaks down into very small, tiny particulate pieces with large surface areas that easily get sucked into the fan that is pulling air through the machine’s radiator to cool down the engine. That pith dust and particulate easily sticks to engine and exhaust components and can ignite when it comes into contact with the turbocharger and exhaust system of the combine.

“One of my biggest concerns with the large increase in sunflower acres is that we may have new sunflower producers harvesting those fields, or producers who have not raised sunflowers for a number of years that may not be prepared for the increased fire risk that accompanies sunflower harvest,” says Johnson. “Believe it or not, there was a time when producers made the decision to quit raising sunflowers because of the constant fire risk and complete combine losses that took place because of combine fires due to sunflowers. Fortunately, we have improved prevention tools and strategies to help mitigate and reduce the risk of combine fires during sunflower harvest.”

Johnson shares the following tips for reducing the risk of combine fires while harvesting sunflowers:

  • Pre-operational checks. Take time to walk around the combine before the start of each day during harvest season. Use an air compressor or leaf blower every day when the machine is off and cooled down, to remove dirt, dust, chaff and other plant reside that has accumulated. Always wear hearing protection, eye protection and respiratory protection, such as an N95 mask, when using an air compressor or leaf blower to remove plant dust and reside. While blowing off residue, look in high-risk areas, such as the engine and engine compartments, hydraulic pumps and pump drives, gear boxes, batteries, and cables. When cleaning, take time to look for any issues that require repair, such as leaking hydraulic hoses that can be a perfect place for chaff to stick and build up, creating an easy fuel source for a fire.
  • Take time to service the machine daily, based on the combine’s operator manual. Grease and lubricate bearings and chains and continue to look for areas that have excessive wear or damage.
  • Watch for wiring issues. Today’s combines are controlled by many sensors and electrical components that are extremely complex. Take time to glance through wiring systems to see where wires appear to be unrestrained or if wires appear to be damaged from rubbing or making contact with moving parts.
  • Use an infrared thermometer. Hot bearings are a combustion source. To check the bearings, warm up the combine before taking it to the field and use an infrared thermometer to determine the operating temperature of your combine’s bearings. Safely open the combine’s shields, including the header, and from a safe distance, point the infrared thermometer at a bearing to read the measured temperature. If the thermometer measures a bearing’s temperature that is much higher than others, it is time to replace that bearing, as it may be worn or damaged. Infrared thermometers are inexpensive (less than $50) and can be found at many hardware and farm stores.
  • Install an air intake kit. An air intake kit allows clean air found above the combine’s “dust cloud” to enter the combine’s air intake screen, instead of taking in the dusty, dirt-filled air produced from harvesting the crop. Take the time to consider an option that will work best for you and your combine.
  • Avoid combining during fire danger conditions. Believe it or not, harvest conditions can be too good, meaning it can be too warm and dry to combine your crop. Relative humidity values are low in the fall, increasing the risk of fire, especially in the late afternoon hours. Keep an eye on outdoor air temperature, relative humidity and wind speeds. As hard as it is to shut down for the day when conditions are favorable for harvesting, shutting down when temperatures are hot, dry and windy could prevent you from losing your combine to a fire. Be aware and find out if your area is in a fire danger zone by visiting: https://ndresponse.gov/burn-ban-restrictions-fire-danger-maps. If you must continue combining, take extra precaution and clean your combine more frequently.
  • Carry two, fully charged fire extinguishers. Ideally, you should have two 20-pound, charged fire extinguishers on your combine. Have them ready and operational and review with workers how to use them when needed. Call 911 immediately to get your closest fire department on scene.
  • Create a soil perimeter. If you choose to harvest during high wind and temperature conditions, make a tillage pass around the perimeter of your field to prevent the possibility of a fire spreading to other areas on the landscape should a combine fire occur.

“Good machine maintenance, cleaning and monitoring can help reduce the incidence of combine fires during crop harvest,” says Johnson. “Make farm safety a priority on your farm this fall. Combines and crops are replaceable – you are not.”

For more information on crop harvest fire prevention, visit  www.ag.ndsu.edu/publications/crops/crop-harvest-fire-prevention-checklist.