Dry spring field conditions cause concern for field fires

April 2, 2021 1:30 PM
Blog Post

The recent dry conditions across the state, carried through from the 2020 growing season, has created an environment in which field fires are of concern this spring if current conditions continue to persist.  Strong winds can increase problems by acting as a catalyst, drying crop residue, enhancing the chances for a fire to be started, and increasing the scope of the fire if it’s already been ignited. As we begin field operations this spring, it’s important to remember practices that can be used to help prevent fires from occurring, as well as considerations for safety if a fire spreads to your fields, and the potential for nutrient losses in the advent of a field fire.

In all situations, remember that personal safety is more important than property loss.

Fire Prevention Tips

  • Keep machinery clean, particularly around the engine and engine compartment. Use a high pressure washer or compressed air to remove caked-on oil, grease, dirt/dust and crop residue. Using a leaf blower or compressed air to are good ways to complete this in the field. Doing this at night is often better than in the morning when dew or overnight rain can make dirt and residue harder to remove.
  • Fires may start from plant materials that have smoldered unnoticed for 15-30 minutes or more. The ignition source for field fires may have been the earlier passing of a piece of equipment. Flames aren’t apparent until additional oxygen is supplied, perhaps by a gust of wind. Consideration should be taken to discuss a plan for emergency tillage of a fire break should that option become advisable.
  • Check coolant and oil levels daily.
  • Check the pressurized oil supply line to the turbocharger for wear areas that rub and may start an oil leak.
  • Remove plant materials or other debris (baling twine, net wrap, fencing wire) wrapped on or near bearings, belts, or other moving parts.
  • Examine exhaust or 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 fueling, shut the engine off and wait 15 minutes to reduce the risk of a spill volatilizing and igniting.
  • Research from South Dakota State University suggests that if we have dry conditions and start experiencing wind speeds close to the thirty mile per hour range and above, it is likely fires will be inevitable, and producers should consider delaying field operations until evening hours when winds decrease or wait for precipitation.
  • Two ABC-type fire extinguishers are recommended: a smaller 10-pound unit in the cab and a larger 20-pound extinguisher at the ground level attached to the equipment. It can also be beneficial to keep a pressurized water extinguisher (class A) on equipment. These can help extinguish fires, but also cool hot surfaces and serve as a water source to clean hands or rinse off after some sort of fuel or chemical spill.
  • Invert and shake the extinguishers once or twice a season to ensure machine vibrations don’t compact the powder inside and ensure they are properly charged and not expired. Class A water extinguishers need to be kept in a heated area during winter months as they will freeze.
  • Have accessibility to a shovel to throw dirt onto a fire or move crop residues away from a fire.
  • Be mindful of non-ag equipment vehicles that may be in your fields. UTVs or passenger vehicles often sit closer to the ground and can be more prone to causing field fires. Residue buildup in UTVs engine compartment are an often overlooked source of fire ignition.
  • Newer diesel engines often go through a regeneration process to burn soot from their DPF (diesel particulate filter). During this process, exhaust temperatures can reach extremely high temperatures often in excess of 1,000 degrees Fahrenheit. Ensuring equipment is clean and not parked or working in an area where the exhaust is exiting the vehicle near a combustible material helps ensure equipment in a regeneration state does not ignite a fire.

Call 911 First

  • If a fire has broken out, call 911 first, and then attack with fire extinguishers if it is safe to do so.
  • Having the 911 address of the field (before needing to use it in a call) can help save time and expedite the response from emergency responders.
  • Always stay upwind of a fire to minimize the risk of exposure from smoke, heat, and possible flames (due to wind gusts).
  • Try to fight from the “black," the area already burned; fire attack from areas with combustibles (like crop residue) is much riskier.

Create a Firebreak Using Tillage

  • Making a tillage pass along the outside edge of a field (especially a corn field that can provide ample fuel for a fire due to high amounts of residue), has been a proven preemptive strategy to help prevent fires from spreading into a field.
  • If safe to do so, making a firebreak with a tillage pass, can help stop an active, out of control fire from spreading. The goal is to create an area that won’t fuel the fire, so the fire will eventually burn itself out.
  • A good rule of thumb is to create a fire break that is 2-3 times as wide as the nearest surface vegetation or plant residue is in height (example; 3 foot tall brome grass along a field edge = 6-9 foot tillage width). Keep in mind that depending on wind speed and gusts, the radiant heat and embers from a fire can “reach out” sometimes twice as far as it normally would be able to. Consequently, a fire break may need to be considerably wide (up to 30 plus feet) to help ensure proper fire containment.

Nutrient Loss Considerations

Nutrients like potassium and phosphorus typically remain in the ash, but most nitrogen remaining in residue will be lost in a fire. In 2017, John Sawyer, Soil Fertility and Nutrient Management Extension Specialist, wrote a couple of ICM articles titled: “Estimating losses when cornstalk fields are accidentally burnt”  and “Dry fall conditions can lead to field fires” that address this topic and are still relevant for this spring.


Terry Basol Field Agronomist in NC Iowa

Terry Basol is an agronomist in north central Iowa and field specialist for Iowa State University Extension and Outreach.