Friday, October 30, 2015

Dry Weather Makes Field Fires a Safety Concern for Farmers and Neighbors

This season, farmers are at a high risk of having a field fire. In less than a week we have had at least two field fires in the county and a few in our neighboring counties.

What is fueling these fires you may ask? We had a tremendous amount of rain this past growing season which in turn produced a corn crop with a lot of fodder. We also have had less than a half inch of rain for most of the county since corn harvest began. Add in high winds, a discarded cigarette or a blowing ember from a trash fire and you have the opportunity for a major field fire.

These field fires can grow out of control in a matter of minutes. Adjacent homes, buildings and standing crops all are at risk

Additionally the conditions present during harvest season include dry plant material and grain dust that are highly combustible. Hot equipment or engine sparks are great ignition sources. It is not uncommon for exhaust pipes or catalytic converters to exceed 1,000°F. Add a little wind and there is a perfect opportunity for a field fire.

Fighting a field fire can be quite the challenge and should be directed by the fire department in charge. You may be of assistance if you have a tillage tool ready to go to “plow” a barrier. When plowing the barrier you do not want to attempt to till the ground at the fire. You would want to keep a safe distance between the fire and your tractor. Directly tilling the ground at the fire may result in severe damage to the tractor and a risk to the operator.

Being prepared to handle field fires is important for all workers and transport drivers. Combines, tractors, grain trucks, and pick-ups should all be equipped with a trustworthy fire extinguisher as the first lines of defense. Combines should carry an ABC 10-pound fire extinguisher in the cab and a larger 20-pound unit at the ground level. Tractors and trucks are recommended to have a 5-pound minimum extinguisher available. These extinguishers should be in EACH vehicle in the field. Nothing is worse than watching the combine go up in flames while you're running to the end of the field to retrieve the fire extinguisher on the grain cart. Having an extinguisher on each piece of equipment ensures you will be ready to react on the first signs of smoke.

Don't get caught with a false sense of security.

If you follow the recommendations and own enough fire extinguishers, then you must also follow the maintenance recommendations. Check the pressure gages periodically, making sure the needle remains in the "charged" zone. If a unit has been partially discharged, it must be fully recharged before using it again. Even a slight discharge can create a gap in the internal seal of the extinguisher valve, causing the pressure to leak out. The pressure needle may linger in the charged zone; however there may not be adequate pressure to expel the contents.

Extinguishers could use a little shake a few times a year. By inverting the extinguisher and shaking it several times each season makes sure the powder doesn’t get lodged at the bottom of the unit. Equipment vibrations are notorious for compacting the reactive ingredients of fire extinguishers; making them worthless when they are needed.

Extinguishers should also be inspected periodically by a fire professional. Fire service companies can be found in community directories. Your local fire department or insurance company can also point you in the right direction for service companies. Some extinguishers are not designed to be refilled, or are too old to be refilled. These units should be replaced when they expire. Having these old extinguishers around does no good when the time comes to pull the pin.

Follow other fire prevention practices.

It is also important to keep machinery in good repair. Apply grease to bearings and oil chains regularly to reduce friction. It is recommended to perform maintenance checks at the end of the day, rather than at the beginning, to detect any hot smoldering areas that may break out into flames overnight.

Keep machinery clean and free from plant materials, especially around the wrap points. Wipe up any fuel or oil leaks to eliminate additional fuel sources; and do not leave oily rags on equipment or in the cab.

Use an air compressor or leaf blower to remove crop residue, and a pressure washer to remove built up oil or caked-on grease.

Take time to cool down the equipment each night, and check for any hot spots. These steps can make a difference to save equipment, facilities, commodities, and lives.

Being prepared to handle field fires is important for all workers. Having machinery equipped with a trustworthy fire extinguisher is one of the first lines of defense.

Nutrient Losses from Burning of Corn Residues

With dry weather and corn stubble sitting in the field, residue can be quickly turned to ashes due to accidental fires. A question frequently asked afterward is how much nitrogen (N) just went up in smoke? N is volatilized and lost when plant material burns. Phosphorus and K remain and return to the ground with ash. However, P and K could be lost if ash is blown away from the field during or after the fire. Fire damage in a field is usually variable in scale. Not all material is completely turned to ash, and rarely is the entire field burned (from one end to another). Understanding what was burned and how much area was affected has an impact on the total amount of N lost. The amount of N contained in corn residue has been well documented from the late 60’s and clearly delineated by John Sawyer at Iowa State (

To estimate how much N was lost, the grain yield level for the previous year must be considered. The harvest index (in corn, the ratio of grain weight to total plant dry weight) is another piece of information that must be known (if unknown – assume 0.5). Providing a relatively accurate measure of the area affected is obviously important. Additionally, recognizing the residue remaining and adjusting the material burned can provide a more quantitative measure of the actual damage (if this is unknown - assume 100%).

The table below provides a simple estimate of N lost based on the previous year’s corn yield (assuming a harvest index of 0.5 and yield adjusted to 15.5% moisture). (Remember: the N contained within the corn residue would not have been released and made plant available for next season’s crop.)

Yield  (bu/A)
 N  lost  (lb/A)

Along with the loss of N, carbon contained in the plant material is lost as well. It would have been incorporated into the soil organic fraction. This too has value. While there is no specific dollar amount tied directly to a loss of organic matter, an Iowa State University article recommends that one dollar per acre should be claimed. Unfortunately, the economic impact associated with the loss of residue cannot be fully realized until later, especially in fields with high erosion potential.

Be fire smart, and safe harvesting.

For more detailed information, visit the Darke County OSU Extension web site at, the OSU Extension Darke County Facebook page or contact Sam Custer, at 937.548.5215.

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