Hay and forage fires are a significant risk on farms throughout Ontario so prevention strategies are important. Many regions of the province had a particularly dry May, increasing vulnerability to fire.
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Why it matters: Dry conditions have increased fire risk, particularly for forages. Fires can start when heat builds up in high-moisture material, causing spontaneous combustion.
Christine O’Reilly, the forage and grazing specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, said weather conditions led to more early hay production than is typical.
Though haying and other forage harvest in late May is common, it is often difficult to dry the material because the crop is less mature, the ground tends to be wetter and temperatures are not as hot.
“We had two weeks where it was dry and very low humidity, and a lot of the spring planting was done,” O’Reilly said. “People had time, and they went, ‘you know what, let’s make some hay.’ The weather forecast was perfect.
“A lot of hay went up at a time of year that we don’t normally get the drying window. And even though it was hot, the outside of the crop looked dry, felt dry, even testing with a bale probe, it probably felt like it came back with dry numbers.”
She said these conditions create fire risks now that hay is being baled.
“We’re getting reports that the dry hay is caramelizing, that it’s heating, and when they open up the bale, it’s sopping wet inside because that stem moisture that they couldn’t feel at the time of baling … is re-wetting the bales.
“I’m hoping it’s not that widespread, but there was so much hay cut. Normally, that window, if people are cutting, it’s haylage or baleage and it’s absolutely fine.”
Producers should be aware of heat levels and use a thermometer rather than a hay moisture probe to check temperatures. A sweet smell or musty odour are signs that hay should be checked.
“If producers have dry hay, I would really encourage them to be checking the temperature on that hay daily,” said O’Reilly.
“Anything that’s above 52 degrees Celsius, that’s unusual. Anything that’s above 65, any year we would say check that one daily. Watch that temperature.
“This year, just because this moisture content thing is so unusual, I would encourage anyone that harvested first cut during the last couple weeks of May to be checking that every day for the next two to three months, just in case that temperature starts to climb.
“At 70 degrees, you need to start checking that every four hours, because if that temperature is going to climb any higher, it could climb fast. If it starts approaching 80 degrees Celsius, call the fire department.”
While risk in dry hay comes from too much moisture, risk in silos comes from too little. If siloed forage is below 40 per cent moisture, it may enter the spontaneous combustion cycle. Rapid wilting conditions during the last two weeks of May could have resulted in haylage stored too dry.
Silos should be checked regularly to ensure doors are airtight. Dry silage combined with fresh air can lead to fires.
“Making dry hay is like dehydrating. Like, raisins last forever, right? Because you pulled all the water out. Hay making is very much like that. We’re preserving it by removing water,” O’Reilly said.
“On the other side of the coin, when we’re making silage, that’s fermentation. We’re pickling that forage. So, you need enough moisture in there to keep it an anaerobic environment, to enable a low pH drop, because that acidity and the lack of oxygen are what pickles forage.”
O’Reilly noted silo fires can be difficult to detect, so use of infrared thermometers can help.
Silo fires more complex
Silo fires can also be more complicated to deal with.
“Those are fires that you need the fire department on hand to handle,” said O’Reilly.
Knowing moisture content is one of the best ways to prevent forage fires, and is easily done with a moisture tester or by drying and testing a sample using a microwave oven.
Instructions on using a microwave to test moisture can be found at OMAFRA’s Field Crop News website.
Perth fire chief Bill Hunter said he thinks farmers have become more aware of hay fire risks in recent years. However, he still recommends checking moisture levels. Such fires often require lots of firefighter labour to contain.
Hunter’s fire department offers free inspections to farms and has developed a safety program that has been adopted across Ontario and parts of the U.S.
“We know how hard farmers work to purchase the livestock and the buildings and the equipment, and if we could help them help themselves by not having a fire, that’s just a win for everybody,” he said.
He encouraged farmers to speak with local fire departments about concerns or spend a few minutes watching videos on farm fire safety. They are available on department websites.
He also suggests that farmers check exhaust fans for dust, make sure no exposed wires pose a risk and ensure the addresses of barns are posted and clearly visible.
“I think that we can all work together to reduce the number of fires on farms all across the province,” he said.