Rural fire services across the country are warning about the dangers of high moisture content in hay as farmers are cutting, baling and storing it in this season’s warmer conditions.

Although there have been wetter than usual summers over the past three years, in Victoria alone the Country Fire Authority still responded to almost 52 haystack-related fires between July 1, 2022 and June 30, 2023.

Confirmation of El Niño conditions, with hotter and drier forecasts, means this year will have elevated risks of fire ignition and spread, including the risks of spontaneous combustion.

CFA chief officer Jason Heffernan said if hay is baled with high moisture content and is green, it can heat up like compost, which can lead to spontaneous combustion weeks or months later.

“Farmers who have decided to carry on with hay production need to be extra vigilant this year to make sure conditions are right for making hay and for the future storage and transport as well,” he said.

“Hay fires are a real threat to properties and stock in primary production areas.

“Whether you’re a seasoned hay grower or switching to hay this year, it’s imperative to take care of your hay and crops this fire season.

“Consider the storage of your hay to avoid spontaneous combustion which can lead to ignition.”

When hay is either not properly cured and dried out before baling, or not stored to protect it from rain or damp conditions, moisture content in the bales is then higher than the recommended level.

If stored in environments with high temperatures and little airflow, a biological reaction could lead to a fire.

Haystack fires can also start easily from lightning strikes or sparks from equipment.

“You should regularly monitor your haystacks by using a temperature probe or a crowbar to detect heating hay,” Mr Heffernan said.

“Signs of heating hay can include steam rising from the stack or unusual odours like burning, must, pipe tobacco smell or a caramel smell.

“By being vigilant, you’re protecting yourself from the financial impact of losing valuable fodder and protecting your property and family from the potential danger of hay fires.”

Haystack tips

– Ensure hay is well-cured before baling.

– Know the history of the hay you purchase.

– Keep haystacks to a limited size and separate your haystacks.

– Monitor moisture and temperature of your hay regularly.

– Watch for unusual odours such as pipe tobacco, caramel, burning or musty smells.

– Store hay in separate stacks or sheds away from farm equipment and other buildings.

– Keep your hay dry. Protect it from rain, leaking roofs or spouts, and run-off. Cover stacks with tarps or hay caps.

– Don’t stack hay right to the top of a hayshed. Allow some air to circulate at the top — this helps to carry away moisture.

Check the temperature

Use a thermometer in a probe or insert a crowbar into the middle of the stack for two hours.

– Less than 50°C: You can handle the crowbar without discomfort. Check the temperature daily.

– 50°C to 60°C: You can only handle crowbar for short time. Check the temperature twice daily.

– 60°C to 70°C: You can touch bar only briefly. Check the temperature every two to four hours. Move hay to improve air flow.

– Over 70 °C: The crowbar is too hot to hold. This has the potential for fire. Call 000 immediately. Avoid walking on top of the haystack. At this stage, pulling apart the hay may provide the oxygen it needs to ignite.

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