Despite farmers’ best efforts, sometimes hay is baled too wet, which creates a significant fire risk.
Agriculture Victoria northern dairy manager Brett Davidson said reasons behind this could include poor curing weather, nodes and seed heads still wrapped in the flag leaf sheath not being cured enough, or incorrectly calibrated or improperly used moisture meters.
“As a result, there is potential the forage being baled could be two to five per cent higher in moisture than it should be for the type of bale being made,” he said.
Mr Davidson said large rectangular bales needed to be two per cent drier (12 to 14 per cent moisture) than large round bales (14 to 16 per cent), which themselves needed to be two per cent drier than small square bales (16 to 18 per cent).
“This is due to their high density or large volume to surface area for the large rectangular and round bales,” he said.
“Leaving wide windrows behind a mower-conditioner, tedding immediately after mowing (tedders will substantially speed up curing), and using a form of hay preservative will all increase the curing rate of hay.
“While these options add to the cost of hay making, it will be well worth the additional expense for high quality forage.
“Occasionally however, some of the hay will end up in the stack that has not been cured well enough.
“It is vitally important to regularly monitor the stack from week one after baling, for signs of heating.”
Monitoring can include looking for:
● Dampness on the top of bales;
● Steam rising from the haystack;
● Moisture build-up on roofing iron or under tarps of outside stacks;
● Unusual odours (e.g. pipe tobacco, caramel, burning, musty);
● Slumps in the stack; and
● Corrosion on the underside of a tin roof.
Mr Davidson said unfortunately much of the heating would occur in the stack's centre, which was difficult to pick up.
“A crowbar pushed into the stack as far as possible is one strategy that can be used to monitor heat,” he said.
“After a couple of hours, remove the crowbar and feel how hot it is.”
A guide for haystack temperatures include:
● Cooler than 50°C — can handle the bar without discomfort. Check temperature daily;
● 50 to 60°C — Can handle the bar for a short time. Check temperature twice daily;
● 60 – 70°C — Can touch bar only briefly. Check temperature every two hours. Move hay from top layers to improve air flow;
● Hotter than 70°C — Bar too hot to hold. Potential for fire. Avoid walking on top of stack. Put safety precautions in place. Call 000.
Mr Davidson said an alternative monitoring method could be achieved by using thermal couplings, which can be placed into various areas of the haystack at stacking and monitored simply and regularly.
● For more information on hay moisture, visit: agriculture.vic.gov.au