A large temperature difference between stored grain and the ambient temperature can cause problems for stored grain, but growers need to be careful how they equalize it.
When the temperature warms in the spring and summer, growers with temperature cables in their bins should be monitoring them weekly or biweekly. When temperature differences along the cable is apparent, producers should start turning or aerating their grain, said Blaine Timlick of the Canadian Grain Commission.
“Get it (stored grain) to ambient temperature, and as uniform as possible in temperature. That way you’re going to avoid a lot of those convection currents and mould production, etcetera, when you’re storing this product for a fairly lengthy period of time,” Timlick said.
He said if growers do not have temperature cables in their bins, they should core the bin at least once during the year.
“Meaning pull out about 25 percent of it, taking temperature measurements as you’re doing it, and then just put that grain back in. It’s just a way of turning the grain to help again with that uniformity and temperature,” Timlick said.
He said grain is an extremely good insulator of heat and so it takes a lot of energy to change its temperature.
“So if you have a large bin of grain and it is eight to 10 degrees different than the ambient temperature, you start developing convection currents in it and that will either cause the warm air to move up through the middle if it’s cooler outside than the grain temperature, or vice-versa, if it’s warmer outside than the grain temperature,” Timlick said.
“Even if the grain is as dry as the proverbial popcorn fart it’s going to create condensation on the surface and of course that allows mould growth, and that allows mycotoxin production, for the storage (of) mycotoxins.”
For canola, because it causes so much friction or resistance to the air force in an aeration bin, growers need to be careful to run their fans long enough to completely equalize the temperature within the bin.
“If you only have that air front or different temperature front halfway or three quarters of the way through the bin and you turn the fans off, you’re creating more of a problem then you’re solving,” Timlick said.
“When would I run them (aeration fans)? If it was 30 degrees I wouldn’t be. But if it was around 20 degrees, low 20s, high teens, I would run it until I knew that I had a temperature in the top surface, that is the top 40 to 60 centimetres, that is the same temperature as the ambient temperature,” Timlick said.