“The warmer it (canola) is the drier it needs to be to stay stable. It’s that combination of temperature and moisture that’s important.”
– DERWYN HAMMOND
Ed Rempel makes no apologies for his penchant for storing his canola crop dry.
“When it comes to growing canola being paranoid means being profitable,” he said in an interview last week
So Rempel was taken aback when he recently checked a 3,850-bushel unaerated bin over several days and found the temperature of the canola was rising. He removed one load from the bin and two days later the temperature of canola inside remained at 30C. He took another load out and two days later the temperature hadn’t budged.
“I just called in a semi and I took a whole whack of it out,” Rempel said. “Problem solved. But I had to get aggressive with the problem solving. The bin right next to it with no aeration was just fine.”
Rempel says he realized that if some of his canola was starting to heat the same was no doubt happening on other farms.
As the old saying goes, oil and water don’t mix. Canola is high in oil and therefore needs to be drier than cereal crops to prevent spoiling while in storage, the Canola Council of Canada’s Brandonbased agronomy specialist Derwyn Hammond said in an interview.
The key to safe canola storage is making sure the crop is dry (eight per cent moisture or lower) and cool (15C or lower).
“The warmer it (canola) is the drier it needs to be to stay stable,” Hammond said. “It’s that combination of temperature and moisture that’s important.”
Grain buyers consider canola “dry” at 10 per cent moisture, but Rempel prefers seven per cent and doesn’t start harvesting until the crop is nine per cent moisture, presuming it will get drier as the day goes on.
Canola that goes in the bin at eight or nine per cent moisture needs to be conditioned either by aerating it, or pulling loads out and mixing the canola, especially if the crop is 25C or warmer, the Canola Council of Canada said in a recent news release. But if moisture levels are 10 to 12 per cent or higher, farmers should consider heated air drying.
“At this time of year aeration is good for keeping temperatures cool, but if you’ve binned it wet then once daytime temperatures get much below 10C it really slows down the rate of drying you’ll get with just natural air,” Hammond said. “It’s still good temporarily but before you turn the fans off you need to be sure the grain is actually dry.”
The bigger the bin, the more potential for trouble.
“A larger grain mass obviously insulates it more and holds the heat in the centre of the bin for a lot longer,” he said. “Just your ambient cooling won’t work nearly as quickly in a larger structure.”
Bigger bins are difficult to probe properly so fitting them with temperature cables is helpful for monitoring.
Even after conditioning canola, it’s critical to keep a close eye on bins since freshly harvested seed can maintain a high respiration rate for up to six weeks, the canola council says. During this unstable “sweating” stage, there is still risk of canola seed heating or becoming mouldy. Regular monitoring at frequent intervals, particularly until cold temperatures set in, is critical for safe canola storage.
“I’d still look at it every month or so and keep an eye on it,” Hammond said of dry, cool canola in the bin. “But if you know it’s borderline for moisture and went in the bin fairly warm then certainly you need to be monitoring more frequently.”
As for Rempel, he has his aeration fans turned on in the bins that have them.
“I don’t care if it costs $20 for electricity to get that bin cooler,” he said. “It’s cheap at twice the price.”