As the spring turns to summer and the canola stored in the bin yard begins to warm up, there’s always a danger that condensation will cause spoilage when the cold oilseed is exposed to warmer temperatures.
“That was the whole point of the study,” said Joy Agnew of PAMI, a research organization that tests farm equipment.
“We thought turning it or blowing air through it would help alleviate that, but that natural convection did not result in any instability or condensation in the bin that we monitored.”
Instead, running the fans caused more problems than just leaving the canola alone.
“We hypothesized that running the fans to slowly increase the temperature of the grain as the spring and summer progressed would be beneficial, but as soon as you put warm air into cold grain, you’re going to have that temperature differential right away in the grain,” she said.
“That also resulted in unstable conditions for a short period of time, after aeration.”
There is a potential for condensation any time cold material is located right next to warmer material.
This is why it’s actually better to leave the canola alone in the bin as temperatures increase — don’t aerate it or turn it as long as the canola is cool, dry and uniform.
“Canola is always that finicky grain,” Agnew said. “You never really know what could cause spoilage, which is why we try to keep it as cool and as dry for as long as possible to minimize that risk.”
The main problem observed in the two years of PAMI’s summer storage project occurred when the warm grain at the top of the bin funnelled down into the centre of the bin when a load was taken out.
“If you’re only turning a portion of the grain, like pulling, say, a third of it out and putting it back on top, it’s mixing up the grain, but you run the risk of having warm grain directly adjacent to cold grain,” she said. “Even in early spring, the grain at the very top is going to be a fair bit warmer than the grain at the centre of the bin.”
If logistically possible, it’s more effective to completely empty a bin if grower chooses to turn it.
“If you are needing to turn it to help even out the temperature or moisture profile — and actually, turning when you are drying in (the) bin with supplementary heating systems is absolutely essential — if possible, pull all of it out and put it in another bin,” Agnew said.
However, pulling out a portion of the bin and putting it back on top is better than just leaving it unmixed when there is variability in temperature and moisture.
“That’s still acceptable, but it’s not going to be as effective as pulling all of it out and putting it into another bin,” Agnew said.
“The main problem with partial turning when you are trying to mix it is you’re not going to get uniform mixing.”
She said it is important to keep a temperature cable in the bin to monitor any temperature increases, even if the canola was cool and dry going into the spring and it’s going to be left alone.
“I’ve heard stories that even in perfect conditions with perfect grain, there was still spoilage,” she said. “You can minimize the risk but you can never eliminate all risk, so just keep an eye on it.”