We don’t really know whether canola in a 25,000-bushel bin stores differently from canola in a 2,000-bushel bin. We don’t know if straight combining reduces or increases canola storage risk. And we don’t know the best way to store canola for 11 months through fall, winter, spring and summer weather changes.
Given that many canola growers have added one or more of these variables to their systems, the notion that no canola is truly safe in storage is probably more important than ever. All bins need to be checked regularly.
The 25,000-bushel question
Larger bins present several potential risk factors that smaller bins do not. Canola on top of canola in a big bin increases static pressure and reduces the amount of air between seeds. Pushing air through these big bins to cool the mass and remove moisture takes more horsepower.
Jason Jones, regional sales manager with Ag Growth International, which owns bin brands Westeel, Twister and Grain Guard, says their top-selling bin sizes are the 25,000-bushel flat-bottom Model 3607 and the 4,900-bushel Model 1805 hopper combo. And he says the market is shifting to even larger hopper bins with 21-foot and 24-foot diameters. Since probing to the centre of these bins is just about impossible, he says most customers install temperature or moisture cables or a combination of both.
“As for the fans, a five-hp high-speed fan can provide enough airflow to maintain the grain in 25,000-bushel bins,” Jones says, but to remove moisture, “we recommend two 30-hp low-speed fans.”
Despite that recommendation, most growers use a 10-hp fan. A complicating factor, he adds, is that most higher-horsepower fans are only available in three-phase, which not every farm site has available.
Ron Krahn has seven 24,000-bushel bins on his farm near Rivers, Man., and he stores canola in them all the time. He has four temperature cables and one 10-hp low-speed fan for each bin. The larger-diameter centrifugal fan is enough to cool canola, Krahn says, but he wouldn’t count on it to do much drying.
“Under certain conditions, we will mix a bit of 11 per cent canola with drier canola in the bin and the fans will even out the moisture,” he says, “but I wouldn’t expect the fans to dry down a bin of canola at 11-12 per cent moisture in time to be safe.”
Greater potential for inconsistency throughout the bin adds to the big-bin risk. Big bins filled over multiple days and fields will have more variability in terms of moisture content, dockage and temperature. Add the staggering fact that one 25,000-bushel bin contains $250,000 worth of canola, and the risk of losing one to heating becomes all the more apparent.
“There hasn’t been any large-scale work that represents the size of bins commonly used in Western Canada, so we just don’t know whether safe storage guidelines are dependent on size,” says Angela Brackenreed, agronomy specialist with the Canola Council of Canada.
Many more months of monitoring
Joy Agnew, a project manager with the Prairie Agricultural Machinery Institute (PAMI) in Humboldt, Sask., completed one season of a summer storage project back in 2014 and will repeat the project again this summer to look at a couple other parameters.
Her year-one results suggested the best way to handle canola stored over the summer months would be to leave it alone. But this was based on canola stored at 6.5 per cent moisture and with the fans turned on during a few very cold winter days. What about canola at 10 per cent moisture and not frozen throughout?
“More information is needed before we know for sure how to reduce summer storage risk in these varying situations,” Brackenreed says.
Straight to the elevator
Ron Krahn still swaths most of his canola. Any canola he straight combines goes straight to the elevator.
When combining swathed canola, his combine’s yield and moisture monitor rarely has more than two percentage points of variability throughout a field. “If the overall moisture is 6.5 per cent, the range might be five per cent to eight per cent,” he says.
But in his experience with straight-combined canola, overall moisture levels are higher and the variability is wider. He had one field where harvested canola ranged from five per cent to 17 per cent moisture. “The average might be dry, but that variability is a huge storage risk,” he says.
Krahn says waiting an extra week to let the crop cure a little more or using pre-harvest spray might help, but that extra week out in the field adds to harvest stress and the spray adds to harvest cost.
Does Krahn’s experience represent the situation for all who straight combine canola? Probably not. Are there situations where straight cut could reduce storage risk? Could be. “We just don’t know yet,” Brackenreed says.
Check and check again
Angela Brackenreed provides the following five tips to keep all stored canola as safe as possible:
- Condition grain to eight per cent moisture or less and 15 C or less.
- Turn the fans on as soon as canola covers the aeration screens and leave them on until canola is conditioned to parameters outlined in Step 1.
- Consider the conditioning and storage challenges for each load coming off the combine. If canola is tough, can natural aeration realistically dry it down? Will the elevator accept it at “x” moisture content or do you need the ability to dry it? Is there higher-than-normal green seed that may increase storage risk even if canola tests dry? Were there patches of weeds or other dockage that may be higher moisture? Was some canola harvested at a lot higher moisture content, potentially creating a high-risk area in a bin that is dry on average?
- Ground truth any devices used for measuring the condition of grain. Test the on-farm moisture meter by taking the same sample to the elevator. Compare results. A moisture meter that is off just slightly could be the difference between safe and spoiled canola.
- Monitor, monitor, monitor. At a minimum, check temperature and moisture a couple times within the first six weeks after harvest, then again at freeze-up and in the spring as conditions warm up. Check more frequently if grain went into the bin hot, at higher moisture or with higher levels of green seed or dockage.