Two late and wet harvests in a row have greatly increased canola spoilage — and upped the need to have a conditioning plan in place early on.
“It’s really important to consider this topic now when there is time rather than being in the heat of harvest and having to make decisions,” said Lorne Grieger, a researcher with the Prairie Agricultural Machinery Institute (PAMI).
It’s been a “perfect storm” the past two growing seasons, says the Canola Council of Canada.
“A lot of our rules of thumb are for when things are in our favour,” said council agronomist Angela Brackenreed. “We’ve had these falls where we don’t have the ability to dry with natural aeration and it’s too cold to dry with supplemental heat. We’re taking off canola with unprecedented moisture content of 12 to 15 per cent.
“Unfortunately that seems to be more common every year.”
So what can you do to reduce spoilage?
“We have to take advantage of cold temperatures and get canola as uniformly cold in the bin as possible,” she said. “Be very hands on with turning. Run fans to help break up any hot spot formation, and condition it as uniformly as possible even when you are not drying. And then in the spring start using your supplemental heat with your NAD (natural air-drying) fans as soon as conditions allow and bring that moisture content down.”
Eight per cent is the generally recommended moisture content target for canola, but the oilseed is a bit of a special case when it comes to conditioning. For one, it’s volatile and has a high respiration or ‘sweating’ rate, emphasizing the need to condition as soon as it’s in the bin — even if it’s dry.
“We recommend running fans for at least a few days to take into account its sweating or respiration potential,” said Brackenreed.
Canola also has high resistance to airflow because the seed is small and hence the gaps between seeds are small, too.
“It’s a lot harder to push air through a bin of canola than it is through a bin of wheat, peas or corn,” she noted.
This means horsepower and fan type need to be matched to the size of the bin. But sometimes bins are just too big and shouldn’t be filled to the brim, said Grieger.
“A couple of years ago in Manitoba we looked at an average-size bin — which at the time was 25,000 bushels — and used a 10-horsepower low-speed centrifugal fan setup, which a lot of producers have gone to,” he said.
“We weren’t able to force the air through the bin so we turned that bin from a 25,000-bushel capacity and narrowed it to 17,000 or 17,500 bushels before we started to get the edge of the fan performance.”
Adequate ventilation at the top of a bin is also crucial, he said.
“One square foot per 1,000 cubic feet per minute per bushel (cfm/bu.) is a minimum to have for ventilation at the top of the bin to make sure you can extract the moisture and remove moist air from the bin.”
There are three forms of in-bin conditioning: aeration, NAD and NAD with supplemental heating.
Aeration cools canola but doesn’t remove moisture (between 0.1 and 0.2 cfm/bu. is typically recommended for aerating canola). So most producers use NAD fans, which expel moisture using warm, ambient air blown at minimum airflows of 0.5 to one cfm/bu. That means outside air has to have ‘capacity to dry,’ which essentially means warm air with low relative humidity (RH) — greater than 10 C and less than 70 per cent RH. However, even warm air with high RH does a better job than cool air, said Brackenreed.
“Even if there’s 60 per cent relative humidity in the 30 C air. It still has more capacity to take on moisture than 10 C ‘dry’ air,” she said.
But, of course, you’re not likely to get that sort of heat during a late harvest, which is why many producers are adding supplemental heat to their NAD systems. PAMI calls it “turning poor drying days into good drying days.”
There are no hard-and-fast answers for how hot you should run supplemental heating, but caution is the watchword. The canola council discourages producers from increasing the ambient temperature any more than 15 C to 20 C, although there may be more latitude with higher airflow fans.
“With low airflow rates and high temperatures, producers run the risk of heating the canola closest to the inlet,” said Brackenreed.
“Can we dry faster and more effectively with higher temperatures? Absolutely. But we really just don’t know how that’s going to impact quality and what airflow rates we need to couple with those higher temperatures. That’s something I’m hoping we can dig into more and get some answers for farmers.”
Similarly, there’s no recommendations on the ‘perfect’ setup such as where to place a heater (upstream or downstream from the fan), choice in fuel or choosing between a portable or fixed heater.
“I think we are seeing some indication that some setups may be better than others, but I think it’s maybe a little bit too early to tell,” said Brackenreed.
Turn, turn, turn (and monitor)
Moving canola between bins is also key and the longer canola is stored, the more often bins should be turned, she said.
“If there are any hot spots developing in the bin they can quickly spoil the entire bin. Turning can be a really effective way to break those spots up.”
But it’s a time-consuming process, especially during adverse conditions like those seen this past spring and fall.
“When we had so much harvest to do this spring while there was still damp canola that had sat in the bin over winter, that became a real challenge,” said Brackenreed.
“You need a lot of people power to do all this while you’re also trying to seed and harvest. But canola is an incredibly high-value crop; the potential for spoilage and the financial and economic loss from not being really hands on is huge.”
Producers may be able to minimize bin turnover through careful monitoring and record-keeping. Technology such as temperature cables help but be sure to use them correctly and not rely on them too much,” she said.
“Make sure you look at the manufacturer guidelines such as how many cables you need relative to the size of your bin. It’s important you understand their limitations and understand that they don’t completely take the place of good, hands-on management.”