Is continuous aeration a waste of money, or worse?

Natural aeration might not use hot air in the bin, but it generated some at CropConnect

aeration fans at the base of grain bins

After years of studying the effects of natural aeration on wheat, barley and peas, Ron Palmer of the Indian Head Agricultural Research Foundation says that leaving fans running during the day isn’t just ineffective, it may actually damage the grain in your bin.

“Not only are we spinning our fans for nothing, but it leaves us with fewer safe days,” said Palmer. “There is deterioration going on because we’re actually heating the grain up and wetting it down… which is not good.”

Rather than cooling and drying grain, leaving a fan on continuously can heat grain up and draw moisture in, he said.

Ron Palmer
Ron Palmer photo: Shannon VanRaes

Palmer told producers at CropConnect in Winnipeg last month that the basic rule of thumb is to only run the fan when the outside air temperature is lower than the temperature of the grain. That usually means leaving it on at night and shutting it off in the morning.

“I call it the yardlight rule,” he said. “On at night you are bright, on during the day, you will pay.”

The one exception to the rule is when a bin is first being filled. Palmer advises turning on the fan before the bin is completely full and letting it run until the following morning.

But the former University of Regina professor’s findings are not being embraced by all.

“It sort of contradicts how we’ve been doing things,” said one producer who took in Palmer’s presentation.

Other experts also weighed in on the issue during the annual CropConnect conference.

Ken Hellevang
Ken Hellevang photo: Shannon VanRaes

“It’s more than sort of a contradiction,” said Ken Hellevang of North Dakota State University’s extension service, adding he has asked a wide variety of colleagues and experts to provide their thoughts on the issue. The consensus was that existing methods are the ones to stick with.

“I can’t see that just running the fan at night is going to get us what we want,” Hellevang said.

But Palmer stressed that keeping grain dry and safe isn’t about how it’s always been done, it’s about data.

“When I saw those numbers, I was as shocked as anyone,” he said. “So it’s not me speaking, it’s the data that’s speaking. This isn’t some simulation or some theory, we are observing the data and analyzing it, and this is what it’s telling us.”

More producers have come on board with the concept in recent years.

“When we first introduced this a couple of years ago, it was quite controversial,” Palmer said. “But I think people are starting to accept it more and more.”

It was an abundance of convention and an absence of actual research that led him to study the issue in the first place.

“Producers just turned the fan on and hoped for the best. We didn’t really understand what was happening inside, so we did the best we could,” he said. “But there was a sneaking suspicion for years, that there’s got to be times when that fan isn’t doing anything.”

By monitoring temperature and moisture in the bin on a minute-by-minute basis — looking at air coming into the bin and air exiting the bin — Palmer discovered there was actually a daily cycle of wetting and drying taking place when fans were left running.

Palmer will now expand the scope of his research to examine the effects of fan use on canola.

“We’re looking at bigger bins, we’re looking at different crops, we’re looking at extended periods of time, like in the spring,” he said, adding that large-scale experiments are an essential but difficult step in agricultural research.

“It’s really expensive to set up an experiment like this on a farm scale, where your liability is really huge,” the researcher said. “Who wants to let you fool and play around with their tough grain? This is their livelihood that you’re playing with… but thankfully the experimental farm is set up for this.”

For more on the aeration question

BINcast calculates the best time to run your fans

Ian Nichols of Weather INnovations Consulting (WIN), also says that running fans at the wrong time can add rather than remove moisture from grain. He’s developed a web-based tool called BINcast, which calculates the “equilibrium moisture content” (EMC) for particular grains and conditions.

This Manitoba Co-operator story from August 2013 provides a link to the BINcast program, which allows you to select your location in Manitoba and see a forecast for the best time to run fans for different grains.

About the author


Shannon VanRaes is a journalist and photojournalist at the Manitoba Co-operator. She also writes a weekly urban affairs column for Metro Winnipeg, and has previously reported for the Winnipeg Sun, Outwords Magazine and the Portage Daily Graphic.



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