Expert refutes recent research into grain drying

More information needed | PAMI official 
isn’t ready to rule out daytime drying

A grain-drying expert from the Prairie Agricultural Machinery Institute says producers shouldn’t dry grain only at night, contrary to research findings from the Indian Head Agricultural Research Foundation.

Joy Agnew, project manager of agricultural research services with PAMI in Humboldt, Sask., told the Manitoba Canola Growers Association annual meeting in Brandon that grain growers shouldn’t act on the conclusions of the IHARF research, which found running grain bin fans only at night is much more efficient than operating fans 24 hours a day.

“Don’t do anything until there is more definitive results,” said Agnew. “Do not dry only at night.”

Ron Palmer, a retired University of Regina professor, reviewed IHARF data on temperature and relative humidity inside grain bins to determine how much moisture left a grain bin, hour by hour, as a fan ran 24 hours per day.

Based on his analysis, Palmer determined most of the moisture leaves the bin at night and running the fan during the day can actually put water back into the bin, retarding the drying process.

“We’re putting water back in by continuous drying. Pounds and pounds of it,” said Palmer, an electrical engineer who developed auto-steering systems for agriculture.

He suggested that daytime drying was ineffective because the fan pushes warm and moist daytime air into the bin. The cold grain inside the bin cools the warm air, transferring the moisture in that warm air to the grain.

After analyzing Palmer’s research, Agnew said she had no quarrel with the data.

“I have seen their numbers and I agree that they were getting more moisture loss during the evening hours than the daytime hours,” she said.

“But I do question their conclusion that it makes more sense to only turn your fans on at night.”

The IHARF conclusions are based on studies where grain bin fans ran 24 hours per day.

Agnew said she had told IHARF researchers to conduct side-by-side studies, with one fan running 24 hours a day and another running only at night, before releasing their conclusions.

She said she won’t accept the dry at night recommendation until IHARF releases results from side by side trials.

Nonetheless, she said it is true that nighttime air is drier because cooler air can hold less moisture than warmer air. Therefore, the drier nighttime air could potentially pull more moisture out of the bin.

However, Agnew said such a process is contingent on the temperature of the grain inside the bin.

“Their theory of more moisture loss at night depends on the grain being warm,” she said.

“If you run the fans only at night, you’re not going to have a warm grain mass and you’re not going to see that same kind of more noticeable loss at night.”

Ron Krahn, a producer from Rivers, Man., who listened to Agnew’s presentation in Brandon, is also concerned about the IHARF research.

“It flies completely opposite to anything we’ve ever thought about grain drying,” he said.

“I think it has created a lot of producer confusion. I can’t argue with their numbers … but it doesn’t pass the smell test.”

IHARF executive manager Danny Petty said the foundation plans to conduct drying trials with fans running all day compared to fans running at night but is waiting for funding from the Western Grains Research Foundation.

Palmer said farmers should run the fan only when the grain temperature is greater than the ambient temperature.

“If it is not convenient to measure the temp of the grain and the air, then my recommendation would be to run the fan when it is most likely that the ambient air temp will be less than the grain temp,” which would likely be at night, he said.

Palmer said he hasn’t heard criticism or comments from grain drying experts regarding his findings. As well, he doesn’t consider himself to be an expert in the field. His conclusions are based solely on the IHARF grain drying data.

“The data that we collected over four years indicates that drying conditions exist when the grain is warmer than the ambient air, and that is most likely to occur at night,” he said. “That’s what the data says.”

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