Don’t trust grain bin moisture meters when it gets cold, says a grain drying expert from North Dakota State University.
Ken Hellevang said that’s because they stop working accurately and leave farmers with false impressions of what kind of grain they have in store.
“There are many things that can fool the moisture meter,” he told the CropConnect conference in Winnipeg Feb. 17.
When the temperature drops to around freezing, “there’s almost a certainty that the meter is not going to be accurate.”
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That can lead to misreadings of two to four percentage points of moisture, which is a dangerous amount by which to be wrong.
He said an incorrect moisture reading is just one of the risks that farmers face when storing grain.
Farmers need to begin drying as soon as possible after harvest be-cause every degree lower in temperature cuts the ability of the air to dry grain.
Every 11C drop in temperature roughly halves the amount of moisture that air can carry, so farmers need to use warm air soon before the chill of winter strikes.
Hellevang said there’s not much point continuing to aerate grain once it gets down to freezing because drying occurs extremely slowly. Grain stores well over winter at the freezing point and can be dried in the spring.
“I keep getting calls from guys who are running fans when it is extremely cold outside and my comment is always that 20 below F (-30 C) is no better than 20 above F (-6 C).”
However, farmers shouldn’t rush to fire up the fans on the first nice day of spring, Hellevang said. They should wait until the temperature will consistently be 4 C before beginning spring aeration to avoid being hit by spring cold shots. That would leave the grain warmed but not drying.
“If we run the fan for a day, then shut the fan off because it’s cooled off, and leave the sunflowers sitting there at 50 degrees (10 C), we have in-creased the speed at which it spoils,” said Hellevang.
He gave short shrift to the theory, promoted earlier in the day by retired electrical engineering professor Ron Palmer and a handful of others in recent years, that using only cold night air is better than using warm day air to dry and protect grain.
“It totally contradicts science. It totally contradicts reality,” said Hellevang in an interview.
“It doesn’t work that way.”
He said moisture meter misreadings in cold temperatures can be mitigated by taking samples of grain out of the bin, warming them to room temperature for six to 12 hours in a sealed container and then measuring the moisture content.
