Freezing The Bugs In Your Bins
Controlling grain temperature is critical for maintaining grain quality in your bins. Insects moving around and feeding on your stored grain can be controlled by temperature as well. Typical post-harvest aeration cools the grain mass, now it’s time to finish the job by dropping temperatures enough to kill the bugs.
Ken Hellevang is an Extension ag engineer at North Dakota State University. He says once temperatures dip below 50-degrees the insects become inactive, but not dead.
"In the northern states we can cool those stored grains to maybe freezing or just below, so we’re talking 32-degrees," he says. "And, within a matter of a few days, it likely will kill off those insects."
How long will it take to cool the grain down? One rule of thumb is to divide 15 by the airflow rate in the bin, and that will give you a rough estimate of the number of hours it will take to run a temperature change through the grain bin.
"So, for example, if we’re looking at a common aeration airflow rate today of 2/10 cfm (cubic feet per minute) per bushel, we take 15 divided by that," he says. "We’re looking at roughly 70 hours of fan time."
He warns that bin vents could ice over when the aeration system is operated at or near the freezing point. Leave access doors open to serve as pressure relief valves to reduce the potential of damaging the roof.