There's a chill is the air now and that's good because you need to cool corn in storage down to 25-30 degrees to prevent spoilage over winter, says Ken Hellevang, NDSU Extension grain storage specialist.
Running the fan 24 hours per day will cool the corn to roughly the average outdoor air temperature. If the daily high is 60 degrees and the low is 35 degrees, the average is about 48 degrees, he says.
Operating the fan just during the coolest 15 hours of the day will permit cooling the corn to a lower temperature but will take longer. The final temperature if operating the fan from about 7 p.m. until about 10 a.m. might be about 42 degrees, assuming a high of 50 and a low of about 35 degrees during the fan operation.
"Even though this difference seems small, a 10-degree decrease in grain temperature will roughly double the allowable storage time," Hellevang says.
To estimate the time required to cool the corn, divide 15 by the airflow rate. For example, an airflow rate of 0.2 cubic feet per minute per bushel will cool the corn in about 75 hours (15 divided by 0.2). This cooling could take place during five nights of operating the fan 15 hours per night or during three days of operating the fan 24 hours per day.
Once the corn has been cooled, turn the fan off until the next cooling cycle.
Without aeration, corn should be placed into storage at 60 degrees F or cooler and the temperature monitored closely. Respiration heating and solar heat gain on the bin may cause the grain temperature to increase.
Moisture migration will occur when the grain temperature is more than 20 degrees warmer than the outdoor air temperature, so moisture migration is more of a problem in bins without aeration for cooling the grain. Convection currents will flow down the bin wall and up through the center of the bin, causing a moisture increase in the top center of the stored grain.
"Be prepared to move the grain if problems develop," Hellevang advises.
Source: NDSU Extension Communications