Warm weather this fall has been great for crops to dry in the field before being harvested but has resulted in warm grain going into on-farm storage bins. “Turn on the aeration fans and cool the stored grain as soon as possible to extend storage life,” advises Shawn Shouse, Iowa State University Extension ag engineering specialist in southwest Iowa. This is recommended for both corn and soybeans.
Cool stored grain by running aeration fans any time outdoor air temperatures are 10 to 15 degrees F cooler than the grain. The cooling front will move slowly through the grain in the direction of airflow.
“The air exiting the grain will stay warm until the cooling front gets there,” Shouse says. “With a big fan or partially filled bin, if the airflow rate is around 1 cubic foot per minute per bushel, the cooling should take about 15 hours. With a small aeration fan and an aeration rate of 0.1 cfm per bushel, the cooling will take roughly 150 hours [six days]. As outdoor temperatures decline, repeat the cooling cycles until the stored grain is at 30 to 40 degrees.”
Don’t forget to core bins
Core the grain by removing about 2% of the bin capacity, or about half of the peak height, after the bin is filled. This removes grain that has the greatest concentration of fines and damage, which poses the greatest storage risk, he explains. The result is you’ll have a more uniform grain depth, which also creates more uniform aeration.
Check stored grain weekly through fall and winter. Run the aeration fan and smell the first air exiting the grain. A musty or sour smell indicates mold growth in the grain.
Another way to check stored grain is to use a portable carbon dioxide sensor. This method provides for an even earlier warning of mold or insect activity. Carbon dioxide readings above 600 parts per million indicate potential problems developing in stored grain; readings above 1,500 ppm indicate trouble.
Cooling stored grain
“The bottom line is you should get your stored grain cooled to below 40 degrees as soon as possible after harvesting and putting it in the bin,” Shouse says. “If outdoor air temperatures are still high at harvest, cool the grain in cycles with every 10- to 15-degree fall in average outdoor temperature, and run the fans during cool, dry nights.”
Also, pay attention to the outdoor air dewpoint temperature when running fans and cooling stored grain. Low dewpoints indicate good conditions for cooling.
Contact your ISU Extension field ag engineer for advice if you have questions about drying, handling and storing grain. Also, listen to this podcast by ISU Extension for tips for handling, drying and storing damaged grain. Refer to this bulletin for detailed advice on managing dry grain in storage.