Don’t Forget About Stored Grain This Spring

BROOKINGS, S.D. – As the outdoor temperature rises this spring, stored grains are warming as well. Due to a difficult and wet harvest last fall, many producers in the region chose to store grains much wetter than typical. As a result, special care needs to be taken for these grains as the air temperature rises this spring, explained Sara Bauder, SDSU Extension Agronomy Field Specialist. 
“Grain bins work as solar heat collectors, and the grain inside of them may be much warmer than one expects. If the grain inside gets too hot, and it has not dried down enough, hot spots and grain spoilage can develop,” Bauder said. “Throughout grain storage, but especially during the spring and summer months, producers should check stored grain every week for storage temperature, insect infestations, and mold growth.”
With the changing weather, Bauder said it is ideal to keep wetter-than-recommended stored grains near or below 30 degrees Fahrenheit, during the spring season, until grain reaches recommended storage moisture levels (see Figure 1). 
After grain is adequately dried, it should be kept at or below 40 degrees Fahrenheit through the rest of spring and early summer or as long as feasible. 
“Throughout mid to late summer, it is best to keep the storage temperature for dried grain below 50 degrees Fahrenheit if possible,” Bauder said. “This limits insect activity and potential mold issues.”
See Figure 2 for an explanation of approximate allowable storage time of cereal grains. “Remember, allowable storage time is cumulative, so fall temperature and moisture have a large impact on spring storability,” she explained.
• Cover bin fans when not in use. Fans essentially go through the ‘chimney effect’ where wet, warm air can move into the fan with wind and up, affecting the grain inside.
• Provide an inlet for air near the roof eave and an outlet exhaust near the bin’s roof peak to allow warm air to exit the bin (much like the principles ventilation of a home’s attic). Several vents at the same elevation can still allow heat to remain at the top of the bin without exhaust at the peak or roof exhaust fan.
• Add a temperature sensor near the south wall of the bin to get readings in likely, the warmest part of the bin.
• Periodically run bin fans throughout the spring to help keep grain cool and slow warm up.
• Choose cool summer mornings every two-to-three weeks to run the aeration fan to keep grain cool and push cool air up through warm grain near the top of the bin. If using a moisture meter to check grain, be sure to warm up samples to room temperature in a sealed container for several hours before measuring. 
For more information on selecting fans and determining if your fan is large enough, see the University of Minnesota Extensions’ Fan Selection Tool which can be found at this link: https://bbefans.cfans.umn.edu/
Recommended Airflow Rates
The following recommendations are from Ken Hellevang, North Dakota State University Extension. 
• Corn – The fan’s airflow rate should be at least 1 cubic foot per minute per bushel and the initial grain moisture should not exceed 21 percent. Start the fan when the outdoor temperature averages about 40 degrees Fahrenheit.
• Soybeans – Use an airflow rate of at least 1 cubic foot per minute per bushel to natural air-dry up to 15-16 percent moisture soybeans. Start the fan when the outdoor temperature averages about 40 degrees Fahrenheit. 
• Wheat – Use an airflow rate of at least 0.75 cubic foot per minute per bushel to natural air-dry up to 17 percent moisture wheat. Start drying when the outside air temperature averages about 50 degrees Fahrenheit.
• Sunflowers – Natural air-drying for oil sunflowers requires an airflow rate of 0.75 cubic foot per minute per bushel for up to 15 percent moisture. The drying should start when outdoor temperatures average about 40 degrees Fahrenheit.
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