As outdoor temperatures rise, the risk to stored grain rises as well. Ken Hellevang, North Dakota State University Extension agricultural engineer and grain drying expert, offers these steps to help prevent grain from spoiling:
Aeration fans. Periodically run aeration fans to keep the grain temperature near or below 30 degrees F until the grain is dried if it exceeds recommended storage moisture contents, and below 40 degrees as long as possible during spring and early summer if the grain is dry.
Night air temperatures are near or below 30 degrees in April and 40 degrees in May in the Northern Plains. Soybean oil quality may be affected in less than four months if even 12% moisture soybeans are stored at 70 degrees.
Prevent grain warming. Cover the fan when it is not operating to prevent warm air from blowing into the bin and heating the stored grain. Hellevang also recommends ventilating the top of the bin to remove the solar heat gain that warms the grain. Provide air inlets near the eaves and exhausts near the peak or use a roof exhaust fan.
Plan for ice blockage. Leave the fill and access door open as a pressure relief valve when operating the fan at temperatures near or below freezing. Bin vents can become blocked with frost and ice, which may lead to damage to the roof.
Keep an eye on your grain. Monitor stored grain closely to detect any storage problems early. Check grain temperature and moisture levels and examine samples for insect infestations.
Note: Moisture measurements of grain at temperatures below about 40 degrees may not be accurate. Verify the accuracy by warming the grain sample to room temperature in a sealed plastic bag before measuring the moisture content.
Molds will grow and spoilage will occur in grain bags unless the grain is dry. Because bagged grain temperature will be the same as the outdoor temperature, the grain will deteriorate rapidly as outdoor temperatures increase unless it is at recommended summer storage moisture contents. Grain bags that run east-west will have solar heating on the south side, which creates a temperature variation across the bag that will move moisture to the north side of the bag.
Prevent spoilage. Dry corn to 13% to 14% moisture for summer storage to prevent spoilage. Dry soybeans 11% to 12%, wheat to 13%, barley to 12% and oil sunflowers to 8%.
Prevent deterioration. Dry corn that’s more than 21% moisture and soybeans that are more than 15% moisture in a high-temperature dryer because deterioration occurs too rapidly at warmer temperatures to use a natural air drying system. The allowable storage time of 22% moisture corn is about 190 days at 30 degrees but only 30 days at 50 degrees.
Stay safe. Be aware of safety hazards associated with handling grain and apply recommended safety practices.
Make sure the natural air drying fan airflow rate is at least 1 cubic foot per minute per bushel (cfm/bu) when drying corn and that the initial corn moisture does not exceed 21%. Start the fan when the outdoor temperature averages about 40 degrees.
- Use an airflow rate of at least 1 cfm/bu to natural air-dry up soybeans than are less than 15% moisture. Start the fan when the outdoor temperature averages about 40 degrees.
- Use an airflow rate of 0.75 cfm/bu for up to 15% moisture sunflowers. The drying should start when outdoor temperatures average about 40 degrees.
- Use an airflow rate of at least 0.75 cfm/bu to natural air-dry wheat that’s less than 17% moisture. Start drying when the outside air temperature averages about 50 degrees.
- Use an airflow rate of at least 0.75 cfm/bu to natural air-dry barley that is less than 16% moisture.
“Some of the allowable storage life was used during the fall before the grain was cooled to near or below freezing, so there is less time for spring drying before deterioration occurs,” Hellevang says. “This is particularly important for malting barley, where germination can be lost, so using a higher airflow rate to reduce the drying time is encouraged.”
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