with Sara
Checking on Stored Grains this Winter
With February just about here, it is a good time to think about the condition of any grains you may have stored this past fall. Although winter temps often make us assume we don’t need to worry about our stored grains, the opposite can be true! According the Ken Hellevang, NDSU Extension Engineer, “More heating occurs on the south wall of a grain bin on March 1 than during the middle of the summer.”
It’s easy to forget about your bins over the winter, but trying to keep them on the ‘to-do’ list is quite vital to keep your commodities in top condition. Keeping grain cool helps reduce insect activity, and suppresses mold that may ruin grain condition. If bins do not have built-in temperature sensors, it is ideal to measure grain temperature at several places along the wall of the bin, near the top surface, and within the middle of the bin. Temperature sensors are nice for checking grain, but several readings are required to get an accurate picture of overall grain temperature. Moisture meters can also be useful, but key factors to an accurate measurement include: make sure the grain sample collected is a good representation of the entire bin (or best possible), and that the sample is put in a sealed container and allowed to warm up to room temperature for several hours before measuring for moisture.
Stored grain with a temp above 55-60°F should actually be inspected once per week. If below 55°F, checking once every two weeks is recommended. Aeration is a common method used to dry grains over winter periods, but reductions are often small (0.25-0.50 percent per cycle) and depend upon many factors like grain moisture, air temperatures/moisture, and length of aeration time. Multiple aeration cycles can reduce grain moisture by as much as 2 percent, but much of the moisture reduction tends to occur in grain closes to the entrance of the fan, leaving grain further away wetter longer. Naturally, any time we can move cool, dry air into a bin, grain temperatures have the opportunity to reduce, increasing potential storage time.
Winter Stored Grain Tips:
• Cover bin fans when not in use. Fans go through the “chimney effect” where wind can move moist air into the fan and travel upwards, affecting grain in the bin. This can be helpful during cold, dry periods but not at all helpful during snow or rain events.
• Provide an inlet for air near the roof eave and outlet exhaust vent near the roof peak to allow warm air to exit the bin (like the principles of an attic). Many vents at the same elevation can allow heat to remain at the top of the bin if no exhaust outlet or fan at the peak is present.
• Monitor grain often to detect changes in temperature, odor, insect pest presence, or molds. Weekly monitoring is recommended, but any amount of checking is better than none!
Recommended Airflow Rates (from Dr. Ken Hellevang of NDSU Extension):
• Corn: The fan airflow rate should be at least 1 cubic foot per minute per bushel (abbreviated as cfm/bu) 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 cfm/bu to natural air-dry up to 15 to 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 cfm/bu 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 cfm/bu for up to 15 percent moisture. The drying should start when outdoor temperatures average about 40 degrees.
For more information on selecting fans and determining if your fan is large enough, see the University of Minnesota Extensions’ Fan Selection Tool (https://extension.umn.edu/ corn-harvest/selecting-fans-and-determining-airflow-grainbins). For more information on fall and winter grain storage visit https://extension.sdstate.edu/few-considerations-fall-andwinter- grain-storage.
References/Resources:
• Hellevang, Ken. Keep Stored Grain Cool During Spring and Summer. North Dakota State University Extension Service. 2018.
• Hellevang, Ken. Proper Spring Grain Drying and Storage Critical. North Dakota State University Extension Service. 2019.
• Scott, Jessie. 8 Tips for Long-Term Grain Storage. Successful Farming. 2018.
• Selecting Fans and Determining Airflow for Grain Bins. University of Minnesota Extension. 2018.
SDSU Extension is an equal opportunity provider and employer in accordance with the nondiscrimination policies of South Dakota State University, the South Dakota Board of Regents and the United States Department of Agriculture. Learn more at extension.sdstate.edu.