Tips for cooling stored grain

Iowa State University Extension and Outreach
Farm Forum

Recent warm weather in Iowa was great for drying crops in the field, but resulted in warm grain going into farm storage. Cool that stored grain as soon as possible to extend storage life.

Cool stored grain by running aeration fans any time outdoor air temperatures are 10-15 degrees 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. With a big fan or partially filled bin, if the airflow rate is around one cubic foot per minute per bushel (cfm/bushel), the cooling should take around 15 hours. With a small aeration fan and aeration rate around 0.1 cfm/bushel, cooling will take roughly 150 hours (six days). As outdoor temperatures decline, repeat cooling cycles until stored grain is at 30-40 degrees.

Core the bin by removing about 2 percent of the bin capacity, or about half of the peak height, after the bin is filled. This removes the grain with the greatest fines concentration and damage, which poses the greatest storage risk. The resulting more uniform grain depth also creates more uniform aeration. Check stored grain weekly through the 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. Use a portable carbon dioxide sensor for even earlier warning of mold or insect activity. Carbon dioxide readings above 600 parts per million indicate potential problems, and above 1,500 indicate trouble.