Grain farmers preparing for fall harvest should review their gain handling system and grain drying procedures. A major way to keep grain dry and healthy is aeration. Blowing ambient air through grain storage bins has been used for decades to maintain the quality of grain by keeping it cool, as well as to manage stored insect pests. Pressure aeration uses fans to push ambient air from the bottom of the bin upwards, while suction aeration involves reversing the fans to pull air from the top downward. But, the question of which is better has not been answered.
To find out, USDA entomologist Frank Arthur and agricultural engineer Mark Casada experimented with storage bins whose grain masses were cooled with either pressure aeration or suction aeration. The researchers conducted two eight-month trials using six metal storage bins with perforated floors and grain storage capacities of 1,250 bushels of wheat. Stored insects examined in the study were rusty grain beetles, foreign grain beetles, hairy fungus beetles, red flour beetles, saw-toothed grain beetles, rice weevils and lesser grain borers.
The data showed that, during the summer, suction aeration cooled the stored wheat's upper portion, or "surface zone," more quickly than pressure aeration, and the difference correlated to fewer insect pests. The researchers believe one expected benefit to using suction aeration could be reduced reliance on the fumigant phosphine to control insects. Larger-scale studies are needed.