Recent studies have examined whether it’s better to direct air from above or below as a means of using temperatures of 60 degrees Fahrenheit or below to control insects.
USDA scientists experimented with storage bins whose grain masses were cooled with either pressure aeration or suction aeration. 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.
They 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 that the difference correlated to fewer insect pests. For example, in pressure aeration-cooled bins, 3,290 rusty grain beetles and 8,210 red flour beetles were found in surface-zone traps, versus 662 and 722 respectively in suction aeration-treated bins.
Suction aeration’s rapid cooling of the grain’s surface zone is advantageous because that’s where insects initially infest the grain after flying in from outside. This can reduce reliance on the fumigant phosphine to control insects.
Source:
Applied Engineering and Agriculture; Agricultural Research Service, USDA
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Artwork: Grain Storage Bin Print
