Grain harvest is in full swing, but it's not too late to review on-farm grain storage principles.

Phillip Glogoza and Dave Nicolai, crops educators with the University of Minnesota Extension Service, say there are four simple steps to maintain post-harvest quality: sanitation, loading, aeration and monitoring the grain.

1. Sanitation. Be sure that the storage structure and grain handling equipment (conveyors, wagons, trucks, elevators) are free of leftover grain. In addition to cleaning the bin, keep areas on the outside of the bin clean. Debris and grain spills outside the bin encourage rodents and insects, which can then move in through openings. Keep weeds from growing around bin areas – these sites are ideal for pests to hide. On the inside, sweep or vacuum grain dust and old grain from floors, walls and ceilings where hiding places exist for stored grain insects. A common rule-of-thumb is, "If you can tell what has previously been in the bin, it’s not clean."

After cleaning and repairing bins, use a residual bin spray to treat the bins at least two weeks before filling if insects are active. It's better to treat during the warmer months when insects are active.

2. Combining and loading into storage. Grain harvested with a clean and properly adjusted combine should also be run through a grain cleaner to further remove fine materials on which insects can feed. In addition, a grain distributor is extremely helpful – it spreads fine material uniformly across the grain mass.

When loading, you want to create a grain mass that's clean, dry and uniform – without foreign material. Plan to protect against stored grain insects by using a grain protectant if grain is to be stored for a year or more.

Immediately after the bin is filled and the grain leveled, apply a surface treatment of an approved grain protectant. The surface treatment will help control insects that enter the grain through roof openings.

3. Aeration. In the fall, and with any bin that holds more than 2,000 to 3,000 bu., aerate to cool the stored grain and create a better storage environment.

"We should be able to cool grain to temperatures below 50 degrees [Fahrenheit] by gradually cooling the grain through the fall," Glogoza says. "Insect activity is reduced at this temperature."

Keep grain temperature less than 50 degrees F at all times of the year. In the Upper Midwest, aerate to cool grain to 20-30 degrees F for winter storage.

4. Monitoring. Check stored grain regularly for temperature, moisture, insects and molds. Inspect stored grain every seven to 14 days when either outdoor or grain temperatures are greater than about 50 degrees F. But if the grain is in good condition and has been cooled to less than 30 degrees, you can increase the inspection interval to once every three to four weeks during cold weather.