October 24, 2001

As corn and soybean harvests wind down in Kentucky, crop managers are reminded to watch grain in the bin as diligently as they scouted it in the field to protect product quality.

When you consider that the value of grain held in a typical farm storage bin is anywhere between $15,000 and $100,000, depending on bin size and type of crop, there is abundant motivation to check it often, said Sam McNeill, agricultural engineer with the University of Kentucky Cooperative Extension Service.

Remember grain quality will not improve during storage. The best managers can hope for is to keep the quality of grain the same during storage. McNeill offers the following reminders to help stored grain managers and operators preserve corn and soybean quality and stay safe while doing so.

1. Spilled grain attracts birds, rodents and insects. Remove small grain piles that tend to accumulate during harvest around bin doors, traffic areas, and grain transfer points (receiving pits and hoppers) using brooms, rakes, shovels or wet-dry vacuums.

2. A bin filled to the peak will not have uniform airflow. Unload the top cone of grain in the bin to form a v-shaped surface. Coring bins will remove the majority of fines and broken grain that tend to accumulate near the center of the pile and choke airflow. This practice obviously improves airflow through the grain, which reduces the chances of spoilage, and helps aeration fans work more efficiently.

3. Seal the unloading auger tube opening with plastic and duct tape immediately after coring the bin to provide a barrier for insects.

4. Run aeration fans once a month during the fall to cool grain. Target temperatures throughout the bin should be within five to 10 degrees of the average outside monthly air temperature. In October the average air temperature is 60 degrees; in November, 50 degrees and in December, 40 degrees.

5. Run fans long enough during each aeration cycle to complete the job. This may take anywhere from 12 to 15 hours up to 120 to 150 hours, depending on the ratio of fan to bin capacity and the number of fine material and broken grain within the bin.

For example, A 10-horse power fan on a 10,000 bushel bin will require 12 to 15 hours of fan operation, which can be operated continuously or intermittently (in two 6 to 7.5 hour periods) when the average outside air temperature is in the desired target temperature range. Fan operation can be twice as long for overfilled bins — which can double the energy cost of aeration.

6. Seal fans with plastic when not in operation to prevent invasion by mice and other rodents and to prevent convection drafts in the bin which exposes grain along the floor to wide temperature variations during the fall.

7. Inspect grain once a month during the fall to be sure conditions remain stable. Look for damage from condensation or leaks around roof vents, access hatches, and temperature cables. Frequent inspections help managers locate small problems before they become large ones.

8. Educate all farm workers about the dangers involved in flowing grain and the health hazards associated with exposure to grain dust. Always lockout motors to unloading augers before entering a bin.

9. Be sure that workers wear properly fitting masks when inspecting stored grain to protect lungs and air passages from dust and potential mold spores. Exposure to grain dust can result in flu-like symptoms. Repeated exposure can lead to irreversible damage to lung tissue (farmer's lung).

10. Consider installing temperature cables to help monitor storage conditions or fan control equipment to automate and track fan operation.

Energy costs

Energy costs for aeration can be estimated by multiplying the fan horsepower by the hours of operation and the cost of electricity. With an electrical charge of 7 cents per kilowatt-hour, a 10 horsepower fan operated for 15 hours will cost $ 10.50 ($0.07 x 10 x 15).

If three aeration cycles are desired in the fall, the energy costs for a 10,000 bushel bin is 0.32 cents per bushel ($ 10.50 x 3/10000). Note that the energy cost for a smaller fan running proportionately more hours is the same.


Sam McNeill, (270) 365-7541