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ISSUE  10   July 12, 2007

MAINTAIN GRAIN QUALITY IN STORAGE

Harvest will be upon us before we know it. Grain quality can be maintained in storage if managed properly. It is a wise investment of time to spend a few hours to maintain the $40,000 to $80,000 value of grain stored in a 20,000-bushel bin.

The following steps are recommended for preparing a bin for storage:

  1. Repair any holes that may allow water to enter. Look for holes by looking for sunlight coming into the bin. However, do not seal openings intended for aeration.
  2. Clean the inside of the bin using brooms and/or a vacuum.
  3. Examine the inside of aeration ducts for debris and insects.
  4. Service the aeration ducts, fans and vents to ensure proper operation.
  5. Clean around the outside of the bin.

More information about dry grain aeration and grain handling and storage is available from two publications: "Dry Grain Aeration Systems Design Handbook," MWPS 29; or "Grain Drying, Handling and Storage Handbook," MWPS-13. Both are available through MidWest Plan Service. As a further value, these books are available in a grain handling package along with "Managing Dry Grain in Storage," AED-20 and "Low Temperature and Solar Grain Drying Handbook," MWPS 22. The four publications together are a great reference set and available for $40 for the bundle. For more information go to www.mwps.org, email mwps@iastate.edu, or call 800-562-3618.

Grain stores best when it is dry, clean, and cool. Weed seeds and fine foreign material, which are usually wetter than the grain, will accumulate in the center when loaded into a bin, causing storage problems. This material should be removed from the grain. Use a grain cleaner before storage; unload some grain using a center take out after the bin has been filled, or distribute the material while filling the bin.

Temperature plays an important role in grain storage. The optimum temperature for insects is between 70 F and 90 F. Therefore, grain should not be stored at this temperature. Cooling below 70 F reduces insect reproduction and feeding activity, and cooling below 50 F causes the insects to become dormant. The optimum temperature for mold growth is also about 80 F. Mold growth is extremely slow below 30-40 F. The expected grain allowable storage time is approximately doubled for each ten degrees that the grain is cooled.

Aeration should be used to cool the grain whenever outdoor temperatures are 10-15 F cooler than the grain. It should be cooled to a temperature of about 20-30 F in northern states and 30-40 F in southern states for winter storage. The time required to cool grain weighing 56-60 pounds per bushel using aeration can be estimated by dividing 15 by the airflow rate. For example, the grain will cool in about 75 hours using an airflow rate of 0.2 cubic feet per minute per bushel. Air takes the path of least resistance, so cooling times will vary in the storage. Measure grain temperature at several locations to assure that all the grain has been cooled.

Stored grain must be monitored so insect infestations or grain spoilage can be detected before serious losses occur. Check stored grain bi-weekly during the critical fall and spring months when outside air temperatures are changing rapidly and during the summer. After the grain has been cooled for winter storage, check the grain at least monthly during winter months while outside temperatures are below 40 degrees. Check and record the grain temperature and condition at several locations. The temperature history can be used to detect grain warming, which may indicate storage problems. Look for indications of problems such as condensation on the roof or crusting of the grain surface. Probe to examine grain below the surface. Bring a grain sample indoors if the grain temperature is below 50 degrees; allow it to warm to room temperature, then place the grain on a white surface, and examine for any insect activity. Fumigation is not recommended when grain is stored at temperatures below 60 degrees. Most storage problems can be controlled during the winter by cooling the grain.

Ken Hellevang
NDSU Ag Engineering


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