August 8, 2003

 

Maintain Grain Quality in Storage, NDSU Ag Engineer Advises

With harvest in full swing, a North Dakota State University Extension Service engineer, advises producers to think about storage before they fill their bins. Grain quality can be maintained in storage if managed properly says Ken Hellevang. "It is a wise investment of time to spend a few hours to maintain the $20,000 to $40,000 value of grain stored in a 10,000-bushel bin," he says.

Hellevang makes suggestions for preparing the bin for storage:

Grain stores best when it is dry, clean and cool, says Hellevang. 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, by unloading some grain using a center take out after the bin has been filled, or by distributing the material while filling the bin," Hellevang says.

Hellevang says 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," Hellevang says. Cooling below 70 F reduces insect reproduction and feeding activity, and 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 about 30-40 F," Hellevang says. "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 degrees cooler than the grain. It should be cooled to a temperature of about 20-30 degrees in northern states and 30-40 degrees in southern states for winter storage. Hellevang says 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," he says. "Air takes the path of least resistance, so cooling times will vary in the storage. Measure grain temperature at several locations to assure that the 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, and after a storage history without problems, Hellevang says to 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," he says.

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, place the grain on a white surface, and examine for any insect activity. Most storage problems can be controlled during the winter by cooling the grain, Hellevang says. Fumigation is not recommended at grain temperatures below 60 degrees.

For more information go to www.mwpshq.org or e-mail mwps@iastate.edu for a "Dry Grain Aeration Systems Design Handbook", MWPS 29, or "Grain Drying, Handling and Storage Handbook", MWPS-13, or call (800) 562-3618.

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Source: Kenneth Hellevang, (701) 231-7243, kjh-eng@ndsuext.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu