Corn Grain Storage


Grain storage problems can occur due to poor grain quality and poor storage practices. Follow these management best practices to help keep your grain in good condition.



If grain has been dried to the proper moisture content, improper temperature management is the primary reason for spoilage. When the grain temperature in the bin does not remain constant, moisture in the bin can migrate and accumulate in areas, resulting in grain spoilage. Spoilage from moisture migration can occur whenever temperatures vary in the bin, but is more common when warm grain is stored and outside temperatures are cold. In general, no matter what time of year, grain should be maintained within 15-20° F of the average monthly temperature.

Aeration is used to control grain temperature by moving air through the grain. In general, aeration should not be used to dry grain, although the moisture content may slightly change. Aeration is used to cool grain in the fall, or help to warm it in the spring. Grain that is cooled in 10-30° F increments for winter storage should be less subject to mold growth and insect reproduction.

The area of the grain that follows the temperature change through the bin during aeration is known as the cooling or warming zone. One cooling/warming cycle is the amount of time needed to move a cooling/warming zone completely through the bin. Once a cycle has begun, the fan should operate continuously until the zone moves completely through the bin. The time required for one full cycle depends on aeration airflow rate. Generally, two to three full cycles are needed to cool or warm grain to desired storage temperatures.

On-farm storage systems may be equipped to move air between 1/10 cfm (cubic feet of air per minute)/bu to over 1 cfm/bu. The rate depends on bin type, air distribution system, desired storage moisture percentage, and proper management procedures. The time it takes to complete a full cycle depends on the aeration rate and time of year, and can be figured with the following formulas by season:

Fall hours = 15/(cfm/bu)
Winter hours = 20/(cfm/bu)
Spring hours = 12/(cfm/bu)


When temperatures are quickly changing in the fall and spring, be sure to make weekly observations to grain in bins. This can be reduced to every two or three weeks throughout the winter. Establishing a specific day of the week and time of day can make it easier to remember.

Taking multiple grain samples when filling the bin and during storage can help account for variable moistures and reduce the risk of storage molds. Use the highest moisture content value to determine management options that can reduce the risk for storage molds, hot spots, and spoilage. Averaging sample values may not adequately address pockets of grain with higher moisture content.

Keep an eye on the surface conditions, temperatures, and grain condition, and be mindful of different smells, both in the grain and exhaust air. Grain that is crusting, wet, or slimy, as well as  ice or frost accumulation and/or heating can be signs of poor conditions and spoilage. Condensation or frost on the underside of the roof, hatches, and vents on cold days almost always indicate a moisture migration problem. If crusting occurs, stir the surface to break up the crust or if severe, remove the spoiled grain.


Insect infestations can arise from residue in combines, handling equipment, and old grain left in storage. In addition to all other management precautions, be sure to watch for insect activity during regular observation. Some preventative measures that may help prevent insect issues in stored grain include:

  • Cleaning debris from harvesting, handling, and drying equipment, and from inside and outside bins before putting in new grain.

  • Repairing any areas in the bin that may cause leakage.

  • Applying an approved insecticide to surfaces of clean, empty bins before filling.

  • DO NOT put new grain on top of old grain — just a few insects in the old grain can infest the entire bin.


The dangers of grain handling cannot be stressed enough. NEVER enter a bin when grain is flowing and be extremely cautious around all grain handling structures and equipment. Be sure to have safety precautions and emergency plans in place and make them known to all workers and bystanders on the farm.

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