There is a critical need for grain storage in North Dakota, as elevators are telling farmers they will not be able to accept soybeans due to lost storage space caused by summer storms.

“All storage options should keep the grain dry and provide adequate aeration to control grain temperature,” says Ken Hellevang, professor emeritus and retired North Dakota State University Extension agricultural engineer.

Grain must be at the recommended storage moisture content and cool when placed in alternative storage facilities because providing adequate, uniform airflow to dry grain or cool grain coming from a dryer is not feasible.

When considering alternative grain methods, it’s crucial to keep some key storage factors in mind.

Recommended grain moisture content

The length of time the grain will be in storage and the outdoor temperatures during the storage period determine the recommended grain moisture content. The recommended short-term storage period is when both the grain and outdoor temperatures are below 40 degrees Fahrenheit — typical of late fall and winter. Long-term storage assumes storage at warmer temperatures that occur during spring and summer.

The following are recommended moisture contents: corn, 15%-16% (short-term) and 13%-14% (long-term); soybeans, 13% (short-term) and 11%-12% (long-term); oil sunflower, 10% (short-term) and 7%-8% (long-term); malting barley, 12%; and wheat, 13%.

Structural issues of grain stored in buildings

Grain pushing against walls can damage buildings not built for grain storage. The wall must be anchored securely, and its structural members must be strong enough to transfer the force to the building poles or support structure without breaking or excessive bending.

“Typically, you’ll need additional poles and a grain wall to support the grain force in a pole building,” says Hellevang. “Hire an engineer to complete a structural analysis, or have a contractor follow exactly the building company’s recommendations to prevent a structural failure.”

Before placing grain in a building previously used for grain storage, look for anything out of alignment, such as wall bowing and distortions in the roofline. Bowing or bending indicates that the load on the building exceeded the load for which it was designed and built. This weakens the structure. Also examine connections for separation or movement and add a gusset or splice to reinforce the connection if necessary.

Storing in bags

Storing grain in poly bags is a good option, but it does not prevent mold growth in damp grain or insect infestations. Place grain in the bag at no more than the recommended storage moisture content based on the outdoor temperatures during the potential storage period. Heating and grain spoilage will occur if the grain exceeds a safe storage moisture content.

Grain in bags cannot be aerated to control the grain temperature. The average temperature of dry grain will follow the average outdoor temperature. If the monthly average temperature is 60 degrees, the average grain temperature will be 60 degrees.

Hellevang provides additional bag storage tips:

• Select an elevated, well-drained site for the storage bags. Run the bags north and south so solar heating is similar on both sides. Sunshine on just one side heats that side, which can lead to moisture accumulation in the grain and spoilage on the cool side.
• Monitor the bags for damage. Wildlife can puncture the bags, allowing moisture in, which can lead to spoilage and the grain smell being released, which attracts more wildlife.
• Monitor the grain temperature at several places in the bags.
• Never enter a grain bag because it is a suffocation hazard. If unloading the bag with a pneumatic grain conveyor, the suction can “shrink wrap” a person.

Grain piles

Grain placed in piles needs to be dry and cool, says Hellevang.

Precipitation is a severe problem for uncovered grain because grain is very porous. A 1-inch rain will increase the moisture content of a 1-foot layer of corn by 9% — from 14% to 23%. This typically leads to the loss of at least a couple of feet of grain on the pile surface, which is a huge loss.

For example, a cone-shaped pile 25 feet high contains approximately 59,000 bushels of grain. Losing just 1 foot of grain on the surface is a loss of about 13% of the grain — $39,000 if the grain value is $4 per bushel and $78,000 at $8 per bushel. Aeration and wind blowing on the pile will not dry wet grain adequately to prevent spoilage.

Use a cover to prevent water infiltration. Drainage, moving water away from the pile, is critically important to the success of any grain storage. About 25,000 gallons of water will run off an area about 100 by 400 feet during a 1-inch rain. This water must flow away from the grain and the area next to it.

“When determining a location for a pile, examine the entire area to ensure that flooding will not occur during major rain events,” advises Hellevang.

The outdoor ground surface where grain will be piled should be prepared to limit soil moisture from reaching the grain. The storage floor should be higher than the surrounding ground to minimize moisture transfer from the soil into the grain. Make sure the ground surface is crowned so moisture drains out and away rather than creating a wet pocket that leads to grain deterioration.

Grain pile covers

A combination of restraining straps and suction from the aeration system holds grain covers in place.

Provide adequate airflow through the grain to control grain temperature. The goal is an adequate airflow rate to cool the grain as outdoor temperatures cool. Place properly sized and spaced ducts under the pile on the ground to pull air through the grain. A rule of thumb is that the duct spacing should be less than the grain depth.

Some storage options use a perforated wall for the air inlet.

“Minimize the amount of open area so the air does not ‘short-circuit’ to the fan,” says Hellevang.

Place perforated ducts on the grain under the cover to provide a controlled air intake for the aeration system and to provide airflow near the cover to minimize condensation problems under the cover.

Wind velocity determines the amount of suction needed to hold the cover down. Some control systems measure wind velocity and start fans based on the wind speed. Backup power can hold the cover down during power outages.

For grain piles with bunker or bulkhead walls, the walls should be examined for anything out of alignment. Any twisting, flexing or bending of a structural member may lead to failure. Also look for separation or movement in connections and material deterioration.

Cooling stored grain

Cool grain with aeration to extend the allowable storage time and reduce the potential for insect infestation. Temperatures below about 60 degrees Fahrenheit reduce insect reproduction. Insects are dormant below about 50 degrees, and extended exposure to temperatures below about 30 degrees can kill insects.

Cooling grain as outdoor temperatures cool will reduce moisture migration and the condensation potential near the top of the grain pile. Also, the grain should be cooled because grain moisture content and temperature affect the rate of mold growth and grain deterioration. The allowable storage time approximately doubles with each 10-degree reduction in grain temperature.

Aeration ducts need to have perforations sized and spaced correctly for air to enter and exit the ducts uniformly and obtain the desired airflow through the grain. The maximum spacing for aeration ducts is equal to the grain depth to achieve acceptable airflow uniformity.

Stored grain lifespan

Grain has an acceptable storage life before the quality is reduced enough to impact its value. Allowable storage time is cumulative, so consider the amount of storage life remaining when making management decisions.

For example, if corn is stored at 14% moisture and 60 degrees for two months (November-December), then cooled to 40 degrees for four months (January-April), then stored through the summer months (May-August) at 70 degrees, approximately 90% of the storage life has been used.

For more information, including allowable storage time tables, visit ndsu.ag/altgrainstorage.

NDSU Agriculture Communication – Sept. 10, 2025

Source: Kenneth Hellevang, 701-261-9869, kenneth.hellevang@ndsu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu