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Corn Drying and Storage Facts

corn, drying corn, aeration, grain bag, moisture meters

Submitted by Craig Askim, Extension Agent, Agriculture and Natural Resources

Corn Drying and Storage Facts

At what moisture content can I store corn?

With aeration so the corn can be kept cool, it can be stored through the winter at moisture contents up to 23%.

Without aeration, it is risky to store it for more than a few days. Wet grain through respiration and microbial activity produces heat, so the corn may not stay cool even if placed into storage at cold temperatures. The corn temperature should monitored and be prepared to move it if temperatures increase. The allowable storage time for corn at 20% moisture is about 90 days at 40 degrees, but is only 14 days at 70 degrees.

Corn at moisture contents of 24% or greater may freeze together and not flow out of a bin at temperatures below freezing. Also, the kernel may deform restricting it from flowing.

Aeration needs to be provided to cool corn that is piled on the ground. Wind driven air will go over the pile rather than through the corn. A one inch rain will increase the moisture content of the top foot of corn by about 9 percentage points. This will likely lead to spoiled grain unless it is very cold outside and the corn is rapidly dried.

There will be more heat loss around the perimeter of a grain bag than from a bin, but if that heat loss does not keep the corn cool it will need to be unloaded. Grain bags do not prevent spoilage or grain deterioration. Corn at moisture contents above about 26% will ensile making it fit only for livestock feed. Corn at moisture contents under 22% should be okay as long as the corn temperature remains near or below 30 degrees. At moisture contents of 22% to 25%, it is critical to monitor the corn temperature until it is dried. Grain bags should be considered as temporary storage unless the corn moisture is at 14% or less.

Will corn dry in the field?

The rate of drying in the field will be extremely slow – likely only about one percentage point per week during November in North Dakota.

Can corn be air dried in November?

Natural air (air) drying is inefficient at temperatures below about 40 degrees. It takes about 70 days to dry corn from 21% to 16% during November with an airflow rate of 1.0 cubic feet per minute per bushel (cfm/bu). Adding enough heat to warm the air 10 degrees only reduces the drying time to about 50 days and will approximately double drying cost. It is best to cool the corn to 20 to 30 degrees, store it over winter and dry it in the spring.

Will a moisture meter accurately measure the moisture content of corn that is at 30 degrees?

Moisture meters will generally not give accurate readings for kernel temperatures below about 40 degrees. To get an accurate reading, place the grain sample in a sealed container and allow it to warm to room temperature before taking the measurement. The adjustment may be several percentage points for grain that is not near room temperature (75 degrees).

For more information go to: http://www.ag.ndsu.edu/graindrying

Source: Kenneth Hellevang, Ph.D., PE, North Dakota State University Extension Service Engineer

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