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With recent above-normal temperatures, drying corn in the mid-20% moisture range should be expected.

September 30, 2019

3 Min Read
grain bins with dead corn field in foreground
OPTIMUM CAPACITY: Using the maximum drying temperature that will not damage corn increases dryer capacity and reduces energy consumption per point of moisture removed.Tyler Harris

By Ken Hellevang

Each year brings challenges for corn production. However, even with this year's late planting, corn harvest appears to be fairly typical.

According to USDA's National Agricultural Statistics Service, corn dented was near average, but only 19% was mature Sept. 15, behind the 35% average. These are average conditions, so it is important to check the maturity level in each field. With warm weather, corn maturity before frost in early October should be expected for corn that is nearing maturity.

The National Oceanic and Atmospheric Administration's forecast is for above-normal temperatures and near-normal precipitation for October. Above-normal temperatures are forecasted for November, with above-normal precipitation possible.

Field drydown typically is about 0.3% to 0.5% points per day in October, but much less than that in November because of the cooler and shorter days. Corn at maturity has a moisture content of about 35%.

If corn reaches maturity Oct. 5, it may be expected to have a moisture content of about 22% to 25% by the first of November. Drying corn at moisture contents in the mid-20% range should be anticipated.

Corn above 21% moisture should not be dried using natural-air or low-temperature drying to minimize corn spoilage during drying. Because the drying capacity of NA and LT is extremely poor at temperatures below 35 to 40 degrees F, little drying typically is possible using a natural-air system after about Dec. 1 in Nebraska.

Adding heat does not permit drying wetter corn and only slightly increases drying speed. The primary effect of adding heat is to reduce the final corn moisture content.

When outdoor temperatures average near or below freezing, cool the corn to 20 to 25 degrees for winter storage and finish drying in March to early April. Limit the corn depth to about 20 to 22 feet to obtain an airflow rate of at least 1.0 cubic feet per minute per bushel, which is necessary to dry the corn before deterioration occurs. Turn fans off during extended periods of rain, snow or fog to minimize the amount of moisture the fans pull into the bin.

Using the maximum drying temperature that will not damage the corn increases the dryer capacity and reduces energy consumption per point of moisture removed in a high-temperature dryer.

Removing a pound of water requires about 20% less energy at a drying air temperature of 200 degrees than at 150 degrees. Follow the dryer manufacturer's recommendations, but generally, recommended temperatures when drying corn are 210 to 230 degrees.

Be aware that excessively high drying temperatures may result in a lower final test weight and increased breakage susceptibility. A cross-flow dryer that moves corn from the inside to the outside of the drying column, varies the corn flow rate across the drying column, or varies the corn's exposure to the drying air is more likely to maintain corn quality.

Removing debris that accumulates on or in a dryer is more critical when outside air temperatures are cold because condensation can develop on the dryer, creating a wet surface on which debris can collect. The debris may reduce airflow through the dryer, decreasing the dryer's capacity and creating a fire hazard.

Cool the grain in storage to about 20 to 25 degrees for winter storage in northern corn-growing regions and near freezing in warmer regions.

For information, visit NDSU's grain drying page at ag.ndsu.edu/graindrying.

Hellevang is a North Dakota State University Extension engineer.

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