Corn Tips for November 2004
By Ken Hellevang, Post Harvest and Structures Engineering Specialist
NDSU Extension Service

An article by Joe Lauer, University of Wisconsin corn agronomist, provides information on what happens when corn is left in the field over winter. For the years 2000 and 2001, the field loss ranged between 18 percent and 65 percent. The average corn moisture, based on data from 1992, 1993, 1994, 2000 and 2001, was about 27 percent in November. It stayed at 22 percent during December and January, then gradually dried to about 20 percent in February, 18 percent in March and 15 percent in April.

 

In 2002, there was a great deal of corn in the field in the Devils Lake area at moisture levels in the upper 20 percent range at the beginning of November. By the end of November, the corn had dried to the lower 20 percent range. This would be about 5 percentage points in 30 days or about 0.15 percent per day. Based on the literature, little drying may be expected during November because the air is too cold to remove moisture rapidly.

 

Based on average North Dakota temperatures and relative humidity, the equilibrium moisture content (EMC) of corn is 19 percent to 20 percent during November through March. Normally, corn will gradually dry to about 20 percent during the winter. The EMC for corn during average.

 

April conditions is about 16 percent and for May is about 14 percent.

 

Natural air and low-temperature drying with an airflow rate of at least 1 cubic foot of air per minute per bushel would be an option for spring drying of corn harvested at 21 percent moisture or less. The drying fan should be started in the spring when average temperatures rise above 40 degrees.

 

Moisture meters will not give accurate readings for corn kernel temperatures below 40 degrees. To get an accurate reading, place the corn sample in a sealed container and allow it to warm to room temperature before taking the measurement. In addition, it is important to remember to make a temperature adjustment to the meter reading for kernel temperatures above 40 degrees. The adjustment may be 2.5 percent for corn near 40 degrees.  Read and follow the operator’s manual to obtain accurate readings.

 

Snow is an excellent insulator. If snow covers a cornfield before the ground is frozen, the ground may not freeze very deep.  The average snowfall during the winter in Fargo is about 39 inches, with a water equivalent of 3.9 inches.  The effect of this snowfall on spring field conditions must be considered as producers make their decision.  

Costs for high-temperature drying consist of primarily the propane and the capital or fixed cost. The estimated cost of propane is about 0.022 multiplied by the propane price per-gallon. For a cross-flow column dryer, the expected propane cost is about $0.025 per point of moisture per bushel for $1.10 propane, and $0.029 for $1.30 propane. The estimated cost of propane to dry corn from 25 percent to 15 percent using $1.30 propane would be 10 multiplied by $0.029, which equals 29 cents. The capital and fixed cost might be about 15 cents per bushel, so the total cost is 29 cents plus 15 cents or 34 cents per bushel.  The estimated time to dry in a high-temperature dryer is about 10 to15 minutes per point of moisture.  

 

Test weight increase during drying in a high-temperature dryer is normally about 0.25 pounds per point of moisture. The increase is dependent on the amount of mechanical damage, dryer design and dryer temperature. The increase this year will probably be less than the quarter-pound per point.

More information, including a presentation on corn and soybean drying and storage, is available at  www.ag.ndsu.nodak.edu/abeng/postharvest.htm