Now that a killing frost has occurred, most corn in the field in the Dakotas will a have test weight of about 56 pounds per bushel and a moisture content of about 30%, says Ken Hellevang, North Dakota State University Extension ag engineering and grain drying specialist.
“It is important to check each field because these values will vary depending on planting date, corn maturity rating and growing degree days during the year,” Hellevang says.
Standing corn in the field may dry about 2.5 percentage points per week in North Dakota during October, assuming normal weather conditions, and about 1 percentage point per week during November.
Corn at 35% moisture content on Oct. 11 might be expected to dry to about 27% by Nov. 1 and about 22% by Dec. 1, Hellevang says
The Oct. 14-18 temperature is predicted to be much below normal across the Corn Belt, with a tendency for above-normal precipitation for Oct. 16-22.
“If these forecasts are accurate, the amount of field drying will be reduced,” Hellevang cautions.
Field drying normally is more economical until mid to late October in North Dakota, and mechanical high-temperature drying normally is more economical after that, Hellevang notes.
Field drying is extremely slow during winter, and corn will dry only to about 20% moisture content based on the equilibrium moisture content for average monthly air temperature and relative humidity conditions in North Dakota. Corn that remains in the field during the winter may dry from 25% to 30% moisture in November to 17% to 20% when harvested in February and early March.
Corn losses will depend on stalk strength, ear shank attachment to the stalk, winter conditions and wildlife. Accumulated winter snow adds water to the soil as it melts. Plus, standing corn shades the ground, which reduces drying and may lead to wet fields in the spring, so consider harvesting the corn before the ground thaws, Hellevang says.
Natural-air and low-temperature drying are limited to initial corn moisture contents of about 21%. Even at that moisture content, air drying is limited in the Northern states due to the colder outdoor temperatures in late October and November.
The moisture-holding capacity of air is very small at temperatures below roughly 40 degrees F. Expect to store the wet corn for the winter by cooling it to 20 to 30 degrees and finishing the drying in the spring when the outside temperatures average above 40 degrees.
Provide an airflow rate of at least 1 cubic foot per minute per bushel to complete the drying before corn deterioration affects the market quality. The required fan size to provide the needed airflow can be determined using a fan selection program. Do an internet search for NDSU grain drying and storage to access a fan program.
High-temperature corn drying may face challenges with high-moisture corn, Hellevang says. The kernel color of immature corn may be affected during drying due to sugars still being in the kernel. Reduce the dryer temperature to reduce the potential for affecting the kernel.
Hellevang also warns that corn at moisture contents above about 23% may have enough surface moisture on the kernels that the kernels freeze together and will not flow.