Determining When to Harvest Your Dry Corn

“I have Lancaster Field Corn, Blue Dent Corn, and Bloody Butcher Corn.  What percentage moisture should the ears be at harvest?  Thanks, ~H.”


Depending on the variety and seasonal conditions, minimum kernel damage occurs between 19 and 24 percent moisture (% m.c.). In some cases, damaged corn has been discounted as foreign material or dockage.

Preharvest and gathering loss vary with insect damage, lodging, and how tightly ears are held. Ear droppage begins in the twenties (% m.c.) and accelerates as corn dries. Storms come without much warning; therefore, verify if stalk rot or insect damage exists. If lodging risk is high, harvest early (around 20% m.c.) to avoid a potential 10- to 20-bushel per acre field loss.

Rice harvest may also conflict with corn harvest. It may be desirable to harvest corn at 18 to 24 percent moisture to allow time to clean and empty equipment before handling rice. In most cases this requires farm drying so allow sufficient time to dry the corn properly. If rice and corn production schedules aren’t planned, inadequate drying or grain storage prevents timely harvest. Corn field drying rates vary from ½ to 1 percent moisture content loss per day. Starting harvest at 24 percent instead of 18 percent moisture may get the combine into the field 6 to 12 days earlier.

Aflatoxin isn’t likely to be a problem in well-managed corn. However, aflatoxin proliferates so rapidly in Midsouth fields that a grower should consider his options. If corn can be dried to 15 percent or below within a day, the spread of aflatoxin is minimized by early corn harvest. Corn as wet as 28 percent moisture can be harvested by adjusting the combine for reduced kernel damage and improved separation.

Drying costs or high-moisture market discounts cause some to wait too long to harvest corn. Corn that remains in the field too long suffers weight shrinkage, damage and field loss. Gathering loss increases as corn moisture falls below 20 percent; field loss may be above 5 bushels per acre.

Economical harvest timing depends on the drying cost or high-moisture discounts and field loss and damage penalty. Look at your circumstances, including the risk of field loss, how quickly all of your corn can be harvested, your drying options, and market. Recover most of the drying cost by reducing field loss and kernel damage. On this basis, beginning corn harvest at 20 percent m.c. is a sound decision for some; starting harvest around 18 percent m.c. fits many situations. Exposure to weather risks, shrinkage, field loss, and damage are compelling reasons to complete all corn harvest before it reaches 14 percent m.c.



© Mertie Mae Botanics LLC and Horticulture Talk!, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Mertie Mae Botanics LLC and Horticulture Talk! with appropriate and specific direction to the original content.


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