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Harvesting late-season corn

Greg Blonde
UW-Extension Agriculture Agent
It’s generally recommend that harvesting corn for dry grain storage should begin at about 24-25 percent kernel moisture.

WAUPACA COUNTY - According to Joe Lauer, Extension Corn Agronomist at UW-Madison, by late October to early November, field dry down rates usually drop to 1/4-1/2 percent per day, and by mid November, less than a 1/4 percent per day. By late November, drying rates will be negligible, if any drying occurs at all.

So what are the options for dealing with wet corn?

It’s generally recommend that harvesting corn for dry grain storage should begin at about 24-25 percent kernel moisture. Allowing corn to field dry below 20 percent brings greater losses from stalk lodging, ear rots and wildlife damage. Be prepared for localized root lodging and stalk lodging that may slow harvest and contribute to yield losses.

Here are recommended harvest options at different moisture levels:

  • 33-35% (plant) = Silage harvest
  • 29-32% (kernel) = High moisture morn ensiled
  • 25-26% (kernel) = Ideal for combining
  • 20-23% (kernel) = Ideal for picking
  • < 20% (kernel) = Higher field losses, lower drying cost

To assess lodging potential use either the pinch test or the push test to check for stalk integrity. Conduct the pinch test by squeezing the second or third internode above the ground. If it collapses, stalk quality is compromised.

The push test is performed by pushing a corn stalk to approximately 45 degree angle. If it breaks, stalk quality has been reduced. If 10 percent of the stalks tested show poor stalk quality or lodge at the root, then these fields should be harvested earlier.

To determine pre– and post-harvest ear loss, keep in mind one 3/4 pound ear in each 1/100 of an acre equals one bushel per acre loss (1/2 pound ear equals 2/3 bushel yield loss).

To determine 1/100 of an acre, take the normal 1/1,000 acre distance and multiply by 10. In 30" rows, 1/1000 of an acre is 17' 5", so 1/100 acre equals that distance across 10 rows.

For each ear in that area, there is one bushel per acre loss. Behind the combine, every two kernels per square foot on the ground equals one bushel per acre of machine loss. Typical harvest loss will range from 0.5 to 2.5 bushels per acre. 

A two year study of field losses of corn left standing after October reported 3-5 percent loss in November, 22 percent in December and if the corn is allowed to stand in the field all winter, a loss of up to 40 percent.

Balancing drying cost with time to finish harvesting, crop condition (lodging) and increased combine losses and lower corn prices makes the decision to delay corn harvest this fall especially tough.

Keep in mind it takes about 0.02 gallons of propane to remove one point of moisture from a bushel of corn, so to estimate drying costs for a high temperature dryer, multiply propane price by 0.02 and then multiply by the number of percentage points of moisture to be removed (ie. $1.25/gal propane with corn to be dried from 28 to 15 percent (13 points = $1.25 x 0.02 x 13 = $0.33 drying cost per bushel). 

And don’t forget, safety is no accident, especially during a late season harvest.

Pricing standing corn

To evaluate options for standing corn, check out this smart phone app released in 2014.

The app is free and available for Android smart phones and tablets on the Google Play store by searching for “HMSC” or go to:

Farmers can use this app to help determine an equivalent value for wet shell corn when compared with a dry shell corn price (a link to current local elevator dry grain bid prices is also built into the app).

The equivalent wet price is then calculated and displayed in both price per ton and price per bushel. Additional drying cost (propane or electric) can also be evaluated under the “expense” tab. Results can then be emailed from your phone to your computer, and/or emailed directly to others.