Corn Drydown in the Field

The cool, cloudy and wet weather has not helped with drydown of corn in Kentucky. We have been fielding (pun intended) many questions about how much longer to let the corn stand versus getting it out of the field.

An excellent article, Field Drydown of Mature Corn Grain was just updated on this very subject by Bob Nielsen at Purdue.

Dr. Nielsen says:

"Simply put, warmer temperatures and lower humidity encourage rapid field drying of corn grain."

Also:"Average daily drydown rates will range from about 0.8 percentage point per day for grain that nears maturity in late August to about 0.4 percentage point per day for grain that nears maturity in mid- to late September... "

If the weather is cool, cloudy and/or wet, there may be very little to no drydown. So, in a normal year, you might expect corn grain to dry down by 5.6 percentage points in a week. For this season, with the current weather, expecting corn to dry down by 2 percentage points in one week could be optomistic. For what it's worth, the 10-day forecast for much of Kentucky calls for rain in four of ten days.

If corn has reached 25% grain moisture, the risks with leaving corn in the field with the current weather conditions are: 1) increased chances for sprouting in the ear, 2) increased chances for Diplodia, etc. to spread on infected ears, 3) increased chances for ear loss from wind, 4) increased chances for lodging, and 5) increased chances for another rainstorm to come in and do more damage.

The negatives of harvesting corn grain wet (between 25 and 16%) are: 1) increased demand and wear on drying equipment, 2) increased drying costs, 3) increased dockage if sold directly off the farm, 4) increased weight per bushel of grain for hauling (i.e. more hauling costs), and 5) increased chance for spoilage if dryers are not working properly.

In addition to these negatives, soil compaction is at a greater risk in some of these fields. Soil is most susceptible to compaction when the soil is just a little too wet to plant (ie. just below field capacity). Conditions favorable for field-drying of corn are also favorable for drying soil.

If we knew exactly what the weather forecast was for the next two weeks, we all could make some really smart decisions. Aside from an accurate weather forecast, I would suggest trying to get into fields between the wet weather. If possible, target fields that are drier and/or fields at greater risk for lodging. Also, if you haven't done so already, make sure your drying equipment is working at its best.

We have some very large yields currently in the fields across the state. Hopefully, we can get most of that into the bins.