Ask an Agronomist
How Late Can I Leave Corn in the Field to Dry Down?
Sep 27, 2011
Question: How late can I leave corn in the field to dry before I harvest it?
Farmers should think twice before expecting Mother Nature to pay the cost of drying corn by leaving it in the field longer this harvest, says Ohio State University Extension corn expert Peter Thomison.
"We don't encourage growers to leave corn in the field much past early November, because after that there is really very little moisture loss in corn," he said. "Sometimes people think the corn will continue to dry, but typically moisture stays pretty much stable after mid-November."
Thomison said that in typical years, when corn is planted at normal dates between mid-April and late May, the crop follows the general pattern of drydown in the fall. That pattern includes drydown of up to a percentage point of moisture each day from physiological maturity, often called black layer, through early to mid-September when conditions are usually warm and dry.
In October, he said, that rate of drydown may drop down to half a percentage point, and then by November, a quarter of a percentage point, if it dries further at all.
"This, of course, isn't a normal year," Thomison said. "When we have these late planting seasons in Ohio, the historical effects on yields are pretty consistent, but effects on moisture are fairly mixed."
He noted that this year, because of recent rains, growers would likely harvest the corn crop in mid-October. With that in mind, those farmers should assume the corn will be of a higher moisture content coming out of the field than corn from fields planted during a more normal date range.
Thomison said there is no data to suggest that frost plays any role in helping dry corn, and that by that point in the season, corn is likely as dry in the field as it will get.
"The longer you leave the corn in the field, you start to see significant potential for stalk lodging issues," he said. "It can affect how effective your combine is at picking up corn. Farmers should start inspecting their fields pretty regularly as corn starts drying down for stalk quality, and earmarking problem fields for harvest as soon as conditions allow."
He recommended employing the pinch test to determine stalk health when scouting fields for potential stand issues. To determine if stalks are likely to lodge, he said, pinch the first internode about the brace roots, and if the stalk pinches, it is more likely to lodge.
He noted, however, that many modern hybrids are designed to withstand some of the issues that might cause lodging, and many have tougher rinds that allow them to stand up longer.
"But, later-planted corn typically is generally more susceptible to lodging issues," Thomison said. "Also, because we had corn in some areas that could have been subjected to three separate wind events that knocked plants down, that's going to be another complication this harvest."