Drying down corn
Under very warm, dry conditions, corn may lose up to one point of moisture per day. But by early October, average daily temperatures in the region are in the low 50-degree-F range, resulting in a drydown rate of about 0.2-0.3 percentage points per day.
Drydown will be faster at any temperature with low relative humidity, sunshine and higher winds. The later corn reaches physiological maturity, the slower it will dry down.
Corn that matures earlier typically dries faster due to more favorable drying conditions earlier in the harvest season. Later-maturing corn has fewer warm days to aid drying and will dry more slowly.
In a typical year, corn that matured on Sept. 15 may require only 10 to 15 days to reach 20% moisture, while corn that matured on Sept. 25 may need 30 days to reach the same moisture level. This was documented by University of Minnesota research.
Hybrid characteristics that influence the rate of grain drying become more important when weather conditions are not favorable for drydown. Researchers have identified the following traits or characteristics as ones most likely to increase grain drying in the field:
• Fewer husk leaves
• Thinner husk leaves
• Quicker husk leaf death
• Less husk coverage of the ear
• Looser husks
• Quicker ear declination. The sooner the ears drop from an upright position after grain maturation to a downward position, the more rapid the grain moisture loss. In particular, husks of upright ears can “capture” rainfall.
• Thinner kernel pericarp characteristics. The pericarp is the outermost layer of a corn kernel.
• Corn hybrid, relative maturity and weather influence corn grain drydown.
• Start harvesting when corn moisture is between 22% and 25%.
• Harvesting corn below 18% moisture can result in greater harvest losses.
Ideal harvest moisture
The ideal harvest moisture for corn is between 22%-25%. Waiting for corn to dry to 18% moisture in the field saves on the energy bill, but it also increases the likelihood of excess harvest losses due to stalk lodging, ear drop and detrimental weather, all of which can affect your bottom line. Also, because many fields were planted late this year, there may not be enough heat units left this fall for in-field drydown.
Artificial drying costs will vary this season depending on LP gas prices. Nonetheless, harvesting at a higher moisture level this year may increase grower profitability, specifically when growers anticipate medium to high harvest losses. The accompanying table was developed by Iowa State University, and customized by DuPont Pioneer agronomists, to illustrate different drying scenarios and costs, based on an average LP price of $1.35/gallon.
Zach Fore is a field agronomist for DuPont Pioneer. He covers northeast North Dakota and northwestern Minnesota. Contact him at firstname.lastname@example.org. Follow local DuPont Pioneer agronomists on Twitter @PioneerSDakota and @PioneerNDakota.
This article published in the October, 2014 edition of DAKOTA FARMER.
All rights reserved. Copyright Farm Progress Cos. 2014.