Every year as harvest begins and the late summer season changes into fall, this question arises: Does corn lose drymatter in the grain after it reaches physiological maturity? That is, when a "black layer" forms in the kernel tip?
"The answer is no," says Iowa State University Extension corn agronomist Roger Elmore. He points out that Iowa's corn this year reached dent (R5) development stage on pace with that of 2010, but well ahead of normal (see NASS report). Some combines are already rolling across Iowa's 14 million plus acres of corn; others will roll soon. Harvest 2011 has begun and fall is approaching.
Several years ago, 1995 to be exact, widely circulated reports in the popular farm press suggested that corn dry matter decreases after R6 (physiological maturity) during drydown. That work was never published in scientific literature.
"A colleague and I in Nebraska compared several hybrids in three years with different drying environments each year and with different harvesting techniques," says Elmore. "Grain weights, i.e. dry matter, were stable in all environments following maturity. It was clear: grain does not lose drymatter during in-field drydown." For more information on this, read the extension publication, "Corn grain yield and kernel weight stability after black layer," which is referenced below.
As grain dries in fields after the corn reaches black layer stage, you should monitor individual fields and corn hybrids for grain moisture, stalk quality and ear retention, advises Elmore. "You can lose yield to ear drop and kernels shelled out onto the soil during harvest," he adds. "That's why you should schedule your harvest of various fields, based on these variables."
Reference: Regarding drymatter stability: "Corn grain yield and kernel weight stability after black layer" is on ISU corn web page.
Additional related references:
Harvest update "It's that time again" (2011 Charles Hurburgh)
Harvest tips for lodged corn (2011, Mark Hanna)In-field drydown rates and harvest (2010, Elmore and Abendroth)