sealPurdue News

May 1996

Drydown reduces corn yield, Purdue study finds

NOTE TO JOURNALISTS: Complete information about this study can be found on the World Wide Web at

WEST LAFAYETTE, Ind. -- Some farmers and seed industry representatives say that corn loses valuable grain weight, or yield, if left to dry down in the field after it matures -- a concept that has been scoffed at by many experts.

Based on what Purdue corn specialist Bob Nielsen found out in a four-year study, the farmers and seed reps are probably right.

Nielsen and three graduate research assistants tested three hybrids (Pioneer brands 3527, 3394 and 3245). In three of the four years, all three hybrids lost kernel dry weight during in-field drydown following maturity.

The study's exceptional year was 1993, when no significant changes in kernel dry weight were observed for any of the three hybrids.

According to Nielsen, the bottom line is that in-field drydown could mean a loss on a farmer's bottom line.

"Our data suggest that the potential rate of yield loss averages 1 percent per point decrease in grain moisture content; so, if mature grain were allowed to dry down 10 percentage points -- from 28 percent to 18 percent grain moisture content -- the potential yield loss would be 10 percent," he says.

By doing some extra computations, Nielsen has extrapolated from this data that the optimum grain-moisture content for harvest is near 25 percent -- which agrees with the long-held notion about what constitutes optimum harvest moisture levels.

"Harvesting grain at moistures much greater than 25 percent often damages kernels, while harvesting at lower moistures can often cause greater mechanical harvest losses such as ear droppage and kernel shattering," he says.

More information about corn production can be found on the World Wide Web at

CONTACT: Nielsen, (765) 494-4802; Internet,
Purdue News Service: (765) 494-2096; e-mail,

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