Purdue seeding trial results show more corn plants per acre


To achieve the ‘ideal’ population of 32,000 seeds per acre, farmers should put down 32,500 to 34,300 seeds per acre.

WEST LAFAYETTE, Ind. — Midwestern corn farmers could raise a record number of plants per acre in 2015, mostly due to new seeding technology and hardier hybrids.

Assessing the results of 67 field-scale trials conducted throughout Indiana since 2008, Purdue Extension corn specialist Bob Nielsen and his colleagues determined the maximum grain yield for a typical Indiana cornfield under normal growing conditions occurs at a final population of 32,000 plants per acre. Last year, the estimated average plant population statewide was about 30,850 plants per acre.

In 2012, half of the state’s corn fields had more than 30,000 plants per acre, compared with only 5 percent in 1998.

Improved stress tolerance

Corn plant populations have steadily increased in Indiana over the past 25 years by about 300 plants per acre per year. Probably the biggest reason for the increase in corn population, Nielsen said, is the improved stress tolerance of modern hybrids, meaning the plants do better in densely populated fields.

Variable rate technology

Variable-rate planter technologies are another factor. Although variable-rate seeding tools have been commercially available for years, they are now becoming standard equipment on most corn planters, Nielsen said.

Variable-rate seeding allows farmers to put down different rates of seed in different parts of their fields. The field studies included a variety of hybrids and some split-planter comparisons using pairs of hybrids purposely chosen for their advertised differences in response to population, Nielsen said.

Indiana numbers

The research team — consisting of Nielsen, Jason Lee and Jim Camberato — studied corn fields throughout the state, ranging in size from 30 to 100 acres. All of the trials were conducted on 30-inch rows. Growing conditions ranged from ideal to severe stress.

Nielsen said the results indicated that under severe stress, corn does best with a final population of 21,000 to 24,400 plants per acre. Percent stand — the number of grain bearing plants at harvest divided by the seeding rate — ranged from 79 percent to 100 percent, with an average of 96 percent. To achieve the “ideal” population of 32,000 seeds per acre, farmers should plan on putting down 32,500 to 34,300 seeds per acre, Nielsen said.

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