Study: Maximum Grain Yield for Indiana Cornfields Occurs at 32,000 Plants per Acre

Many of John Deere's planters include variable-rate seeding technology to improve efficiency on the field.
Many of John Deere's planters include variable-rate seeding technology to improve efficiency on the field.

Purdue Extension Corn Specialist Bob Nielsen says that Indiana corn farmers may raise a record number of plants per acre this year, primarily due to new seeding technology and hardier hybrids.

Nielsen and his colleagues analyzed the results of 67 field-scale trials, which have been conducted throughout Indiana since 2008. They were able to determine that the maximum grain yield for a typical Indiana cornfield under normal growing conditions occurs at a population of 32,000 plants per acre.

Corn plant populations have steadily increased in the state over the past 25 years by approximately 200 plants per acre. Nielsen believes that this is primarily due to the improved stress tolerance of plants. However, he also notes that variable-rate seeding equipment, which has become a standard on most corn farms, is allowing farmers to put down different rates of seed in various areas of their fields.

In order to achieve the “ideal” plant population of 32,000, Nielsen says that farmers should put down between 32,500 and 34,300 seeds per acre.

“Growers should routinely calibrate the seed drop of their planters, count established plants no earlier than V6 (six visible leaf collars), and calculate percent stand in all their fields every year to determine whether there is room for improvement,” Nielsen wrote in his report, Yield Response of Corn to Plant Population in Indiana. “With today’s planter technologies and seed quality, aiming for a percent stand of no less than 95 percent is certainly achievable. Equally important is that the knowledge of your historical percent stand allows you to convert recommended final plant populations to seeding rates.”

As seeding technology and hardier hybrids continue to emerge, corn farmers will likely continue to drive plants per acre to greater heights.