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College of Food, Agricultural, and Environmental Sciences


Ohio Farmers Planting More Corn Per Acre

April 7, 2011

COLUMBUS, Ohio -- Today's generation of corn hybrids can withstand more stress -- and therefore more crowding -- than farmers have ever seen. And that means farmers often can plant more seeds per acre and have a good expectation of high yields, at least up to a point, says an Ohio State University Extension agronomist.

"Just 10 years ago in Ohio, we were looking at final stands of about 24,000 plants per acre," said Peter Thomison, corn specialist for OSU Extension. "There's been a steady trend toward higher plant populations. Now, many Ohio farmers are planting more than 30,000 seeds per acre, and seed companies are asking us to test up to 42-50,000 plants per acre -- if only to see how the plants handle the stress."

Genetic improvements in hybrids have bettered corn in a number of ways, including stabilizing yields across a range of environmental conditions; increasing plants' tolerance to drought and higher plant populations; enhancing stalk and root strength; and increasing resistance to disease and insects.

Since 2006, Thomison, who also holds an appointment with the Ohio Agricultural Research and Development Center, and colleagues have tested how corn responds to various planting densities across a range of environments. At nine locations throughout Ohio, they have tested fields with final stands of 24,000, 30,000, 36,000 and 42,000 plants per acre. In three of those years -- 2006, 2009 and 2010 -- they found optimum yields when seeding at rates of 36,000 and above. However, in 2007 and 2008, the corn didn't respond as well to higher seeding rates; 30,000 plants per acre provided the best yields.

"In 2008, high winds associated with Hurricane Ike caused excessive lodging in the fields, and the worst lodging was in the test plots with 42,000 plants per acre -- lodging averaged 52 percent in those plots," Thomison said. "In 2007, there was no similar event, but we still didn't see a yield response above 30,000 plants per acre."

In 2010, plant populations for corn in Ohio averaged 28,200 plants per acre -- representing an increase of 16 percent since 2000, and of 56 percent since the 1970s. But it's still lower than most other Corn Belt states -- 29,900 plants per acre in Minnesota; 29,950 in Iowa; 29,650 in Illinois; and 28,350 in Indiana.

Based on his research to date, Thomison recommends a seeding rate of 31,000 to 33,000 seeds per acre for most Ohio fields planted in late April and early May. For fields that normally have a low yield potential, rates of 24,000 to 26,000 seeds per acre would probably be sufficient, he said.

Thomison emphasizes that farmers will want to examine the costs and possible income from potentially higher yields associated with greater seeding rates before making a decision. Although seed companies offer some good discounts and incentives, substantially increasing planting density could require a substantial up-front investment. Still, he adds, reducing seeding rates just to lower seed costs usually costs more than it saves.

Farmers also may consider varying seeding rates depending on the yield potential of different parts of a field, he said.

"You might want to push populations in well-drained fields with higher organic matter that have generated consistently high yields in past years, and plant fewer kernels per acre on higher ground, or clay knolls. The decision really has to be dictated by the yield history of specific fields."

Thomison also recommends talking to seed company representatives for additional guidance for specific hybrids, especially with regard to the risk of greater stalk lodging associated with higher seeding rates. "They know the specific traits and genetic background of their seed, so talk to them about your plans."

Martha Filipic
Peter Thomison