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College of Food, Agricultural, and Environmental Sciences


Tips to Get Corn Off to a Good Start

April 17, 2008

COLUMBUS, Ohio -- Planting mismanagement can put a ceiling on yield potential, even before the plant emerges from the soil. Farmers should keep this in mind as they prepare for this year's corn production.

Spring started off much like last year: cool and wet. Meteorologists are forecasting warmer, drier weather for the remainder of the month, and should make for ideal planting conditions.

"For some, this year seems like a repeat of 2007, with wet weather in some areas and some cool days," said Peter Thomison, an Ohio State University Extension agronomist. "But there is still plenty of time to get the corn crop established. We don't want farmers to cut corners and push to get the corn in the ground before the field is ready. Mistakes made during the planting operation, like 'mudding seed in', are usually irreversible when it comes to impacts on yields."

But agronomists don't want growers to wait, either. The longer a grower waits to plant, the more a ceiling is put on yields.

"Generally we start seeing yields begin to fall about 1.5 bushels per acre per day of delayed planting after mid-May," said Thomison, who also holds a research appointment with the Ohio Agricultural Research and Development Center. "The record yields of recent years owe much to timely planting, as well as good seedbed conditions."

Optimum planting dates for Ohio are April 10-May 10 for southern counties and April 15-May 10 for northern counties.

"We can usually get through from May 10 to May 15 without significant reductions in yield," said Thomison.

Thomison offers the following recommendations to help growers get their corn off to a good start:

• Complete planting by mid-May. "Begin planting as soon as field conditions will allow, but avoid early planting on poorly drained soils or those prone to ponding," said Thomison.

• Adjust seeding depth according to soil conditions. "Plant between 1.5 to 2 inches deep to provide for frost protection and adequate root development. In April, when the soil is usually moist and evaporation rate is low, seed should be planted no deeper than 1.5 inches," said Thomison. "When soils are warm and dry, corn may be seeded more deeply up to 2 inches on non-crusting soils."

• Adjust seeding rates on a field-by-field basis. "Planting depths can vary from one field to another and within the same field. Adjust seeding based on soil type and drainage characteristics," said Thomison. Lower seeding rates are preferable when droughty soils or late planting (after June 1) limit yield potential. On soils that average 120 bushels per acre or less, final stands of 20,000 to 22,000 plants per acre may be adequate for optimal yields. On soils that average about 140-150 bushels per acre, a final stand of 28,000 plants per acre may be needed to optimize yields. On soils averaging 175 bushels per acre or more, final stands of 30,000 plants per acre or higher may be needed to optimize yields.

Plant full-season hybrids first, followed by mid-season and short-season hybrids. "Full-season hybrids lose the most yield potential the longer a farmer waits to plant them," said Thomison.

Growers could still be dealing with delayed planting if rains move in or soils are slow to dry.

"If we get into a pattern of wet weather every week between now and the start of planting, we might be in trouble. But even then, we can plant a lot of corn quickly during times of ideal planting conditions," said Thomison. "Based on previous years, corn growers can plant as much as 40 percent to 50 percent of the state's crop in a single week given good working conditions."

For more updates on corn production, refer to the OSU Extension Agronomy Team Web site at

Candace Pollock
Peter Thomison