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May 1, 2002

Crop specialist: Too wet to plant corn? Then play by the 'rules'

WEST LAFAYETTE, Ind. – Farmers frustrated with the rainy spring shouldn't let the weather cloud their thinking about corn planting decisions.

Although prime planting days are being washed away with every downpour, corn growers can adjust their tillage practices to get seed in the ground near the May 5 target date, said Tony Vyn, Purdue University Cooperative Extension Service cropping systems specialist.

Many Midwest farmers are behind in corn planting. According to the U.S. Department of Agriculture, only 4 percent of the Indiana corn crop was planted by Sunday (4/28). In comparison, 36 percent of the state's corn was planted by the same time a year ago, en route to a May 20 completion – the fastest on record.

Ohio (5 percent planted) and Illinois (25 percent planted) also are well off last year's planting pace.

As farmers ponder their planting options, they'll want to keep in mind Vyn's "Ten Tillage Rules in a Wet Spring."

At the top of the list: Use no-till systems whenever possible.

"First of all, consider doing no tillage at all if that is the fastest way to accomplish corn planting," Vyn said. "This might be the year – particularly if you're following soybean stubble – where you may be well advised to no-till plant when soil conditions at the surface are dry enough.

"Sometimes it's possible to achieve a successful no-till planting, whereas tillage on the same day might bring up clods and make it even more challenging to achieve a uniform seedbed condition that corn plants will thrive in."

A second wet spring tillage "rule" is planting in what's known as a "stale seedbed."

"Stale seedbed basically means planting without using any additional secondary tillage into a soil that was already disturbed after the harvest of the previous crop," Vyn said. "If that soil is reasonably level and not highly crusted, then there is an opportunity to take advantage of a good surface drying to plant immediately."

Vyn's remaining "Ten Tillage Rules in a Wet Spring" include:

• Use burndown and/or residual herbicides to control winter and spring annual weeds as soon as fields are dry enough to support equipment. Early weed control speeds surface drying by evaporation, eliminating the need for deeper tillage later.

• Avoid deep secondary tillage. Average tillage depths should not exceed 3 inches.

• Limit secondary tillage to one pass. The sooner planting begins, the better.

"Farmers sometimes pride themselves in having a tabletop-smooth seedbed," Vyn said. "This is not the spring to do that because of the economic costs associated with yield loss when corn is planted after the optimum date."

• Leave wet soils alone as long as possible to prevent possible soil compaction.

• Plant corn within 36 hours of any tillage. This will preserve seedbed moisture.

• Refrain from excessive in-row soil disturbance when planting. Multiple coulters per row or deeper adjustment of existing coulters and tined row cleaners will not enhance seedbeds in damp soils.

• Give no-till planting even greater consideration the longer planting is held up by weather.

"Yield reduction associated with no-till has typically been the case when corn follows corn," Vyn said. "It has been less likely when corn follows soybeans. It is decidedly less likely the later the corn planting is delayed. So as we move past early May through to mid-May and there's still corn left to be planted, one would expect less yield reduction from a well-done, no-till planting compared to conventional tillage."

• Learn more about new tillage systems that can lessen the future risk of late corn planting. Also, determine where a field may benefit from additional tile drainage.

"The spring of 2002 may be a challenging one in terms of soil moisture conditions, but it also should prompt renewed thinking about the merits of soil-conserving, cost-conserving and time-conserving tillage systems," Vyn said.

"New tillage options developed in the last decade also provide new alternatives to reduce late-planting risks on moderately and poorly drained soils. The best alternatives will vary with your soil and current field situations."

For more advice on late corn planting, read Vyn's "Tillage Options for Corn in a Wet Spring." The paper appeared in a recent issue of Purdue's Pest & Crop Newsletter. The newsletter is available online.

Writer: Steve Leer, (765) 494-8415, sleer@aes.purdue.edu

Source: Tony Vyn, (765) 496-3757, tvyn@purdue.edu

Ag Communications: (765) 494-2722; Beth Forbes, bforbes@aes.purdue.edu; http://www.agriculture.purdue.edu/AgComm/public/agnews/

Related Web site:
Purdue University Department of Agronomy Extension page
Purdue Agriculture News Hot Topics – Delayed Planting

Purdue News Service: (765) 494-2096; purduenews@purdue.edu


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