John Pocock 1

March 18, 2011

5 Min Read

With wet, and/or snow-covered soils predominating from Missouri to Minnesota well beyond mid-March this year, Midwestern farmers are understandably anxious about the odds for timely corn planting. However, the best advice to corn growers for now is preparation and patience, according to Jeff Coulter, University of Minnesota, and Bill Wiebold, University of Missouri, Extension corn agronomists.

“The main thing is to be organized and prepared so that when soils are fit and it’s time to roll, you’ll be as efficient as possible with whatever planting window you’re given,” says Coulter. “So, make sure to have your logistics in place, your machinery calibrated and your labor lined up before fieldwork begins, and don’t be in such a hurry to get started that you harm your seedbed.”

Be both prepared and patient, agrees Wiebold. “If you try to plant when soils are too wet, you can cause more damage to your crop than what you might gain by planting at the right date for maximum yields,” he says. “The consequences of planting too wet will not only include uneven stands and emergence issues – it will also diminish the crop’s ability to take up moisture and nutrients and then to yield well if the weather turns dry during summer.”

To help guide farmers for a potentially challenging, cold and wet spring planting season, Wiebold and Coulter provide the following five tips:

1. Ensure soils are fit for fieldwork. “Be patient with field cultivation ahead of planting,” says Coulter. “If you do your pre-plant tillage before the soil is dry enough, you could end up with a cloddy seed bed and poor stands. Planting before soils are fit can also cause significant problems, such as sidewall compaction, which restricts root growth and nutrient uptake, and seed furrows that don’t close adequately, resulting in poor seed-to-soil contact and uneven emergence.”

Be cautious and don’t damage your soils, advises Wiebold. “Here in Missouri, our farmers would likely cause more damage when planting too wet during the optimal planting-date-window than by waiting five days when the soils are drier.”

2. Be unflappable with planting-date delays. The optimal planting dates for central and northern Missiouri typically occur from about April 10 to 25 and about two weeks earlier than that in the southern parts of the state, says Wiebold. Still, “regardless of your latitude, the loss of yield is fairly small if planting the first week to 10 days after what is considered the optimal planting window,” he adds.

 Minnesota’s Coulter concurs. “On average, the planting-date window from April 21 to May 6 will put a corn crop in Minnesota within 1% of the maximum yield potential,” he says. “However, only about a 3% yield reduction occurs here when planting is delayed until mid-May.”

3. Apply a pre-emergence herbicide with residual control. In a cold and wet spring, rainfall after planting on already wet soils can make it difficult for farmers to move machinery into fields for timely postemergent applications and weed control, points out Coulter. The residual chemistry from pre-emergence herbicides will give farmers some early weed control and allow for a wider window to apply postemergence herbicides, he adds.

In Missouri, using a pre-emergence herbicide is an important tool in the fight against herbicide resistant weeds, no matter what the conditions at planting time, notes Wiebold. However, in a wet spring, “weeds can really get away from you pretty quickly if you’re so focused on planting that you aren’t able to also apply herbicides in a timely manner,” he says. “So, don’t get too hung up on timely planting that you don’t also get your herbicide down and your nitrogen (N) on, too.”

4. Consider a boost in seeding rates. “If it looks like another cold, wet spring, it might be wise to bump up your seeding rates a bit, especially in a corn-on-corn or high-residue situation,” says Coulter. “This will compensate for the lower emergence than what normally occurs in an ideal soil situation. Also, if significant rainfall occurs after planting on soils that are already abundant in moisture, there is increased potential for N loss, so monitor the crop’s N status and be ready to sidedress N, if it becomes necessary later in the season.”

Farmers planting into a stressed environment for growing corn should probably increase their seeding rate somewhat, agrees Wiebold. “However, when making a decision to increase your seeding rate, first know what your final target stand is for each field, and then make a boost in rate based on that field’s potential vulnerability to stress,” he says. “Increasing your seeding rate may be more appropriate for stress-vulnerable, clay-pan soils in the northern and central parts of Missouri, compared to the deep, well-draining fertile soils in the Missouri Bootheel area.”

5. Remove residue from the seed zone. “It is critical to use row cleaners at planting to move residue off the row to help soils warm up more quickly and enhance growth,” notes Coulter. “Also, be careful to avoid the temptation to plant shallow when soils are cooler and wetter than normal. Shallow planting increases the risk of poor nodal root establishment, which could reduce yields and increase the potential for lodging.”

Removing residue over the row can provide a benefit to help soils dry out sooner, but the same practice could also pose a soil conservation risk in certain situations, says Wiebold. “In general, for the southern Midwest it’s not as critical as it is in the northern Midwest to move that residue off the seed zone to warm up soils,” he says.


Another worry farmers may have during a late spring-planting season is when to make a switch from a full-maturity hybrid to an early maturing variety. However, Wiebold cautions against such a switch, unless corn planting becomes delayed well past the optimal planting-date window, due to the yield loss that will likely occur. He adds that switching from corn to a different crop when weather delays timely planting also seldom makes sense.

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