Early Planting Creates Added Challenges
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Early Planting Creates Added Challenges
When that soil thermometer finally crests the 40-degree mark, it’s hard for anxious farmers to keep from plunging corn planter units into chilly soil. But planting early can present challenges, from corn emergence to weed control.
While everyone knows corn begins germination when soil temperature reaches 50 to 55 degrees, farmers throughout the Corn Belt feel that race to get all their corn planted by May 10 when yield potential begins to decline. That gives farmers approximately 30 days to plant from their initial crop insurance planting date, minus rain or equipment delays or shifts to soybean planting.
“If the weather outlook is trending warmer, corn can be planted when soil temperatures hit the mid-40s,” says Jeff Coulter, University of Minnesota Extension corn agronomist. “Seed planted into low-40s soil temperatures followed by a cold rain imbibed by the seed can lead to numerous problems that inhibit emergence.”
Improved corn genetics and seed treatments have reduced some early-planting risks. Hybrids with good ratings for stressful emergence are critical for early-planted fields, as corn usually requires 90 to 120 Growing Degree Days (GDD) to emerge after planting. If adequate soil moisture and good seed-to-soil contact exist, corn emergence can take three weeks in 50- to 55-degree soil temperatures or 10 to 12 days in 60-degree soils.
Uniform Planting Depth
Another critical tip is maintaining a uniform 2-inch planting depth. Coulter says there’s less temperature fluctuation and more consistent soil moisture in this zone than shallower depths to provide more uniform emergence. “Shallower planting isn’t recommended due to inconsistencies, yet situations in bone dry soil can warrant 2.5-inch planting depth.”
Coulter says farmers should consider that early planting won’t necessarily boost yields. The yield benefit can occur on the back end for the fields planted last by ensuring they are planted around May 10. Yet, later planted fields may produce higher yields in some years if the typical higher temperatures and reduced rainfall that occur later in the season don’t stress the pollination and grain-filling periods.
Another reason farmers push earlier planting is because it enables the use of longer-season hybrids which have greater yield potential. “Farmers are seeing that we have the growing degree units to handle higher relative maturities (RM),” Coulter says. “At our Waseca, Minnesota, location (40 miles north of the Iowa border), the full season used to be 103 RM; now it’s 106 to 108 days RM. The genetics have improved, with better standability and quicker drydown.”
Weed Mindset Shift
Planting early also shifts a weed control mindset to think through a possible more significant weed problem. Deploying early scouting becomes critical to choose your least weedy fields that will reduce competition with the emerging corn crop.
Earlier planting also means corn is slower to canopy, giving weeds more opportunity to compete for water, sunlight and nutrients.
Like all corn fields, starting weed-free with a preplant/preemergence application with multiple modes of action, followed by a postemergence herbicide that includes residual activity, will help optimize yield potential. Pre-plant tillage or burndown in no-till will reduce early weed populations; watch herbicide labels for planting intervals.
“The challenge with early planting is applying your preemergence earlier, which halts residual weed control sooner. That pushes your post application earlier than normal, increasing the potential for a second post spray or more weed seeds in the soil bank,” Coulter says.
Watch Temperatures
Early-season post-herbicide applications during fluctuating day and night temperatures can impact control efficacy. Daytime temperatures above 55 degrees and sunny with evening temperatures above freezing improve herbicide effectiveness. Extended temps below 40 degrees may benefit from higher herbicide rates or added tank-mix products. Be sure to check the herbicide label.
Any weeds that emerge beyond an initial post application may not be enough to reduce yields. However, if these weeds include herbicide-resistant species like giant ragweed, marestail, waterhemp, kochia and Palmer amaranth, they will likely build the weed seed soil bank, resulting in higher future input costs.
Coulter reminds growers that more scouting and the use of integrated weed management tactics, along with herbicides, can help overall weed control success when planting early.
Drill down for more info:
- Cold Soil Temperature and Corn Planting Window
- Corn Growing Degree Day Tool
- Window of Opportunity for Corn Planting: Data from Across the Corn Belt
- The Relative Impact of Crop Weather Variables on the U.S. Average Yield of Corn
- What Do We Know About Planting Dates and Corn and Soybean Yield from Agronomic Field Trials?
Content provided by DTN/The Progressive Farmer
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