As of April 27, the USDA-NASS says that only 8% of Indiana's corn crop had been planted, compared to an average of 26% over the past five years. While soil moisture in most places has been acceptable, it is the cool weather and low soil temperatures holding farmers back.
"Corn should not be planted until soil temperatures are at or near 50 degrees," says Mike Deutsch of AgriGold. "It should take about 3 weeks for corn to emerge at 50-55 degree soil temperatures. If you wait to plant when soils are warmer, the corn should emerge in as little as a week," he says.
A seed's first drink should never be cold. Once in the ground, a kernel naturally swells, bringing in that moisture. But if the soil temperature is cold, soil moisture is cold as well. Cold soil temperatures during the initial 24 to 36 hours after seeding risk imbibitional chilling injury, according to R.L. Nielsen, Purdue Agronomy Department.
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Imbibitional chilling injury occurs when the kernels imbibe cool water and begin the germination process. When cell tissues of the kernel are too cold, they become less elastic and could possibly rupture during this swelling process. Kernels will appear swollen and therefore in the process of germination but will fail to exhibit further signs of growth.
Neilson suggests hedging your bets:
• Within reason, avoid planting extensive averages when soil temperatures are not conducive to rapid germination, emergence and early seedling development. The definition of 'conducive' basically means average soil temperatures consistently greater than 50 degrees Fahrenheit. For central Indiana, such soil temperatures typically occur beginning about the third week of April. However, this spring isn't typical. It's the first time in a decade the thermometer didn't hit 80 degrees F before May 1.
• For early planting, plant your best quality seed with the greatest seedling vigor ratings. Save poorer quality seed lots and/or hybrids with lesser seedling vigor rating for later plantings when temperatures should be more favorable for germination, emergence and early seedling development.
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While we are into May already, temperatures are taking their time warming up and soil temperatures tend to follow suit. While most have started planting, checking soil temperature as you move fields is still a good idea.