Missouri farmers itching to plant corn find that soil temperatures are well below the 13-year average, according to University of Missouri Extension specialists.
Soil temperature, not air temperature, controls seed germination, said Brent Myers, new MU Extension cereal crops specialist. Soil temperature nearing 50 degrees Fahrenheit at 2 inches is a good target to begin planting for corn. It takes about seven days for corn to germinate and emerge. Early emergence could result in exposure to late frost. Late emergence leaves the seed in the soil longer and increases risk of disease.
At the end of March, soil temperatures in mid-Missouri inched up toward the 13-year average, according to Horizon Point, a custom weather-analysis service from the MU Commercial Agriculture Program. Air temperatures reached 67 degrees on the last day of the month, pushing soil temperatures above the 50-degree mark for the first time in 2013. Temperatures were average to 5 degrees below average, with nightly temperatures ranging from 30 to 42 degrees.
An April 8 USDA crop report showed that Missouri farmers had tilled only 25% of the ground, compared to 61% this time last year. The five-year average is 24%. The most recent report has 4% of the corn planting completed, four days behind normal.
There is still plenty of time for planting, said MU Extension agronomy specialist Bill Wiebold. Thanks to technology, all of Missouri's corn crop can be planted in one week when conditions are right, he said.
The average date of the last spring frost in mid-Missouri is April 10, but northern Missouri remains vulnerable through April 20.