Damp Weather Could Delay Corn Planting More

MU climatologist says forecasted rainfall could delay corn planting already slowed by cool spring temperatures.

Published on: Apr 27, 2009

Spring crop planting delayed by cold weather in early April faces more delays by late-April rainfall, says Pat Guinan, University of Missouri climatologist.

Cool temperatures kept soils from warming and delayed corn planting across much of the state in early April. In Columbia, the first 14 days of April were the 10th coldest for that time in 120 years, reported Guinan, a weather specialist with the MU Commercial Agriculture Program.

Cool air kept soil temperatures in the 40s, except in the Bootheel. "We need soil temperatures at least 50 degrees for corn planting," says Bill Wiebold, MU Extension agronomist. "Warm, moist soils encourage rapid seed germination and plant emergence soon after planting." In cool soils, seeds that fail to germinate quickly are subject to rot or insect damage.

Temperatures reaching the low 80s from April 22-26 could give farmers a brief window for planting. However, spring storms with heavy rains are possible for the last week of April.

"It is an unsettled forecast," Guinan says. A Canadian front with below-normal temperatures will meet a moisture-laden air mass from the southeast. The forecast calls for that front to lie from New Mexico through Missouri to Michigan by early in the week of April 27. Heaviest spring storms are forecast over portions of Kansas, Nebraska, Missouri, Iowa and Illinois, a large area of the Corn Belt.
The front is expected to sag southward into Missouri late Sunday. "Significant rainfall of 2 or more inches is possible."

At Sanborn Field, a research plot on the MU campus, average daily soil temperatures did not reach 50 degrees until April 15. Usually soil temperatures average 50 degrees by April 1, with significant corn planting by April 15.

"Prolonged rainfall adds flood risk to low-lying fields over much of Missouri," Guinan says. "Streams in much of the Missouri and Mississippi watersheds are running near to above normal."

In addition to cool temperatures, large areas of the central United States had near- to above-average rainfall during early April. "Soils are wet from Kansas to Michigan," Guinan said. "That follows the wettest year on record for Missouri in 2008. We are drought-free."

Guinan adds that we are in a transition period out of La Nina weather. "Surface temperatures in the Pacific Ocean at the equator are back to normal, leading to uncertainty about Midwestern weather," he says.