Mark Lawson, farmer and regional technical rep for Syngenta, pays attention to details. Soil temperature is one of them. It can help determine when soil temperatures should be getting close to warm enough for corn seed to germinate. It can also be an indication of insect activity in some situations.
Hendricks County experienced the same cool spring most of Indiana has seen, with a big snow during the last week of March. However, once the snow melted Lawson soon began measuring soil at 7 a.m. each morning at a 4 inch depth, on a bare spot. That's the standard operating procedure for taking soil temperature readings, he says. If the temperature is taken in a sod situation, then the report should indicate that the area was covered by sod.
When Lawson checked soil temperatures in his field during the first week of April, he found a reading of 39 degrees F. By Friday, April 5, the soil temperature was into the low 40-degee F readings.
Surprisingly, by April 9, just a few days later, the same thermometer at the same location indicated a soil temperature of 53 degrees F, marking an increase of nearly 15 degrees in less than a week.
"We had several days of fairly warm temperatures and some sun," Lawson says. "It can warm up rather quickly."
Soil type can also play a role in how quickly soil warms up. In addition, what goes up can come down. Decrease in ambient temperature since then may have slowed soil temperature increase, stalled it out or even sent it backwards.