Soil temperatures are as expected, according to Jennie Atkins, Water and Atmospheric Resources Monitoring Program manager at the Illinois State Water Survey, Prairie Research Institute, University of Illinois. The November statewide soil temperature average was nearly 5 degrees higher than normal, but the cold snap in mid-December brought temperatures down to a relatively normal level. Soil temps under 4-inch bare soil were in the low 50s in southern Illinois, and in the mid- to upper 30s in central and northern Illinois.
Air temperature and snow cover impact overall soil temperatures, Atkins notes, but 4-inch soil temperatures typically linger between 30 and 40 degrees F during the winter. “There are no real trends toward warmer soils, but we do have peaks and valleys throughout the winter,” she notes.
Soil temps may be right on track, but soil moisture levels are a different story. “Soil moisture numbers are high right now; particularly in the deeper soils — 3 to 5 feet deep — we’re seeing some really saturated soils,” Atkins says. “But even at 2-, 4- and 8-inch depths, we’re seeing some pretty high numbers.”
That means moisture levels are at or slightly above field capacity, she notes.
Will soils stay saturated? Atkins says it’s possible.
National Oceanic and Atmospheric Administration models indicate a few wet months ahead, she explains, with “an above-average chance for precipitation.” That leads to two questions: Will the precipitation be snow or rain? Will soils stay frozen?
Rain on frozen soils will run off, Atkins explains, while snow will linger, melting into the soil and adding to moisture levels.
There are outliers around the state, Atkins notes. Parts of southern and central Illinois are rated “abnormally dry,” according to the U.S. Drought Monitor.
“We’re going to see soil moisture stay fairly decent for a while,” Atkins adds. “Right now, things are looking typical for what one would expect.”
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