By Brian Ojanpa
Free Press Staff Writer
MANKATO — Don’t let all that late-winter snowpack and recent inch-plus rainfall fool you.
Underneath all that moisture, below that frozen ground, drought-ravaged soils remain as parched as a mummy’s mouth.
What that bodes for plants and planting this spring, which officially starts today, might revolve around two words: April showers.
Average rainfall would be good, above-average even better. But if the arid conditions of last summer and fall persist into spring, hit the hoses early.
“As the snow melts and the ground thaws, we do get some moisture into the soil,” said Betty Koberoski of Edenvale Nursery in Mankato. “But if we don’t get adequate rains in April, then people need to start watering.”
She noted that intensive watering should have been done late last fall for the benefit of many trees and perennials, as evidenced by the abundance of brown-needled evergreens she’s seeing.
All the more reason to pump water into the ground this spring if nature doesn’t.
Koberoski’s rule of thumb if normal rains don’t come: Start watering when the ground starts to shed its frost and plant budding can be seen.
Soils in the Mankato area remain in severe to extreme drought status as April approaches.
Jeff Vetsch, an assistant scientist at the University of Minnesota Southern Research and Outreach Center in Waseca, said the 1.5 inches of precipitation in the current snowpack will be of little use on farm fields because much of it will simply run off the frozen ground.
That’s a boon for the replenishment of rivers and lakes with woefully low water levels, but a bane for crop soils with deep thirsts.
Vetsch said when the final fall soil tests at the center were done Nov. 16, there were 3.63 inches of available moisture in a 5-foot sampling profile.
“That’s 33 percent of full-capacity moisture in the soil.”
In this area, he said rainfall averages 3.2 inches in April and 3.9 inches in May.
“If we have normal rainfall and normal evaporation in April and May, we should have near normal soil moisture capacity by the end of May,” Vetsch said.
And in areas of the state where the drought is more severe, average rainfall of 6 to 8 inches March through May still won’t be enough.
“To replenish those desperately dry subsoils, we’ll have to exceed that 6- to 8-inch amount,” said State Climatologist Greg Spoden, who likened the soil beneath the frozen landscape as “dust beneath the concrete.”
He said current conditions haven’t been seen since the drought years of 1987-88.