By SUSAN BLOWER
Indiana Correspondent

WEST LAFAYETTE, Ind. — Though farmers may be eager to get their crops planted this spring, experts warn against rushing soggy soils.

The steady rainfall, resulting in continually wet fields, “increases the risk for creating compacted soil with tillage,” said Bob Nielsen, agronomist with Purdue University.

“Farmers are anxious to get back to the fields. It’s difficult to decide the risks of compaction, compared with the uncertainty of time.”

Greg Bossaer, Purdue extension educator in White County, cautioned against planting just before a heavy rainstorm, which would increase the effects of compaction. “(At this late date) farmers are going to push a little more and take more gambles. They’re going to work soils that are wetter. But if they see a major rainstorm on the horizon, they should delay,” he said.
In the next 8-10 days, Minnesota farmers will need to switch over to hybrid seed, said Jodi DeJong-Hughes, University of Minnesota extension educator in crops. Many of them have not yet planted much.

“In the next week, I don’t want to call (farmers). They’re a little stressed,” DeJong-Hughes said.

Compared to 2010, very little corn has been planted this year. However, 2010’s ideal April led to a dry July. Nielsen said this spring closely resembles that of 2009, which still produced corn yields that were 8 percent above average in Indiana.

Many factors, such as weather conditions during the summer months, will have a greater impact on yields than time of planting, Nielsen said. “With today’s heavy equipment, try to avoid working ground that is too wet,” he said.
Should compaction occur, adequate rainfall through the summer will aid the plants’ root system, Nielsen said.

“The worst-case scenario is that we dry out after the spring. The soil becomes dry and hard, like concrete, and (with compaction) the effects of the drought begin sooner,” he said.

Tire troubles

The leading cause of compaction is wheel traffic in wet soils.

“Studies have shown that the wetter the soil, the deeper the compaction occurs. When dry soil compacts 18 inches, wet soils will compact 24 inches, at the same axle load,” according to a statement by Titan Tire Corp.
In a USDA Agricultural Research Service (ARS) study, a combine with a 20-ton axle load was driven over a dry field with no change in crop production. That same combine driven over a wet field caused a 30 percent loss in yield, DeJong-Hughes said.

Compaction, occurring most often in heavier clay soil, will inhibit root growth, leading to a lack of nutrients. With today’s heavier equipment, compaction is a concern every year, DeJong-Hughes said.

“You want to eliminate the compacted zone to maximize root growth, which will in turn maximize nutrient and water uptake, to promote overall plant health,” said Kip Balkcom, USDA agronomist for the ARS in Auburn, Ala.

In Alabama, the soil is sandy and compaction is less of an issue, he said. Still, he stressed the importance of staying off soil that is too wet.

Balkcom said farmers should check fields for possible nitrogen loss, especially if that field has ponded.

Corn-on-corn fields will be most affected by nitrogen loss, DeJong-Hughes added.

Nielsen said a field’s readiness is determined best by experience on that field. Farmers know their land the best.

“Before they work the ground, they’re getting out of their tractor and scruffing around,” he said.

And that, according to Nielsen, is better than any general rule of thumb from someone behind a desk.