Doug Olson owns three 30-ft. Summers Supercoulter Plus vertical-tillage machines with rolling choppers – each with a different blade configuration. After corn harvest, he uses a machine equipped with wavy blades to slice stalks into 5- or 6-in. pieces. The wavy blades also throw some soil, “so you get more tillage effect. I use them in the fall for more incorporation of residue.” In the spring, he uses less aggressive smooth blades “for aeration, to warm the soil and prepare the seedbed.”

Olson’s corn ground gets two vertical tillage passes: one in the fall to size the residue and promote breakdown, and one in the spring to fluff up the residue and loosen soil in the planting zone. Soybeans, which respond less to tillage, get only one pass in the spring, a few days ahead of the planter.

The timing of shallow vertical tillage depends on your goals and soil conditions, says DeAnn Presley, a soil scientist at Kansas State University. If your object is to break down residue faster, a fall pass works best, giving soil microbes more time to work their magic. But you sacrifice the conservation benefits of leaving residue intact over the winter, she says. “One weakness of all vertical-tillage tools is they don’t have a lot of ability to anchor residue in the soil. They cut residue well and leave it on the surface. But if it’s sloping ground or ground prone to wind erosion, the residue can move. We’ve seen that happen in eastern and western Kansas.”

If erosion is a risk, a spring pass is preferable, Presley says. However, a spring operation raises the risk of tractor-wheel compaction, says Purdue Extension Agronomist Tony Vyn.

During several cold, wet springs in northwestern Minnesota and eastern North Dakota, though, shallow vertical tillage was the only practical option for seedbed prep, says Jodi DeJong-Hughes, Minnesota Extension regional educator.

 “It’s shallow, straight, and there are no shanks that can smear the soil. It just warmed and dried the soil enough so people could plant.” In some cases, she adds, “It made the difference between being able to plant and preventing planting.”

MORE VERTICAL TILLAGE: Vertical Tillage Should be Conservative, Shallow