A Strip-Till Skeptic
Although interest in strip-till (and zone tillage, which is similar but includes deeper tillage in the strip) is surging, not everyone is an advocate of the practice. One skeptic is University of Nebraska ag engineer Paul Jasa. It's not that strip-till doesn't work, he says—it's just that he believes farmers can accomplish the same objectives, for less cost, with no-till.
That includes farmers on poorly drained soils in higher-rainfall areas, such as the eastern Corn Belt, where strip-till is used to dry the soil for planting. "If you have excess water, a better solution is to grow it out with a cover crop or intensify the cropping system to have something growing when water is available,” Jasa says.
Close considerations. The same argument applies to warming the soil, which strip-till does by clearing away residue. "Wet soil is colder because heat is required to warm both the water and the soil,” Jasa says. "If the soil structure is such that the water near the soil surface can infiltrate and the residue isn't matted down, so air gets to the soil surface, the soil will warm up naturally without strip-till. During the heat of summer, cooler soil, with residue over the row, results in better rooting, standability and water uptake.”
Strip-till can provide a sense of security, Jasa says. "Some farmers are afraid of the residue left on the soil surface in no-till,” he adds. "If they spend some time in the tractor seat, burn some fuel and blacken some soil, they sleep better. The crop comes up a little quicker when it's planted into a blackened strip—but none of my strip-till trials have yielded any better than properly managed no-till.
"I'd rather leave residue across the entire soil surface and build uniform soil structure, with uniform moisture, using no-till,” Jasa says. "Doing tillage in a strip creates a nonuniform rooting zone.”
When you evaluate strip-till, consider equipment cost, Jasa advises. "When studying data, make sure the systems to which strip-till was compared were properly managed,” he says. "No-till is a systems approach, and it must be done continuously to get the soil benefits. Planting a crop one year without tillage is not no-till because the soil will still have a tilled structure. Also, with no-till, the cropping intensity must be increased.”
Jasa has prepared a short paper addressing questions he receives from farmers about strip-till versus no-till. You can access the paper at http://cropwatch.unl.edu
or e-mail Jasa at firstname.lastname@example.org