Strip-till is not a perfect corn production system, but research indicates that it has more going for it than conventional (full-width) tillage or straight no-till.
In strip-till, bands of loosened soil are prepared before planting - usually in the fall with fertilizer knives and/or coulters - and that soil is warmer and dryer than surrounding ground at planting.
N, P and K, or any combination of those nutrients, can be injected at the time the strips are made.
At Monsanto research farms in central Iowa and southern Minnesota in 1998, strip-till bettered conventional and/or straight no-till in the following five categories, reports Pete Hill, Monsanto conservation tillage specialist:
* Strip-till left considerably more soil-saving residue than did conventional tillage and nearly as much as no-till. The Conservation Technology Information Center (CTIC), incidentally, classifies strip-till as a form of no-till if no more than one-third of the row width is disturbed.
* Ground that was strip-tilled the previous fall was 2-6 degrees warmer in the spring, between 7 a.m. and 9 p.m., than was conventionally tilled ground. That, Hill explains, is because the strips are slightly elevated and also are more porous than full-width-tilled soil.
* Plants in stripped areas were 2-6" taller than in conventional-till or no-till areas from mid-May until early July (when measurements were discontinued).
* Water infiltration was four times greater in strip-till and no-till areas than in conventional.
* Strip-till yields at the Iowa and Minnesota sites, plus a location in central Illinois, averaged 178 bu/acre. That topped both conventional-till (172 bu/acre) and no-till (168 bu/acre).
Hill says another benefit of fall strip-till and fall fertilizer injection is that starter fertilizer - which is recommended with no-till - probably can be eliminated.
Nevertheless, strip-till has some soft spots.
"Finding time to make strips in the fall is the biggest challenge," notes CTIC's Dan Towery. "It may mean stopping the combine after soybeans are harvested, or finding somebody to make strips while corn combining commences.
"For some farmers, the stripping may need to wait until spring. In that case, it might be better to apply nitrogen as a sidedress. Another spring alternative would be to do a form of zone tillage at planting."
Chuck Read, a Princeton, IL, producer who has converted from no-till to strip-till, is wrestling with the problem of how to best get the fall strips done.
"We have been waiting until after corn harvest, but we may need to pull somebody earlier than that to get the strips made sooner," he says. "It's important to make the strips when the ground is dry - the dryer the better. If you have late-fall rains, the ground never gets warm enough to dry out."
Hill reports that Monsanto and DMI-Case have launched a joint effort that encourages fertilizer-chemical dealers to offer fall strip-tilling as a custom service.
"This is a new service opportunity and we are getting a good reception," Hill notes.
He says a few strip-till farmers are having trouble staying on the strips when planting.
"That problem usually arises when the strips are made too high in the fall," he points out. "Strips should be no higher than 5-6". At that height they normally will settle to 1/2-1" by planting time, and staying on the strips should not be a problem."
Richard Law and his brothers John and Don have been strip-tilling corn for several years in their Atlanta, IN, operation. They report a 7-12 bu per acre increase in corn yields with strip-till compared to the zone-till system they had used in the past.
"We build a 3-4" mound when making strips in the fall," says Richard. "The mounds have settled to 1/2-1" by spring. Except on about 1% of the ground - where water washes across the strips over the winter - we have no trouble seeing the strips in the spring when planting."
Hill says farmers with contoured fields and point rows may have a problem with strip-till. But those fields are usually well-drained, and therefore the soils are sufficiently warm in spring that straight no-till can be used.