By following several guidelines, fall strip-tillers can increase their chances for success, says Greg Willoughby, technical manager for Helena Chemical.
“First, recognize that the soil-moisture range in which strip-till can be done successfully is smaller than the range for other fall tillage operations like moldboard plowing or chisel plowing,” Willoughby says. “Strip-till should be done when the discs behind the shank can form an optimum ridge without excessive clods.”
This berm has to be sufficiently level to plant into the following spring, he says. Both freeze-thaw cycles and tined row cleaners provide additional flexibility in how smooth the berm needs to be in the fall.
“Adjust the shank depth to at least 4 inches and perhaps as much as 8 inches,” Willoughby says. “This will result in sufficient soil loosening to accelerate drying in spring, and enough loose soil for the discs to shape a berm 3 to 4 inches higher than the untouched areas. Corn yields have typically not benefited from strip-tillage any deeper than 8 inches.”
Deeper depths require considerably more tractor power to achieve at recommended forward speeds for the operation — about 5 to 6 mph, Willoughby says.
Regardless of shank depth, the overall objective of berm formation should be to conserve a slightly raised and loosened row area to plant into the following spring.
“Don’t become overly dependent on the capability for fertilizer banding that often accompanies strip-till,” Willoughby says. “It is not always a good idea to deep-band multiple years’ worth of the estimated phosphate and potash fertilizer requirements in a single operation.”
Even when strip-tillers deep-band fertilizer, there may still be a yield benefit associated with the traditional starter fertilizer application at planting, he says. For instance, very high rates of deep-banded potash fertilizer have been observed to negatively affect early corn growth rates relative to broadcast applications.
Deep banding can accentuate horizontal stratification of the less mobile nutrients, Willoughby says. There needs to be some assurance that narrow-row crops planted between the nutrient bands in subsequent years aren’t yield-limited because of relative nutrient availability.
“Corn plants generally grow at a faster rate and silk emergence, along with final maturity, often occurs 1 to 2 days earlier even when strip-till corn is planted on the same date as no-till corn,” Willoughby says. “Although corn yields are generally no better with strip-till than with no-till for corn after soybeans when planting dates are the same, strip-till corn generally yields higher than no-till corn when corn follows corn, winter wheat or other rotations with high residue cover.”
Strip-till also has benefits vs. conventional tillage, Willoughby says.
“Strip-till results in corn growth rates and final yields that are usually equivalent to those after conventional tillage for corn after soybeans and even when corn follows corn, assuming successful strip-till can be done between corn rows after grain harvest,” he says.