Editor's Note: This is a continuation of Steps to Strip-Till Success (Part 1)
If you switch from conventional tillage to strip-till, you may need to manage winter annual weeds in the fall (just as in no-till) because you won't be controlling them with spring tillage.
"If your field has a history of winter annual weeds, it's wise to treat them in the fall,” Baer says. "Winter annuals don't show up as much the first year you strip-till. But after three or four years, populations take off.
"A fall herbicide treatment is pretty economical,” Baer continues. "Several products kill all three of the primary winter annuals: henbit, chickweed and marestail. In the spring, after the weeds have been growing all winter, they'll be ten times as difficult to control.”
In the spring, you will want to add a burndown herbicide to your residual product, Baer adds.
In continuous corn, if harvest is late and some ears fall off, you may wind up with volunteer corn in the following crop. "Although this situation doesn't happen often, volunteer corn could be an issue if you're growing Roundup Ready hybrids back-to-back,” Baer says. "The only solution would be to switch to a LibertyLink hybrid.” You can minimize the risk by scouting fields and prioritizing which ones need to be harvested first.
If you're converting from conventional tillage to strip-till, you will also need to spend a little more effort on disease management because disease organisms overwinter in corn residue. "In the Farm Journal Corn College demonstration plots, we found two to three times as much disease in the strip-tilled corn as in the plowed ground,” Ferrie explains.
"Disease threats vary by region; a major one here in central Illinois is gray leaf spot,” Ferrie continues. "But disease is not a big deal if you understand the situation and manage around it. Select hybrids with higher disease pressure in mind. Plan to scout fields to determine whether a fungicide is needed.”
When strip-tilling or using any other tillage system, continuous corn is tougher than a corn–soybean rotation.
"Successfully strip-tilling continuous corn depends on your location,” Ferrie says. "In northern latitudes, with a great deal of residue, it is a challenge—you have to fight a lot of residue in the spring because less of it decomposes in the fall, and the residue increases disease pressure. In southern latitudes, strip-tilling and no-tilling continuous corn is easier.”
In one field of continuous corn, the Endresses found strip-till yields were not keeping up. "So we tilled the field,” Tom says, "pulling the same type of ripper tool we had used in conventional tillage. In those days, our tractor struggled to pull it; but after strip-tilling for a few years, it walked right through.
"Although tillage helped boost yield that year by getting rid of some of the residue, we decided the damage to the soil structure wasn't worth it. So we went back to strip-tilling. In addition, we have also seen a field of strip-tilled continuous corn produce our best yield.”
Although it's not practical in every field, the brothers have found that pasturing cows after harvest makes it easier to strip-till continuous corn by reducing the volume of residue. "Our best continuous-corn yields are in the fields that are pastured,” Tom says.
In continuous strip-till corn, harvest technique takes on added importance. Wheel tracks from combines and grain carts (as well as manure spreaders) can make it hard to apply ammonia. "Strip-tilling into ruts doesn't work,” Ferrie says. "You can't build a good ridge in a 6" rut. If you're applying anhydrous ammonia, the soil won't seal.
"If a landlord demands that you mud a crop out, you'll have to till to fix the ruts. I continue to see growers try to strip-till into rutted fields, and the result usually is a disaster.”
You'll need a backup plan for strip-tilling and nitrogen application if weather prevents you from making strips in the fall. "If you don't get strip-tilling done in the fall, you'll have to do it in the spring,” Ferrie says. "We recommend against applying anhydrous ammonia with spring strip-tillage; the risk of seedling root burn is too great. Run only the strip-till bar, and don't take a chance on nitrogen smoking your corn stand.”
The ideal setup for your strip-till bar will depend on your soil and conditions. A number of manufacturers make toolbars and planter attachments for strip-till application.
A properly built strip is the key, Ferrie emphasizes. "The better job you do of making the strip, the better it overwinters, and the better you maintain depth as you plant, the better stand you will have,” he says.
"When you make your strips, if your tractor has extra power, resist the temptation to go too fast and explode the soil,” Tom adds.
Good strips provide a seedbed almost identical to conventional tillage. "We like a row cleaner with a depth gauge on our planter,” Tom says. "But you really don't need to modify your planter much. A planter that works in conventional conditions should work for strip-till.”
Ferrie recommends row cleaners in any tillage situation, not just strip-till. "Whether or not you need a coulter with the row cleaner depends on your soil type and how well you built the strip,” he says. "If you run a coulter, don't set it too deep; run it ¼" to ½" above where you place the seed.”
An auto-guidance system for your tractor makes it easier to stay centered on the row when you plant, Ferrie says. At Purdue, Vyn observed higher in-row soil temperatures when RTK auto-guidance was used to place corn rows directly in the center of the strip. His three-year study involved corn planted into soybean residue.
Auto-guidance also makes it possible to control traffic and keep wheel passes between the rows, Vyn says.
Be cautious about using strip-till on slopes greater than 5% or so, he says. Especially following soybeans, it may not leave enough residue cover to protect against erosion.
You can e-mail Darrell Smith at firstname.lastname@example.org.