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Corn+Soybean Digest


The beauty of a plowed field doesn't escape Norm Larson. He'd just rather limit the tillage to narrow strips, rather than fence row to fence row.

That's a tough argument to make on the heavy, wet soils of northern Illinois. Tradition says plowed fields produce big yields. Today's economy, however, makes a strong argument to limit those heavily tilled soils to narrow strips.

“Strip-till won't increase your yields. They're the same as tilled ground,” says Larson, agronomy sales manager for Elburn Co-op, Sycamore, IL. “It's not about better yields; it's about better economics. You have to look at the cost of tillage, the environmental issues and the efficiency you gain by banding fertilizer close to the seed.

“The trick is to build strips that look like plowed ground,” Larson says. “We want a strip of black soil with a berm. Then the freeze and thaw of winter develops tilth and a nice, soft seedbed to plant into in the spring.”

There's a smorgasbord of strip-till equipment to serve that growing market. The question is, what works and how do you adjust it? For answers on how to set up the co-op's two strip-till machines, a 16-row DMI 5310 and a 12-row John Deere 2510 S, Larson called Maxwell, IA, consultant Kevin Kimberley. He travels the Midwest working with farmers to adjust their strip-till equipment to match their field conditions. He's seen just about every option available and has definite opinions on what works and why.

“Just about any setup will work some years, depending on the weather and soil conditions. I want to put together a machine that will work every year,” Kimberley says.

“It's a marriage between your planter and the strips you create,” he says. “It's not rocket science. But screw it up and you've got a divorce.”

IT ALL STARTS at the front of the strip-till machine. Kimberley jettisons the straight-edge coulters that come with strip-till rigs in favor of the Great Plains Turbo coulter. “Most guys want to run a straight coulter 4 in. deep and their fertilizer knife 7-9 in. deep. The coulter tends to smear the sidewall, and the knife explodes the soil leaving large air pockets under the surface,” he says. “We set the Turbo coulter as deep as the knife so the knife runs in loose soil. You don't get that explosion so there aren't large air pockets and you're not throwing dirt.”

Depending on a machine's toolbar configuration, Kimberley mounts a Yetter SharkTooth trash wheel with a floating arm, directly in front or behind the Turbo coulter. “The Yetter units have a floating arm but you can pin them solid if you need extra down force when the soil and residue are wet and heavy. But in most cases, you want the units to float,” he says. “I prefer the Yetter units because they work in all conditions. They move the residue without hairpinning and they don't plug with wet soil or trash.”

Kimberley prefers to run two coulters ahead of the fertilizer knife and mounts them 4 in. off center, set to run 4 in. deep. He'll use either a ripple coulter or a straight-edge coulter depending on soil type. “I recommend a straight-edge coulter on soils that tend to be wet and sticky because the ripple coulters will throw too much soil,” he says. “The two coulters work the soil without throwing clods or creating big air pockets. If you get off center when you plant, you've still got a 4-in. profile where the root mass can grow.”

In the fall, Kimberley uses a standard mole knife to place fertilizer in a band. “Everybody is doing something different with fertilizer,” he says. “Some are putting down liquid P and K in the fall and coming back with 28% in the spring. Some guys just put on anhydrous ammonia, others band dry fertilizer along with the ammonia.”

For spring strip-tilling, Kimberley switches to a narrow coulter in front and a narrow fertilizer knife to minimize moisture loss.

It's important to remember that the mole knife places fertilizer; it's not a primary tillage tool, points out Larson. “It's not a deep ripping machine,” he says. “If you have fields with compaction problems, you need to run a deep ripper over them the year before you switch to strip-till.”

Kimberley likes to run 13-wave closing coulters on both sides of the fertilizer knife. “We run the 13-wave coulters beside the knife, trapping dirt to create the berm,” he says. “Otherwise, the dirt tends to blow out the sides of the normal closers.”

Contrary to most manufacturers, Kimberley isn't a fan of rolling baskets. He prefers to have the coulters control the final clod size. “Baskets tend to either pulverize the soil, or let the clods just slip through,” he says. “In a lot of cases, farmers end up bolting them up, out of the way. I'd rather see farmers spend their money on coulters than rolling baskets.”

Larsons says: “We've tried different rolling basket designs and, if we're going to use one, prefer units that have concave bars that help shape the berm.” But like Kimberley, he notes that most of the time the baskets end up bolted up, out of the way.

The end product with Kimberley's system is a black strip with clods roughly the size of half a fist. “Aggregate size is important,” says Larson. “I like to see uniform aggregate size from 3 to 6 in. Soil pieces that size won't blow or wash away. It's important that the soil aggregates are uniform because there's no additional tillage to reduce their size. Although, residue movers on the planter will kick them out of the way.”

KIMBERLEY SAYS: “You want a berm that's 3-4 in. tall. Any bigger than that and you have to be concerned about air pockets underneath the soil. A strip-tilled field sometimes looks terrible in the fall, but in the spring you'll have beautiful, black strips to plant into.”

At least you hope you'll plant into them. A critical component in strip-till is to match the width of your strip-till machine to the width of your planter, according to Kimberley.

“Most planters are pull-type and I've seen them drift as much as 10 in., even on flat soil, because the machine looks for the easiest place to run. You need to index your planter and strip-till machine so the drift of each machine will match,” he says.

“I've even seen drift in fields where guys are using RTK,” adds Larson.

There's definitely a psychology to strip-tilling, according to Larson. “We split the old rows so when we're done there aren't any standing stalks. For some reason, it really bothers guys to see standing stalks in the field,” he says. “They need to feel like they've done some work.”

Larson believes there's a good argument for a light tillage pass ahead of creating strips in the fall. “There are new machines on the market that help size the residue so it's easier to move with the strip-till machine.

“I'm not an advocate of chopping stalks, because they'll blow. But it's helpful to size the residue so it's less than 12 in. long. Six to 12 in. is the best,” he says. “It's easier to move residue that size if it's wet, and sizing it helps start microbial activity to break it down. That's particularly important as we see more corn yields of 250 bu. or more. That's a lot of residue to contend with.”

This fall, however, most fields that the Elburn Co-op custom stripped didn't have any tillage ahead of the strip-till machine.

Larson figures strip-till, including custom application rates, saves growers $32/acre in reduced costs — with no yield bonus or drag with normal northern Illinois rain patterns.

In drier regions, Kimberley notes, you'll likely see a yield bump. “Strip-till really shines in a dry year. The root mass is just phenomenal,” he says. “In a wet year, you won't see any significant differences between strip-till and tilled fields. Mother Nature cures a lot of ills.”

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