Underground Movement - 15

By Susan Winsor
Progressive Farmer Contributing Editor

Paul and John Dubbels parked their soil finisher and chisel plow in the 1980s after an inch of spring rain carved gullies in their newly finished field. They'd run a disc chisel the previous fall, but farm-rolling highly erodible land near Fergus Falls, Minnesota, and seeing that much erosion was unacceptable.

Today, they spring strip-till corn and continue to no-till soybeans. For farmers looking to streamline agronomics and cut soil loss, there are lessons aplenty in their 33-year tillage journey taken on their west-central Minnesota clay soils.

"Paul and John have successfully no-tilled and strip-tilled for many years," said Jodi DeJong-Hughes, University of Minnesota Extension educator, crops. "That's quite a feat, being so far north."

"People said you have to really work those eroded yellow clay hilltops to get a crop from them, but when we stopped tilling them is when we really got nice crops," Paul said. Besides farming with his brother, John, Paul Dubbels is a seed manager for CHS-New Horizons Ag, based in Herman, Minnesota.

TILLAGE TRANSITION

The Dubbels brothers tried no-till wheat and soybeans in 1982 and began ridge-tilling corn about the same time. When rainfall patterns became too wet to build ridges, they switched to no-till corn and soybeans for another couple of decades. However, trying to put enough fertilizer on with the planter was an ongoing issue. That's when they turned to strip-till.

Environmental Quality Incentives Program (EQIP) funding in 2007 helped the Dubbels purchase Dawn Pluribus spring strip-till units, making strips 8 inches wide and 5 inches deep. "We used it for tillage only and continued applying fertilizer with the planter," Paul said. "Adding more work and no yield gain [compared to no-till] made us pretty half-hearted strip-tillers for a few years."

In 2013, they decided to get the fertilizer off of their planter and set up a strip-till bar with a Montag cart. Paul likes the ability to put 100% of the fertilizer into the strip without additional trips. "We can carry 8 tons of fertilizer with the Montag compared to 2 tons on the planter," he said. "A big reason for strip-till's success is incorporating your fertilizer." Adding all of the nitrogen (N) in the strip didn't burn the seed, as long as they applied the total fertilizer blend (N, P, K, Su, Zn) below the seed.

The slopes the Dubbels farm have caused them to modify their strip-till unit to form slightly narrower strips to address the hilly terrain and erosion concerns. "The smaller strip also prevents the soil from drying out and forming clods [baking]," Paul said.

RESIDUE-FREE STRIP

Managing residue begins with a Case IH 1083 corn head (with knife rolls frequently replaced to keep a square, sharp edge) to chew stalks down to about knee-high. "In our no-till days, chewed-down corn stalks and rolling after soybean planting was all we needed to keep up with residue," Paul said. A chopping head isn't necessary. In a wet fall, it leaves a wet mat on the ground; and it takes more power, he added.

"The key to making strip-till work is row cleaners pushing residue aside, then the planter row cleaners move it further, creating a reasonably clean strip," Paul continued. "Some people think the 'till' part of strip-till makes it work, but it's actually the residue-free fertilized strip." Residue drifting back in the row after planting is less of an issue when strips start out clean and is the reason they strip in the spring.

The Dubbels went from an eight-row to a 16-row planter and didn't gain much. "Filling fertilizer boxes was a real drag -- something had to change," John said.

They traded their 16-row, pull-type planter for a new 12-row semimounted planter and strip-till bar because they didn't think 3-point-hitch implement steering could handle 16 rows. The brothers removed the fertilizer openers from the old planter, stripped everything off the old Pluribus units, put single-disc openers on and fed them with a Montag cart.

After various configurations, they ended up putting on Ausherman/Great Plains single-disc fertilizer openers the third year. They've used them since the 1980s on their planter for both ridge-till and no-till.

"After easily running 12 rows for a year, we thought returning to 16 rows would be easy," Paul said. "Steering 16 rows worked fine, but turning on steep headlands didn't work well. We removed the row-unit gauge wheels to shed weight and now run without any -- openers will go to the depth of their hubs and run OK. We may add some type of closing wheel to break up occasional ribboning in wet clay. Our current configuration probably doesn't pull much harder than a central-fill planter."

It's so hilly in west-central Minnesota they have RTK (Real-Time Kinematic) steerable 3-point hitches on their strip-till bar and planter. "No question, no-till is easier and far simpler," Paul said.

THE TRADE-OFFS

The bottom line is the Dubbels' system allows them to stick with spring strip-till to get all of their fertilizer down in one spring strip-till pass and "to get the fertilizer off the planter," Paul said. "We never tried fall strips since our lightweight units would not penetrate fall soils, and shank machines in the area had issues with conditions being too dry or too wet. After years of no-till, we weren't interested in going back to fall tillage. We are also concerned with washouts from spring snowmelt."

One issue with spring strip-till is wet soil. "In our no-till days, if we could walk across the wet areas, it was firm enough to plant, even if it was squishy," Paul said. "We could never make that work in our tillage days -- our soil structure wasn't there. We were concerned that strip-till would lead to clod problems like we had with tillage."

In extremely wet fields, they leave the strips to dry out for a day or two before planting. "We keep working on settings and modifications such as fertilizer-tube adjustments to accommodate wet conditions," Paul said. "We typically follow with the planter hours after a strip-till pass, which is often enough time to see a little dust."

ADD COVERS

The brothers began experimenting with cover crops two years ago. Although it can be a challenge to establish cover crops before a frost, their experience no-tilling into pasture convinced them of the merits. "Thanks to outstanding soil structure with internal soil drainage, the corn emerged looking green without issues. Harvesting 200-bushel corn and 50-bushel beans with sod and cowpies still intact was as good as it gets," Paul said.

He sees cover crops are one way to mimic the prairie with year-round growth, building soil structure with internal drainage and allowing soil to warm up while remaining covered. The year-round roots also improve soil structure and organic matter, even on hilltops.

"I think over time, cover crops might take soil structure to a new level and allow a switch back to no-till," he added. Increasing earthworm populations are further confirmation of improved soil structure and soil health.

Jill Clapperton, principal Rhizoterra Inc. scientist, called worms ecosystem engineers. "They dramatically improve soil structure, they're severely affected by disturbance, and they benefit strongly from crop diversity and rotation," she said. "If a shovelful of Corn Belt soil has fewer than five earthworms, you have work to do [to improve soil health]. If it has eight, you're good. If you have 10 to 12 earthworms, that's excellent; and if you have more than 12, that's outstanding."

Worm castings and heavy residue are a new look and language for many farmers. "We're fortunate to have understanding landlords with an interest in soil conservation who are strong supporters of maintaining residue-covered soil and appreciate seeing their farm survive heavy rains without gullies," Paul said. "Many are lifelong farmers who understand that high-residue farming looks a little different."

(ES/AG)

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