After 11 years of strip till, Dennis Smith has built his night crawler numbers up to the point that there’s not enough soybean residue to go around.

“The earthworms are pulling the residues down into their holes,” the Story County, Iowa, strip tiller explains. “With soybeans in the rotation, I can’t get enough residue.” He likes the residue conversion for soil-building purposes, but also wants residues left on the soil surface for protection against erosion.

Smith remembers the soil erosion he saw in the 1980s after he started farming with a heavy disk and field cultivator in 1984. “In the 80s, we just wanted to get to the 90s,” Smith says. “Erosion was terrible around here. I wanted to avoid that, and I wanted a better way to apply fertilizer. Two big technology changes in the 90s—Roundup and guidance systems—started me thinking about strip till.”

In fall 2004, Smith took a look at the strip till machine fellow Story County farmer Mike Hermanson had built to apply fertilizer in the 10-inch wide and 10-inch deep tilled strips he was preparing for planting the next spring. Hermanson attached Soil Warrior row units to a planter tool bar and added a grain cart frame, fertilizer components, and other parts to build his own strip till machine.  He pulled it with a 9400T Deere tractor with AutoSteer.

Parked field cultivator in 2005

“I rode along with Mike, and liked what I saw,” Smith says. “I used the field cultivator in spring 2005 for the last time. That fall, I brought in a Soil Warrior that tilled 10 inches deep and applied dry fertilizer in the strip. The next spring, I applied 32% liquid nitrogen. We used the machine for seven years of corn on corn.”

After a severe corn rootworm problem in 2012, Smith set the strip till machine for shallow tillage to prepare for soybean planting in 2013. He’s found the bumped-up earthworm and soil microbe populations that come with strip till are consuming crop residues much faster than with full-width tillage.

“The earthworms pull the residue down into their holes,” Smith says. “They don’t like the tilled zone, but the untilled area is a haven for them. I can’t get enough soybean residue.”

Waterways, pattern tile not needed

Smith says grassed waterways aren’t needed on his farm because water infiltration is so much better with strip till. The farm isn’t pattern tiled, but Smith says that’s also unnecessary because his soil structure is significantly improved. His soil organic matter content also jumped. “We were lucky to be at 2½% before, but now we’re from 3½-5% organic matter,” Smith says.

He especially likes the way the units work in wet soils. “It’s really no different than using a field cultivator in the way it dries out soils. We’ve had some terribly wet conditions in the spring—I’ve pulled the machine through standing water, and was surprised when every piece of corn grew,” he says. “You can sometimes plant within hours of running the machine. Our zones have actually dried out too deeply at times after we’ve run the machine.”

Better corn root growth

Smith says he’s seen much better corn root growth early on at what he calls the ugly stage, because of well-placed fertilizer with strip till. He hasn’t seen much difference in weed control or fuel use compared to full width tillage. He sold his field cultivator, but did use his ripper on end rows last year. “It was a big mistake,” he says. “It was the worst place in the field, because I lost the soil structure I had built.”

Smith says there is a learning curve with strip till, and you have to commit to the time it takes to see soil changes. But he’s happy for making the change. “It’s a mindset. You’d never, ever get me to go back to full width tillage. There’s so much flexibility with this system, I wouldn’t farm any other way.”

Environmental edge with strip till

Fifteen years of data shows that year in and year out, strip till matches full width tillage systems in yields, says Dr. Mark Licht, Iowa State University cropping specialist. Research at other universities indicates similar yield findings.

Why, then, ISU Engineer Dr. Matt Barr rhetorically asked farmers at an ISU field day in July, is ISU beginning a field-scale research project comparing no-till, strip till and full width tillage systems?

“Iowa State University was very much a part of developing the nutrient management strategy that calls for a 45% reduction in nitrate and phosphorus in water leaving the farm,” Barr says. “So we want to be as helpful as we can to assist farmers who are voluntarily trying to meet those goals. We can achieve 45% reduction of phosphorus with strip till.”

In addition to that environmental edge, Darr said the flexibility of putting down in-zone fertility is appealing. ISU is testing various amounts of fertilizers in strip till. First-year research shows higher in-zone fertility can result in two V-stage growth differences in early corn plant development. “That may not convert to higher yields,” Darr noted, “but it’s something we’ll watch.” The field-scale comparisons are also helping ISU researchers learn first-hand about machinery operations and other areas of strip till that they can relate to farmers new to the practice.