When you watch Bryon Kittleson plant corn you almost do a double take. He’s pulling two 12-row planters, one in front of the other, and he’s planting in twin rows.

The Welcome, MN, farmer has been experimenting with twin rows on corn and soybeans for eight years. “All of our side-by-side tests (30 in. vs. twin rows) have shown a 4-5% yield bump with twin-row corn,” he says. “On beans, we usually see a half- to 3-bu./acre advantage with twins.”

For Kittleson, twin rows on corn mean he’s planting two rows 5-1/2 in. apart on 30-in. centers using two White 6900 planters. That 5-1/2-in. spacing allows the corn head to easily harvest without losing ears. Earlier, he found problems at harvest when he planted corn in 7-8 in. twins.

For soybeans, he’s using 2-1/2 in. cylinder stops so twin row beans are planted 8 in. apart. For the last six years he’s been all twin rows on 500 acres. In 2007 he added the second White planter. Before that he was pulling a modified JD 7100 behind the front White 6900.

“I’m not trying to plant in a perfect Z pattern with my setup,” Kittleson says. “It’s more of a jagged pattern. And I don’t set the planters at the same plant population. I set the front one 18% higher than the back one so it gives us fewer plants that end up side by side.”  

Kittleson has tried 15-in. rows, too. On soybeans he saw a little boost in wet years, but more in a dry year. “With our heavy soil and use of manure, we ended up with a lot of white mold problems on soybeans,” he says. “We get less white mold with twins because there’s more air circulating between the rows. Also, I found that I needed to cut plant populations in fields with white mold problems.”

Nailing the right plant population rate is a trick, Kittleson admits. Two years ago he planted beans at a 166,000 population rate, the next year 155,000 and last year he was at 140,000. He now plants corn at 34,500.

He hasn’t observed any real downside to twins. In fact, when it comes to wind damage, he’s found the twin rows usually stand better than corn in 30-in rows.

“I wanted the yield gains from 20-in. rows, but I didn’t want the costs of trading planters or having to buy a new corn head,” Kittleson says. “That’s when I decided to try the twin-row idea.”

The first year he tried twins on corn, he did it on 37 acres behind the house – so the neighbors couldn’t see. Those days are long gone, however.

In fact, Kittleson is now cooperating with the University of Minnesota in a two-year twin-row study looking at plant populations on twin rows vs. 30-in. rows. Results are pending.

Consistent yield advantage?

Although twin rows work well for some farmers, the verdict’s out on whether you’ll consistently see a yield advantage.

In 2009, Ohio State University corn research plots comparing 8-in. twin rows to 30-in. rows showed no significant difference.

“The twin rows were planted in staggered spacing. And since some hybrids and plant populations may influence corn response to twin rows, we used hybrids with varying maturities (107-, 111- and 112-day) and four plant populations (28,000, 33,000, 38,000 and 43,000 plants/acre),” explains Peter Thomison, Extension agronomist at Ohio State University. “A small but significantly higher yield (approximately 5 bu./acre) occurred when plant populations were increased above 28,000.”

Thomison says the Ohio findings were similar to research in other states where the yield advantage for twin rows was usually less than 3 bu./acre.

At Purdue University, Tony Vyn, Extension cropping systems agronomist, agrees that more producers seem to be interested in twin-row systems for both corn and soybeans than before.

“I think there’s a sense that if you have twin rows and canopy cover is achieved earlier, and if the individual plants are spaced farther apart from each other, it will automatically result in a yield increase,” he says.

But after researching twin rows for two years, Vyn says, “There’s no significant yield gains associated with twin rows in the hybrids we looked at in a population range of 28,000-43,000.”

However, he sometimes sees a little advantage – about 2 bu./acre – with higher plant populations above 40,000 for twins vs. single rows.

“The bigger question is not what’s the row width but rather what’s the optimum density,” Vyn points out. “I believe the impact of plant density on final yield is a much bigger factor than the impact of row width on final yield. Getting plant density right makes more financial sense to pursue than changing from standard 30-in. rows to a twin-row system.” 

Dean Sponheim, a farmer from Nora Springs, IA, and sales rep for Pioneer, says he gets lots of questions from farmers interested in trying twin-row corn. So, his farm was used by Pioneer to cooperate in a large-scale trial looking at plant population and hybrid selection for twin rows.

“We tried nine different hybrids at three different plant population levels last year,” Sponheim says. “Only three showed yield advantages over 30 in. rows, but there wasn’t any correlation as to why. We even planted some at 50,000 seeds/acre and they yielded the same as in 30s.”

The test plots were planted in 30-in. rows with the twin rows 8 in. apart. “The twin rows stood better, but they didn’t yield more,” he says. This year, he’d like to get down to at least 6 in.

“This was our first year and I’m not going to give up on twins,” Sponheim says. “But I’m not going to make a wholesale change to twins like I thought I would. Still, I’m confident that twin rows are where we’re going to have to go.”

No Big Benefits From Twin Rows

Mark Jeschke, agronomy research manager at Pioneer, oversaw an extensive twin-row project last year that included 31 locations across the Corn Belt. When all the analysis was complete, on average they did not see anything that suggests a broad advantage of twin rows over 30-in. rows.

“We tried to look at whether any particular environments or hybrids showed a differentiation between the two (twins vs. 30s), but we really didn’t see any,” Jeschke reports. “I wasn’t real surprised, though, because we’ve looked at narrow rows before and haven’t seen a consistent yield benefit across the central Corn Belt.” 

There might be more yield advantages in northern states based on other narrow-row research, Jeschke reports, but testing in those states was limited in last year’s study. 

January 2011