Casey, Ill., farmer Tony Baird and his grandfather Lee Ryan planted a quarter of their soybeans in 30-inch rows ahead of corn in 2020. Then after they were done with corn, they planted the rest of their soybeans in 15-inch rows.

University of Illinois trial data shows narrow rows average a couple of more bushels per acre, but Baird says, “Our data shows one year, 15-inch rows will do great; other years, 30s win out.” For the first time in at least seven years, the farm started using wide rows again in 2020 to increase efficiency.

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The results of 40 U of I trials confirm narrow rows yield better about half of the time, which may not be worth it on operations like Baird’s; he has one planter to cover 2,200 acres of corn and soybeans. He uses a 24-row split-row planter.

“We had all of the 15-inch bean units deactivated and raised up already at the beginning of the growing season. We found switching from beans to corn was much easier if we just kept it at 30-inch; then we could just put the corn plates on and go,” Baird says. They opted to plant some soybeans first instead of corn in 2020 because it was too wet to plant corn on their first day of planting, April 20.

Rather than reach for a marginal yield bump with 100% narrow-row soybeans like they have for the past seven years, Baird and his grandfather say they used their time more wisely on their planter and spread their risks with 30-inch-row soybeans at the beginning of the growing season.

By early May, they were planting corn. When they were done with corn, they switched the planter to 15-inch rows for later-maturing soybeans.

“Once we were done cleaning corn, it wasn’t a big deal to switch everything over to 15-inch rows. Plus, you’re helping shroud out weed pressure, so you might as well,” Baird says. “Switching back and forth in the early planting season is a lot to do when we have limited time.”

He’s satisfied with his wide-row soybean yields; they were 7.5 bushels better than the soybeans he planted later in 15-inch rows.

Route 16 and early soybeans

Baird’s and his grandparents’ Casey farm sits south of an old glacial border between southern and central Illinois. This border happens to align roughly with Route 16.

Pioneer agronomist Matt Montgomery says Route 16 is the dividing line for whether a farmer should use narrow-row soybeans or not: Below the line, benefits of using narrow rows usually increase and add a consistent yield advantage. Above that border though, it’s hit and miss.

“As you close in on Route 16 and the more variable soil conditions in southern Illinois, narrow-row soybeans have become pretty popular,” Montgomery says. “Part of that is weed management. Also, part of the secret for managing variable ground is to get a canopy over it very rapidly to help maintain an adequate moisture supply."

As soil types vary with low organic matter and shallow topsoil, he says, “then we probably need to think about adopting narrow rows."

In narrow-row trials in Champaign, U of I plant physiologist Fred Below found a 3.4-bushel yield advantage to 20-inch soybeans in 2020. While the plot sustained significant hail damage, which affects narrow rows more severely, the narrow-row soybeans still outyielded the wide rows, Below says.

A southern Illinois site in Nashville had a 5-bushel advantage for narrow rows. However, a northern Illinois site in Yorkville reported a 0.7-bushel loss with narrow-row soybeans.

“This tracks with what we’ve seen in corn too, which makes sense. Both crops are dealing with the same environment,” Below concludes.