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Corn+Soybean Digest

Planting Corn and Soybeans In Twin Rows Offers Efficiency

With 15% higher corn and 10% higher soybean yields, Stan Flowers is doubly happy about twin-row crop production.

Zack Tanner also did a double-take when he saw the uniformity of seed depth provided by his twin-row planter.

Both growers farm in southeast Missouri near Dexter. They use twin-row planters manufactured by Monosem. Great Plains Manufacturing also is seeing growers benefit from its twin-row system, as farmers look for ways to efficiently improve performance.

Growers boast of better plant emergence due to more growing room from wider seed spacing. Researchers also see twin rows as a solid alternative to conventional 38-in., 30-in. and narrow-row corn and soybean production.

IN A TYPICAL twin-row system, crops are planted with a staggered seed drop. That allows for more growing room and quicker canopy than in single-row systems.

Twin rows are typically planted 7½-8 in. apart on 30-, 38- or 40-in. centers. Corn seed spacing is much wider. For example, in a 28,000-plant population in corn, twin rows will see 12-15-in. spacing, compared to about 7½ in. for a single 30-in.-row crop. For a 38,000-plant population, spacing would be about 11 in. with a twin-row system and 5½ in. for single 30-in. rows. Seeds are usually in a triangle pattern.

“I had planted all our soybeans with a John Deere air drill,” says Tanner, who grows popcorn for his family's popcorn company, as well as beans and rice. “The disadvantage with the drill for soybeans is that we had uneven bed placement and depth.

“We added the twin-row planter for 2008 and got the best of both worlds. The seed is spaced uniformly and at a constant depth,” he points out.

His irrigated soybeans are seeded at a plant population between 140,000 and 150,000 seeds/acre. They are planted 2 in. apart. He was most impressed with the quicker and larger canopy twin-row beans established with the staggered seed placement. Yields are in the 65-bu. range.

Flowers grew to appreciate his twin-row system the first year he had it. That appreciation has grown, especially since his bean yields have increased by 5-10% and his corn yields are up 15%.

He farms both irrigated and dryland corn and beans. His bean plant population is also 140,000-150,000, while his corn plant pop is 26,000-34,000, with the higher being in irrigated fields.

“Some growers push their corn seed rate over that,” he says. “But our planting rates are good for our clay loam soil.”

His corn yields had been in the 170-175-bu. range. But after going with the twin-row system, yields jumped substantially. “I have to attribute some of that to the twin-row planter,” says Flowers. “Our field-average yields are now over 200 bu., which we hadn't seen before.”

His soybean yields haven't improved as much, however. “Our average yields are 50-55 bu./acre — up to 10% higher than the beans we still drill,” he says. “But what we like the most is the uniform seed placement we see. We also get a better root structure.”

HARVESTTIME IS NO different with the twin-row production. “There's no trouble picking corn,” says Flowers. “We can still use a 30-in. corn header and our bean harvest is also efficient with the twin-rows.”

Various studies of twin-row vs. conventional 30-in. single-row planting have been conducted across the Corn Belt. Results show strong yields from twin-row, but not al-ways higher than single-row.

At Iowa State University's (ISU) Armstrong Research Farm, agronomists compared corn yields in the mid-2000s. And more twin- and narrow-row studies are on the horizon, says Clarke McGrath, ISU agronomist.

“Some of today's new hybrids might fit better into twin- or narrow-row production,” says McGrath. “As we jack up plant populations, it's always interesting to look at different row situations.”

For the ISU research in 2002-2004, a Deere 7000 planter was used for both the 30-in. single-row and twin-row, which saw corn planted 7.5 in. apart on 30-in. centers. Plant populations were 32,000 for each. McGrath says that in 2004, the twin-row corn yielded 234 bu., while the 30-in. rows yielded 231 bu.

That compared to a 10-bu. yield advantage for twin rows in 2002 and a 2-bu. advantage for single rows in 2003.

Peter Thomison, Ohio State University (OSU) agronomist, says twin-row corn may offer some agronomic and financial benefits that conventional and narrow-row systems don't provide.

“Twin rows got a fresh look when there was a resurgence of narrow rows in the mid-1990s,” he says. “There was this perception that narrow rows might have a lot more yield potential than conventional row spacings.”

OSU conducted a three-year study in the 1990s to determine the yield potential of twin-row corn production. The study, performed in southwest Ohio, compared the twin-row system to 30-in. conventional and 15-in. narrow-row configurations.

“It found that twin-row systems performed as well or better than the other production systems, with a yield advantage over the conventional system ranging from 4% to 15%,” says Thomison, noting that results of other university trials have been mixed.

“The boost in yields from twin-row and narrow-row systems may be due in part to a more rapid plant canopy development that translates into higher yield potential,” he says.

Growers with RTK auto-steer can easily make sidedress applications in a twin-row system, notes Tom Evans, a spokesman for Great Plains Manufacturing, which has several twin-row units on the market.

THE INCREASED SPACE between plants enables twin-row crops to use more of the available sunlight and promotes more root development. Better standability helps produce a stronger stalk, says Evans — one that has about 1⅛-in. diameter, compared to ⅞ in. for most 30-in. corn.

There can be disadvantages to the twins, though. Flowers saw one snag with the narrow width of the system. “The 22 in. between rows made it more difficult for tractors with 18.4-in. tires,” he says. “It was harder to get down the middle. We switched to a smaller tractor with 14.9-in. tires on it and our sprayer.”

Thomison says he expects that as seeding rates increase, more growers will look into twin-row production. “If a grower has high yields now and is growing high plant populations, twin-row production may be one approach he can take if he's looking for an alternate planting option,” he says.

He adds that more work is needed to determine the role of hybrid, seeding rate and production environment on twin-row corn yield potential, and universities are looking into these roles.

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