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Corn+Soybean Digest

Twin Rows Help Boost Yields

Joe Sander doesn't mind seeing double when he gazes across his corn and soybean fields.

Farming has become, well, twice as fun for him after seeing the results of production under his twin-row cropping system on his Sikeston, MO, farm.

Twin-row farming on 30-in. centers enables him to produce up to 12 bu./acre more of soybeans and nearly 30 bu./acre more of corn. At prices over $11 for soybeans and above $3.50 for corn, that's close to $100/acre more for each crop grown under his twin-row program.

A six-row Monosem vacuum meter planter has made his double-cropped soybeans after wheat see the yield increases he was looking for in a new production system. Corn yields are also impressive to Sander, who uses a tractor-mounted planter as opposed to a pull-type unit.

“I wanted something that could help me increase my yields without having to add more acres,” says Sander. “I found it with the twin-row system.”

TWIN-ROW PRODUCTION has been looked at by many growers over the years. It has never taken off like traditional single 40-, 38-and 30-in. rows. But Andy Kleinschmidt, Ohio State University (OSU) Extension agronomist in Van Wert County, says tests comparing twin row to single 30-in. rows indicates the system can out-yield the single-row beans and produce comparable yields to ultra-narrow row and narrow systems.

He points out that 2006 tests showed twin-row beans with a 54.4-bu./acre yield, compared to about 56 bu. for 7.5-and 15-in. rows. The 30-in. rows in the test produced 50 bu./acre.

“Twin-row soybeans may be a viable option to narrower-row soybeans while allowing gaps to make late-season sprayer passes if needed,” he says.

Twin-row crops are planted with a staggered seed drop. The objective is to allow for more growing room and better canopy than standard rows. As a result of the twin-row configuration, plants and their roots spread over a larger area. Plants can catch more sunlight and nutrients.

For Sander, who also operates three poultry houses, the twin-row system has performed well in his sandy soil.

After trying ridge-till and later wearing out an old Buffalo planter with parts he says were no longer in production, Sander looked at a twin-row planter used and marketed by a friend, John Engram. The results were pleasing.

“For beans double-cropped after wheat, we used to see about a 40-43 bu./acre yield,” he says. “But in the twin-row system, we are seeing 50-52 bu. (up to 12 bu. more).”

Those beans are Group IVs planted around June 20 and harvested by Nov. 1. The twin rows are planted 7.5 in. apart on 30-in. centers; rows are about 23 in. apart. The seeding rate is about 171,000 seeds/acre and about 2.5 in. apart.

In early planted soybeans, Sander was looking at possible 70-80 bu. yields in late summer. “The twin rows really showed up strong again for me,” he says.

Gary Prill, OSU Extension agronomist who conducted the Ohio tests with Kleinschmidt, says the narrow-and ultra-narrow-row beans are more common in that state. “Most of the soybeans in our area are 7.5-or 15-in. rows,” he says. However, the twin-row production performed well and better than 30-in. beans. The twin row had a much lower seeding rate.

IN THE OHIO TESTS, the twin-row seeding rate was 190,000, compared to 185,000 for the 30-in. rows, 235,000 for the 7.5-in. and 210,000 for the 15-in., all in clay soil. They were planted May 31, 2006. The twin-row planter was a Great Plains Precision model 1525P.

Harvest was in mid-October 2006. Harvest plant population was 128,800 for the twin row, compared to 175,800 for the 7.5-in., 150,400 for 15-in. and 117,300 for the 30-in.

“There were statistical differences between the treatments for harvest populations,” says Prill. “You would expect some significant differences in harvest populations. Yields, however, were not statistically different for the 7.5-in., 15-in. and twin-row spacing, only the 30-in. row widths.”

Research through Mississippi State University indicates that in side-by-side comparative studies of 40-in. single-row soybeans vs. twin row (two 10-in. rows on 40-in. centers), twin rows produced 5 pods/plant more and higher yields than those in single rows.

Soybean yields totaled 80 bu./acre in the twin-row system compared to 73 bu. in the single-row system, marking an 8.5% increase in yield.

Twin rows work for corn, too. To help get the most out of his corn and soybean yields, Sander applies about 8 in. of irrigation water through center pivots.

Before adding the twin-row system, he averaged 168 bu./acre on corn. That has jumped to 190-194 bu. with twin row.

“Our corn yields have really improved with the twin row,” says Sander, noting that the cost of a little more seed per acre is certainly worth the added production that is coming from the new system.

SANDER PLANTS HIS corn in March. The twin rows are planted 7.5-in. apart at a rate of 36,000 seeds/acre. Seeds are spaced about 11.5 in. That compares to 30,000 seeds for the conventional 30-in. rows he used to plant. Those seeds were 7-8 in. apart.

“The twin row gives us uniform production,” he says. “The rows close up quicker to help with weed control. You can use the same corn header as you use for single row. You can also harvest soybeans the same as with single rows.”

Sander paid about $32,000 for his Monosem six-row twin unit. It features a 7 × 7-in. toolbar and 5 × 5-in. top bar, as well as fold-down markers for gauging accuracy in the field. Eight-row, 12-row or other units with many more extras would cost more, depending on a grower's specifications.

For more information on twin-row planters go to or to


While Ohio State University 2006 studies showed yield increases in twin rows when compared to 30-in. rows, studies through Iowa State University (ISU) indicate that yields are about the same when twin row is compared to 30-in. and 15-20-in. narrow-row crops.

ISU research in 2003-2005 shows no significant yield difference between a twin-row configuration and 30-in. row spacing during any of the three years, says Roger Elmore, ISU Extension corn specialist.

Also, in Wisconsin, twin row and 30-in. had comparable yields. In one test, twin-row corn with a 33,000-plant population yielded 228 bu./acre, compared to 223 bu. on 30-in. rows with the same planting rate. In another test, twin-row corn at a 36,000-planting rate yielded 207 bu., compared to 205 bu. for 30-in. at 33,000 plants.

One other test showed twin-row corn yielding about 209 bu. at a 39,000-plant population, with the 30-in. corn producing about 208 bu. with a 33,000 population.

Elmore says row widths continue to decrease for many growers. “Numerous advantages exist with narrow-row widths,” he says. “These include using the same planting equipment for corn and soybeans, reduced weed competition, increased shading of the soil, increased light interception per plant and less in-row crowding.”

However, Elmore says, “It's important to note that yields will not be reduced when using narrow-row widths.” Year-to-year response varied in ISU tests from 1995 to 2000, butin general, corn planted in twin and 15-in. rows yielded the same as 30-in. corn.

“Most farmer comparisons are not replicated and randomized trials,” Elmore says, “and many other factors may be the real cause of yield differences.”

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