Planting twin-row corn for silage requires extra effort and expense. But it's a paying proposition, say several Wisconsin growers and specialists who have tried it.

Donald Vine figures a gain of $3,000/year off 40 acres planted in twin rows vs. 30" single rows. Joe Kusilek uses the same planter for corn and soybeans by twin-row planting his 150 acres of corn while increasing plant populations and yield. And Ron Kutz saw an 8.5% silage yield increase using a higher population in twin rows over conventional 30" rows in a small experiment on his land.

Yet, says Joe Lauer, University of Wisconsin agronomist, twin-row yields were not consistently higher in studies where two rows planted 7½ or 8" apart on 30" centers were compared with 30"-row or 15-20" narrow-row plantings.

“Half of the time 30" rows will beat narrow or twin rows and the other half of the time twin or narrow rows will beat 30" rows. We can't make a recommendation because there's no consistent pattern when moving from 30" rows,” Lauer says. (For growers still planting 38" rows, moving to twin or narrow rows shows a definite yield increase of 6-8%, he adds.)

However, there is a machinery-related cost advantage to moving from 30" to twin rows, he says. “Growers can use one planter for many crops and don't have to change their equipment that much to do it. It's not so much due to the yield increase.” Yields may not increase or may offer only a 3-4% advantage when planting width changes from 30" to twin rows, studies have shown.

Some Wisconsin growers have seen real increases.

“We saw about 2 tons dry matter more per acre. We were running around 7 tons/acre and now we're at 8.7,” says Vine, who farms with his parents, Richard and Deborah, near Granton. The Vines upped their 35,000 plant population on 50 no-till acres of corn grown for silage to 40,000-45,000. They have planted twin rows for five years using a 30" single-row planter. “I plant it, turn around and plant it again. I just move over about 6",” Vine says.

This past season, Vine was amazed that the twin-row crop yield was maintained during a challenging harvest. “Our quality wasn't bad, either.”

Kusilek, of Baldwin, uses a White planter to create twin 7½” rows on 38" centers. “My corn planter is set up for 38" rows and I was going to go narrower but couldn't. I would have had to change the fertilizer boxes and it didn't look like that would work,” he says.

One advantage to twin rows is being able to plant soybeans and corn with the same equipment, Kusilek says. “The other thing I wanted to do was increase my population and this allowed me to do that.” He upped it from 28,000 to 32,000.

“It has paid quite well for us,” he says. Corn he grows for grain increased, on average, by 30 bu/acre. Silage yields depended on weather and growing conditions: this past season he realized just 12-13 tons/acre. The previous year was a good year, with yields at 20 tons/acre. In 2004, silage brought 16 tons/acre.

“I think there was a definite yield increase, but most was, as much as anything, because of the increase in population,” Kusilek says.

Growers should be careful to distinguish whether yields rise because of narrower- or twin-row spacings — or increased plant populations, agrees Lauer.

Ron Kutz, Jefferson, got into experimenting with twin rows this past year all because he was in the right place with the right relatives who had the right equipment. Custom planters Dennis and John Kutz, who farm at nearby Fort Atkinson, owned a 12-row Kinze planter set for 30“. When they added a Great Plains twin-row to their lineup, Jefferson County extension agent Tim Bender perked up his ears.

“When I found out John and Dennis bought this new planter,” Bender remembers, “it was very intriguing.” The twin-row and the 30"-row planters had the same row units, Keeton seed firmers and identical precision seed meters, Bender says. He'd been curious about studies on twin-row corn and asked the Kutz relatives if they'd be interested in a couple of experiments.

One tested twin rows for grain at Dennis and John's farm, where a triple-stacked corn hybrid was planted at four populations. The Great Plains machine, which plants two rows 8" apart on 30" centers, placed strips at 33,000, 36,000, 39,000 and 42,000 plants/acre. Next to each twin-row strip, strips of 30" single-row corn were planted at populations of 33,000.

Then, on Ron's dairy farm, nephew John planted a twin-row silage corn strip with the Great Plains planter. Next to it, a 30"-row strip was planted with the six-row John Deere planter Ron has been using for years. Both strips were planted at 32,000 plants/acre. Another set of strips was planted: the 30"-row was kept at a 32,000 population and the twin-row was increased to 38,000.

In both experiments, the middle six rows were harvested to avoid influence from the strips planted next to each other, Bender says.

The results? On the grain test, the 33,000 population surprised them all with the best yield: a $24/acre increase for twin-row over 30". The silage trial showed an increase of 800 lbs/acre more silage with twin-row over 30"-row at the 32,000 population — a 3% increase. At the 38,000 population, twin-row yield increased by 2,285 lbs/acre, or 8.5%, over the 30" yield.

“This is just based on total pounds (in the mid-60% moisture range). We didn't do any quality analysis on this silage,” Bender says.

The twin-row advantage intrigued the Kutz family as much as it did him, he adds. “They are quite encouraged and want to look at this with replicated strips this year.”

Silage Corn Planted Narrower Yields More

Converting from conventional to narrow-row silage corn can increase silage yields by up to 6.6%. Changing to twin-row brings a yield bump of 3%, according to Cornell University research.

Narrow and twin vs. conventional-row systems do cost more in equipment. And potential damage to corn — applying postemergence herbicides or sidedressing N in very wet springs — explains, in part, the limited adoption of narrow-row in that state, the study shows.

Yet some dairy farmers have considered converting from conventional to twin rows because twin rows are more compatible than narrow rows for applying herbicide on glyphosate-resistant corn.

“The use of glyphosate-resistant corn in twin rows may provide an advantage by delaying herbicide applications until mid-June, thereby increasing the probability of a timely first harvest of perennial forages,” according to the study. Called “Growth, Yield, Quality and Economics of Corn Silage under Different Row Spacings,” the study was authored by William Cox, a Cornell University crop scientist, and colleagues.

One dairy participating in the study later bought a Great Plains precision drill to plant twin-row corn, half of which was glyphosate-resistant in 2004. The other dairy in the study had adopted narrow-row silage corn in the mid-1990s. It kept its Kinze narrow-row planter and applied pre-emergence herbicides on all its 2004 silage corn.