It's a fact. Thirty-inch beans haven't been able to keep pace with the yields from beans planted in 15" rows. Twin rows, however, tend to make up the difference.
“It's basically a modified 15"-row system that you can drive down,” says Larry Elder, Exeter, Ontario (geographically similar to northern Iowa). “You get more air circulation when you plant double rows, increase your population and it's also a lot nicer to harvest.”
Twin-row beans were more of an accident than a plan for Roy Bloomfield, Ilderton, Ontario.
“We had been drilling beans in 15" rows, then bought a White central-fill, no-till air planter that gives us the flexibility to plant corn in 30" rows, soybeans in twin rows that are 20" apart, and wheat in 10" rows,” Bloomfield says. “I doubt I'd buy a machine just so I could plant in twin rows, but this planter has worked well for us from a machinery efficiency standpoint.”
Bloomfield uses just the front bar of the planter as a 6-row, 30" corn planter. For twin-row soybeans he locks up the front units and attaches the second toolbar that has row units 20" apart, on 30" centers. Using both bars gives him 10" spacings for wheat.
Elder uses a spring strip-till system to plant his twin-row beans in a corn-edible beans-wheat-soybean rotation. “I like to make my strips in the spring so I can plant into a fresh seedbed. After the soil dries a little, I come back with a Brillion packer,” he says.
“The packer flattens old corn stocks so the drill works better. It pushes down stones, breaks up clods and leaves a finer-textured soil so the drill throws less dirt. Perhaps, most importantly, it also extends the optimum time for planting. It gives me a longer planting window without worrying about the ground drying out,” Elder says.
Before zone-tilling twin rows, Elder had planted beans in 30" rows under conventional tillage. “I wanted to reduce labor and equipment,” he says. “When I switched, I was hoping for no net loss on yield. But now we definitely see a yield boost with the twin rows. Most data shows we should expect at least a 3-bu/acre improvement over wide rows.”
Elder also sees better yields with zone-till versus no-till. “There are some years, depending on weather, that we'll plant beans both ways,” he says. “Zone-till beans are noticeably better, especially in less-than-ideal conditions. With zone tillage, compaction is minimal because there's no wheel traffic on the row.”
Part of that improvement likely comes from the fertilizer Elder knifes in under the row when he creates strips. He pumps 12-15 gallons of blended 10-34-0 and 28% liquid fertilizer 6" deep. “I know soybeans don't need a lot of fertilizer, but I like to insure a good start without giving too much and making them lazy about nutrient fixing later on,” he says.
Bloomfield, on the other hand, hasn't necessarily seen yield increases with twin-row beans. “We've been able to maintain yields from the high 40s to low 50s, which is what we were getting with narrow-row soybeans under conventional tillage,” he says. “I wasn't sure what would happen when we switched from conventional tillage and a drill to no-till beans planted in twin rows.”
Bloomfield sees plenty of other advantages to the system. “The planting pattern creates a natural tram line that works out nicely,” he says. “We can go back in and spray post-emerge herbicides without running over any beans. At harvest, the snouts of the flex head skim right down the row without knocking beans over.
“One thing I noticed right away with twin rows is they bush quickly and form a canopy within a few weeks after planting,” he says. “I think it's important that farmers considering twin rows look for beans that like wider rows.”
The twin-row concept hasn't exactly swept across Ontario, according to Greg Stewart, corn specialist at the Ontario Ministry of Agriculture and Food (OMAF). He's been researching twin-row corn and soybeans.
“Probably less than 1% of our growers are using twin rows at this point,” he says. “The guys trying twin-row beans are essentially innovators who want to put beans into a system for strip-till. It's really the only way to make beans work in a strip-till system. Single-row beans in strip-till lose yield, but twins make it back.
“Most guys went to strip-till for corn and want to figure out a way to make it work for soybeans as well,” Stewart says.
Disease control and fertilizer efficiency also are reasons to consider twin-row beans, he adds. “White mold is a problem in narrow rows, particularly with farmers who grow dry beans as well as soybeans,” he says. “The white mold pressure comes off with wider rows where you get more air flow within the canopy.”
Like Elder, Stewart believes there is potential in knifing fertilizer beneath twin-row beans. “That's a real advantage — if we can show a fertilizer response,” he says. “You're creating a zone of loosened, highly fertile soil that the roots have direct access to. That's better than trying to increase fertility with dry broadcast fertilizer.”
Stewart also cites University of Guelph research showing that twin-rows consistently out-yield 30" beans in tillage and no-till conditions (see chart). Twin-row yields fall a bushel or two shy of yields from 15" beans under the same conditions.
“Twin-row beans haven't shown enough yield potential to justify the switch by itself,” he says. “But when you take a systems approach and spread the cost of twin-row planting over several crops, the benefits should offset the additional equipment costs.”