Shape up soybean yields
Farmers traditionally have gone gangbusters growing corn. Soybeans? Well, not so much.
Cory Atley has harvested bumper corn yields in recent years. In fact, he’s won the National Corn Growers Association (NCGA) corn yield contest for Ohio each of the past four years. He applies the strategy behind his corn yields – such as 2020’s conventional non-irrigated 320 bushels per acre – to soybeans.
It’s not easy. “Growing 100-bushel [per acre] soybeans is a lot harder than growing 300-bushel [per acre] corn,” he says. “There are a lot more people to network with in corn, lots more styles and strategies than there are with beans. There is also a lot more trial and error – a lot more failures to get to the point where you want to be.”
Here are some strategies he uses to aim for 100-bushel per acre soybeans.
Lower Seeding Rates
These new bean varieties don’t grow as a plant,” says the Cedarville, Ohio, farmer. “They grow like a bush. If you give them room, it’s amazing what they can do.”
Seeding rates between 60,000 and 120,000 plants per acre allow plants to pack on pods and maximize yields, Atley says.
Atley uses in-furrow fertilizer at planting which contains potash coupled with boron and MAP (monoammonium phosphate, 11-52-0). Applications of sulfur (S) also are key, as they consistently pay on low-organic-matter soils.
This coincides with Purdue University studies that show S applications spur soybean yields upward to 10- to 15-bushels-per-acre on sandy or coarse-texture soils with organic matter content below 2%.
Meanwhile, Purdue researchers have observed 4- to 6-bushel-per-acre responses on heavier soils with 2.5% to 3% organic matter.
“We’re trying to make the soybeans have enough nitrogen, and for nitrogen to work, you need sulfur, too,” Atley says.
Adequate fertility also enables plants to better withstand growing season stressors, whether they be weather, diseases, or insects.
“The biggest thing for us is keeping the plants clean and healthy,” he says. “Those plants are solar panels out there, soaking up the sun.” More sun generates more photosynthesis that ultimately leads to higher yields, he adds.
Foliar fertilizer applications are also tools farmers may use, says Jim McDermott, a DeKalb/Asgrow technical agronomist. Company trials in 2020 in Iowa and Illinois showed yield responses to foliar treatments of S, N, and potassium. “In environments where yields are already in the 60- to 70-bushel-per-acre range, foliar treatments have a better chance of a yield response,” he says.
Atley normally aims to plant soybeans in mid-April. “If conditions permit, we’ve gone in late March,” Atley says.
Cold and wet weather, though, is a constant threat to early-planted soybeans, especially those planted in late March.
“If I see the ground is just starting to warm up, but another cold snap is coming, I won’t plant,” he says. “If it’s going to be cold and stay cold, beans will be used to it.”
Warmer temperatures followed by a cold snap are another matter. “Beans then will be badly hurt,” Atley says. “It’s really a guessing game with the weather.”
Soybeans planted in mid-April through early May have ample time to harvest more sunlight and garner more photosynthesis that ultimately results in higher yields. Early planting also preserves yield potential that’s lost after a state’s recommended planting date. University of Wisconsin (U of W) researchers have observed yield losses of up to 0.5 bushels per acre per day after late April in Wisconsin, says Shawn Conley, a U of W Extension agronomist.
Early planting also works well with sulfur applications. Purdue studies have shown
double-digit increases in bushels per acre associated with planting in late April or early May. However, they do not occur on every field and in every situation, says Shaun Casteel, Purdue Extension agronomist.
One early planting drawback, though, is the incidence of disease such as Fusarium root rot and sudden death syndrome (SDS).
“They are more problematic in cool, wet springs,” says Dean Grossnickle, a Syngenta agronomic service representative. “A good seed treatment upfront will help prevent these diseases and preserve yield potential.”
"We’ve been fortunate in that we just have a couple fields in which waterhemp is coming in,” says Atley. “It came in a field of corn last year, so my dad, the guys from our farm, and I spent a lot of time in that field cutting it out with knives.”
To stop waterhemp in its tracks, Atley applies a preemergence residual herbicide ahead of planting. With early planting, though, this isn’t easy.
“You sometimes have to hold off with your residual because it can wear off by the time weed pressure comes,” Atley says.
Still, preemergence residual herbicides coupled with postemergence chemistry on herbicide-tolerant soybeans are an excellent one-two punch to control weeds, says Chris Doud, an area agronomist for Pioneer.
“We’ve become accustomed to the convenience of a postemergence trait, whether it’s for Roundup [glyphosate], Liberty [glufosinate], Enlist [2,4-D choline], or Xtend [dicamba],” he says. Still, Doud advises farmers not to let herbicide tolerance be the only factor in selecting soybean varieties.
“It’s an important aspect in the selection process, but yields and agronomics should be the most important factors in variety selection,” he says.
Cultural practices also are key. “Keeping equipment clean is also a step that we take,” says Atley. “To prevent outbreaks, blowing off equipment when moving between fields is a must.”
Drought cast a pall across much of the Midwest in 2020, just as it did during the last major drought in 2012.
On the plus side, advancements in breeding and technology enable farmers to better navigate adverse weather these days, says Cory Atley, who farms and owns the consulting company Advanced Yield LLC near Cedarville, Ohio.
“I remember what 2012 was like,” he says. “It was actually drier last year, though, in this area.”
However, yields were double digits higher in both corn and soybeans last year than in 2012.
Why the difference between 2012 and 2020?
“I just think the advanced technology and the breeding programs these companies have now have made it so we can still get these kinds of yields with just the little amount of rain we received,” Atley points out. “We get so much crop yield out of so little rainfall in years like 2020, compared with how it used to be just a few years ago.”