Soybean outlook & strategies
Like any farmer, soybean growers want to raise more to get ahead. Horst Bohner, soybean specialist with the Ontario Ministry of Agriculture, Food & Rural Affairs, said it’s possible to increase yields based upon past innovations, as no-till systems and Roundup Ready seeds fueled growth at a time when many farmers transitioned from dairying to field crops.
Bohner presented “The Future of Soybeans: Looking Back, Looking Forward – Best Management Practices for Modern Soybean Production” at the recent Soybean & Small Grains Congress, hosted by CCE’s Northwest New York Dairy, Livestock & Field Crops Program.
“We’ve come a long way in Ontario, maximizing our bushels,” Bohner said. “We think there’s opportunity in the North, the clay belt, that is largely unfarmed.”
The average in Ontario is 50 bushels/acre. Although cooler temperatures and poor drainage are challenges in the North, he believes that using better management practices will help increase yield.
Selecting higher yielding, better adapted varieties has helped boost yields since these became available, with an average annual gain since 1942 of 0.36 bushels/acre.
“Can we sustain soybean yields even though we’re growing in rotation corn, soy and wheat?” Bohner posed. “Especially in clay areas, they’re growing soy and wheat.”
He learned in school that if growers use only the same variety for 30 years, they should expect their yield to decrease. A study looking at 14 cultivars grown from 1993 to 2024 in Ottawa in a crop rotation resulted in an increase in yields.
Several components impact yield: plants/acre, pods/plant, seeds/pod and seed size, but Bohner said pods per plant is the most important factor.
The world record for soybean yield is 218 bushels/acre; the highest Ontario yield was 109 in 2023. Bohner said the shorter growing season represents a big factor in the North. That’s why he advocates for planting early – maybe even before corn – to obtain more nodes. He advised against frost seeding, as frost contributes to loss.
“Soybeans compete, so you need to thin stands, unlike corn,” Bohner said. “Seedcorn maggot can happen. That’s not great. You have to be willing to take a plant stand hit if you plant super early.”
Farmers should also be aware that especially with very early planting, residue is “the enemy of soybeans,” Bohner said. “If you get it out of the row, it’s fine.”
Another way to increase yield is to use the right genetics. “It doesn’t always make sense to plant long beans,” Bohner said.
He thinks the ideal planting date should be based upon the farm’s location as some long varieties won’t have enough time to mature.
Double cropping may also increase harvest. Bohner noted an experiment with a planting on May 20 for harvest on Oct. 1 compared with a second crop planted on July 11 with green on Oct. 1.
“Yield was incredible,” he said. “I’ve never seen anything like it. The shortest beans won. The seed quality was awesome. Don’t just plant a standard adaptive variety; figure out what works.”
The optimal seeding rate for double cropping was 263,000 seeds/acre with a July 11 planting date. This resulted in an expected yield of 42.8 bushels/acre with an expected gross profit of $480.38/acre.
“The future of soybeans is fewer plants per acre with more pods per plant,” Bohner said. “You have to understand your field.”
Overly tall, bushy plants may result in leggy plants and a canopy that encourages pathogen growth. Shorter plants will benefit the yield.
“With a good environment, you need fewer plants compared with a poor environment,” Bohner noted.
To improve soil fertility and increase the number of pods/plant, Bohner advised using fertilizer with phosphorus and potassium if a soil test indicates these are low. “They respond well to phosphorus, even if potassium is low,” he said.
In a “normal” field with good fertility, seed size matters most for better yield. “Studies show that if you take planting dates out, management practices only increase seed size, not pods per plant,” he noted.
Nitrogen is the best way to increase seed size, as it controls how much protein the seed can build. Using fertilizer with P and K can increase pods/plant and pod retention.
“If you’re low on phosphorus and potassium, the beans won’t mature correctly in fall,” Bohner said.
He added that biological nitrogen fixation problems are energetically costly to plants which may reduce yield potential, especially in high yield fields. Nodulation and nitrogen fixation are inhibited by cold soil temperatures, wet soils, dry conditions, soil pH, nutrient deficiencies, pests and available soil nitrate.
“Intensive management increases yield but is limited by irrigation,” Bohner said. “A lot of times when you see no response in soybean trials, moisture was a limiting factor.”
Bohner also said foliar fungicides, depending upon rainfall, can also increase seed size. “I’m a big fan of foliar fungicides in a high-yield environment,” he said.
Two passes can equal four to nine more bushels/acre under moderate white mold pressure.
Sulfur fertilizer can control how much protein the seed can build, which can make improve yield in sandy soil fields with low organic matter, especially when planted early with heavy crop residue.
“We’re not a big fan of elemental fertilizer,” Bohner said. “Apply spring or fall; it doesn’t matter. It’s just as likely to get a response. I like dry ammonium sulfate in spring.”
