Give Beans Room To Breathe

Lower planting populations can make economic sense.

Stephen Ellis, Image by Mike Geissinger

There’s never been a better time to lower soybean seeding rates. Backed by genetic advances and modern seed treatments, Virginia farmer Stephen Ellis has been steadily thinning stands for years.

“We have never gotten low enough that it harmed us on yield,” he says. “That’s why I keep going lower.”

In 2017, Ellis averaged 120,000 seeds per acre in early-planted soybeans on the family’s row-crop operation, near Tappahannock. After experimenting with plots ranging from 240,000 to 30,000 seeds per acre, he aims to plant all his early beans at 90,000 to 100,000 seeds per acre in 2018. His goal is to harvest final stands of just 70,000 to 80,000 plants per acre.

Science is on his side, says University of Wisconsin small grains specialist Shawn Conley. “Soybean breeders have effectively cut the yield penalty for a thin stand in half,” he says.

Add protective seed treatments and early-planting efforts to the mix, and growers are perfectly positioned to push soybean yield potential higher than ever with fewer seeds than ever.

GENETIC GAINS. The soybean is already extremely adaptable, Conley notes. “The plants have an innate ability to branch. This allows plants to fill in gaps in the canopy and regain yield potential in thin stands.”

Ellis is accustomed to planting cutting-edge genetic packages each year. He grows many of his beans for seed production.

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Conley found big genetic strides in a study assessing germplasm from 1928 to 2012. “In low population environments, the modern soybean plants were able to put three times as much yield on those branches than they used to be [able to],” he says.

SEED TREATMENTS. Although he favored the 120,000-seed range this year, Ellis has long held that many growers in his region could drop as low as 90,000 without much yield penalty.

His on-farm plot experiments confirmed that theory this year. His best-yielding beans were planted at a modest 70,000 seeds per acre. These roomy plants were aggressively bushy and numerous enough to close the canopy quickly, which pushed their yield to 87 bushels per acre, Ellis says. His plots with 100,000 seeds per acre and 130,000 seeds per acre only yielded 82 bushels and 81 bushels, respectively.

PROFIT RATES. A recent economic study by Conley shows growers are most likely to make a profit in the current market with soybean rates ranging from 103,000 to 112,000 seeds per acre. Seed treatments are the key.

Ellis’s soybeans come to him fully packed with an insecticide, fungicide and inoculant. “If you plant that low, you’ve got to have everything on that seed, so you don’t lose any of that stand,” he says.

Early planting is the most reliable way to push soybean yields higher, Conley adds. Ellis actually finished planting his early soybeans on April 19 last year, a day before he wrapped up corn planting.

He credits that early planting date with his ability to maximize yield on thinner stands. Later-planted soybeans require heavier stands.

“We start at 120,000 and then add 20,000 per week starting around mid-May,” Ellis says. By the time his double-cropped beans go into the ground in mid-June, he’s planting 180,000 to 200,000 seeds per acre.

Narrow rows are also key for better managing thin stands, Conley says. Ellis drills 15-inch rows. “It just makes a bushier plant that sets more nodes--more places to set pods,” he says. Closing that canopy is also a weed-control tool.

Planting heavy soybean populations used to be a cheap insurance option. With pricey biotech seed, default-added seed treatments and low commodity prices, that mind-set no longer makes sense, Conley says.

Ellis estimates that if he had sown all his acres at just 70,000 seeds per acre this year, he could have saved $12 per acre in seed costs.

For More Information:

See Conley’s economic study on soybean seeding rates at bit.ly/2iJOYRV.

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