Talk soybean population with Southerners and no consensus emerges. Some, like North Carolina State University Extension Specialist Jim Dunphy, say planting fewer soybeans per acre can mean greater profits. Others, like Louisiana State University’s (LSU) Ronnie Levy and Arkansas’ Jeremy Ross, recommend a higher rate. The answer could come down to individual management techniques.
Dunphy agrees that the issue tends to be contentious. “The right planting rate is up to the farmer because he’s insuring against replanting. So I don’t talk to them about planting rates. What I talk about is how many plants they need to end up with,” Dunphy says.
“In North Carolina full-season soybeans, 75,000 plants/acre is plenty. In double-crop beans, 100,000 may work best. With a 7.5-in. drill, 75,000 is one plant per foot. That will scare 99% of the farmers. But that soybean plant can compensate. We’ve been working with it 5,000 years. It has been through the hottest, coldest, driest and wettest and still survives. It’s an adjustable crop,” Dunphy says. “Don’t force ideas about other crops onto soybeans.
“Ten days of bad weather at the wrong time can wreck a corn crop. But a soybean plant will bounce back. You don’t often get less than half a soybean crop, but you sure do with corn, peanuts and cotton,” Dunphy says.
Brandon Hughes, who farms at Brownsville, TN, plants 150,000-160,000 seed/acre for his full-season soybeans and as many as 180,000 for soybeans double-cropped behind wheat. “We’ve had excessive rains the last several springs so I plant a few extra to account for loss,” he says.
A little farther north, at Chaffee, MO, Charles Hinkebein seeds 125,000/acre on his early soybeans, bumping to 135,000 later. “I’ve found that with treated seed with fungicide and insecticide on it, at that rate, I’ll be all right,” he says.
University of Arkansas ExtensionSoybean Specialist Jeremy Ross says research over the past decade shows that 120,000-130,000 soybean plants/acre gives optimal results in Arkansas.
“We’re working on a large seeding-rate project. It shows that if you plant more it may increase yield a little but not significantly, plus you’re increasing seed costs,” Ross says.
“There have been such problems with seed quality that I hate to see guys cut seeding rates back,” Ross says.
Go south and farmers see similar results. “We have a range of 80,000-120,000 plants/acre, depending on a lot of factors,” LSU’s Soybean Specialist Levy says. Planting late increases population because there is less time for growth, and they compensate with the number of plants. Under ideal conditions, the soybean plant can compensate with plant branching, and yields can be just as good with fewer plants,”
“There is work showing that 50,000-60,000/acre can make good yields under optimal conditions. But 120,000 is where we like to be,” Levy says.
In Mississippi, most soybean farmers in an early production system drop 120,000-140,000 seeds/acre assuming 80% emergence, says Tom Eubank, Extension agronomist. Technology has changed the philosophy, however.
“With the new precision planters, accuracy has gone way up in terms of how well we can place the seed in an even pattern. We used to plant 50-60 lbs./acre, regardless of seed size. Now we’re looking at individual seeds per acre. Decreasing population is not something Mississippi farmers are trying to do. Getting the majority planted by mid-May is how they’re optimizing yield,” Eubank says.
Hank Jones, a consultant at Pioneer, LA, recommends planting 140,000 seeds/acre. “That way, if you do lose some, you’ll still be fine. If there are issues with wet, cold weather and you wait to see if you got a good stand, you’ve wasted three weeks. If you plant more seed on the forefront, you’ll do fine,” he says. “On a 40-in. row, I want 10-11 seeds per foot of row. If you lose 10%, they’re still okay.”