How thick should you plant soybeans this spring? The high price of soybean seed makes this a key question as spring approaches. Lloyd Murdock, an agronomist formt eh University of Kentucky, told farmers in Ripley OCutny gathered for an annual No-Till breakfast that stands some consider thin are likely still adequate.
Murdock does most of his work at the Pricneton Research Center in western Kentucky. He says soils are somewhat similar to those in southern Indiana. The most recent data from soybean trials in his area indicate that 100,000 plants per acre in full-crop soybeans are sufficient. In fact, the researchers also found nearly the same yields at stands as low as 40,000 to 50,000 plants per acre. However, somewhat higher numbers would be required for best performance in doublecrop soybeans, the researcher notes.
"The key is that we're talking plants per acre," Murdock says. "You have to factor in what emergence percentage you expect." That can depend partially upon the planting equipment that you select.
Because 15-inch rows are generally planted with a planter, such as in split-row arrangements, he tends to prefer 15-inch rows. That provides for a better shot at emergence, he says.
He also notes that while there is a slight yield advantage for narrow rows in his area, the biggest share of it can be picked up moving from 30 to 15-inch rows, rather than all the way to 7 inch rows. That's one reason he prefers 15-inch rows.
Chris Linville, a Ripley County farmer and seed rep for Stewart Seeds, Greensburg, notes that planting fewer seeds and obtaining thinner stands works as long as the stand is uniform, and there aren't big gaps within the field. It's also important to talk about viable plants.
"If you have 100,000 healthy plants, that's one thing," he notes. "But if you have 80,000 healthy plants and 20,000 just hanging on, that's something else again."
Some farmers questioned whether adding seed treatments would allow you to plant fewer seeds per acre. Murdock noted that since he hadn't tested seed treatments directly, he didn't feel comfortable commenting on the question.
More seed treatments are appearing on the market. It's important to understand what ingredients each one contains before deciding if it's a good fit for your farm and planting system, other sources note.