COLUMBUS, Ohio – Cool, wet, muddy conditions in May and drier soil conditions this month in much of Ohio that contributed to uneven soybean emergence doesn't necessarily mean that growers need to replant, says a field crops expert with Ohio State University's College of Food, Agricultural, and Environmental Sciences.
Unless growers with uneven soybean emergence can determine that their seedlings are dead, they may want to hold off on replanting decisions, said Laura Lindsey, a soybean and small grains specialist with the college's outreach arm, Ohio State University Extension.
Growers should start evaluating their soybean fields to see where they are at but should understand that there may be some emergence issues, Lindsey said.
"Planting conditions weren't ideal this year, and some soybean stands may not look good right now," she said. "But you have to keep in mind that while stands may not look so great right away and emergence is uneven, soybeans will even out in most situations."
Statewide, for the week ended June 1, soybeans were 66 percent planted and 31 percent emerged, according to the June 2 U.S. Department of Agriculture's crop progress report. That compares with soybeans at 86 percent planted at the same time last year, with 54 percent emerged during that same period.
Topsoil moisture in Ohio is 93 percent adequate to surplus, with subsoil moisture at 97 percent adequate to surplus, USDA said.
"While both corn and soybeans saw rapid emergence due to warm conditions, both are still behind the five-year average," the report said.
Growers whose plants aren't coming up should first try to diagnose why before making any replanting decisions, Lindsey said.
"When considering replanting soybeans, make sure to take into account the existing stand, yield loss due to late planting and the cost of additional seed," she said. "Soybean yield is decreased by approximately half a bushel per acre every day when planting later than mid-May."
Before growers consider replanting due to uneven stand, they should dig around in areas of their fields that have no plants. Growers who find healthy, germinated seeds that simply haven't broken through the soil yet can wait because the plants could still pop up with a little extra moisture, she said.
But growers who find dead seedlings or no seeds or seedlings should take a stand count to see how many plants are remaining, she said.
One way to estimate stand is to count the number of plants in 69.8 feet of row for a 7.5-inch row spacing. This represents one-thousandth of an acre, so 120 plants in 69.8 feet of row grown at a 7.5-inch row spacing represents a stand of 120,000 plants per acre.
"Soybean populations of 50,000 plants per acre yield approximately 15 percent lower than soybean populations of 116,000 plants per acre when planted in May, according to research by Ohio State's Agronomic Crops Team," she said. "But they still yield."
Estimates can also be done using 34.10 feet of row for a15-inch row spacing or 17.5 feet of row for a 30-inch row spacing, she said.