Clemson University agronomic crops researcher and assistant professor Pawel Wiatrak pushes his hat back a notch and in his best Polish-American Southern brogue puts his message in terms easily understood by the 200 or so farmers attending a field day at Florence, S.C.’s PeeDee Agricultural Research Center.

“Do you want to make more money growing soybeans,” he asks? “If so, I’ll tell you how you can do it.” And he does, offering growers research-proven, money-making seeding rate, timing of planting, and varietal information.

Statewide, South Carolina farmers averaged only 23 bushels of soybeans per acre last year — the lowest in the Southeast, and too low under any economic conditions, says Wiatrak. With beans consistently selling in the $10-13 per bushel range, low yields can cost growers real money, he says,   

“In South Carolina, Group V and VI varieties offer top yield performance when full-season planting occurs from May 1 until June 10. Hitting a 40-day window shouldn’t be too difficult, but getting the timing right is only part of the solution to low yields.”                  

Group VII and VIII varieties are recommended for later planting dates to allow adequate stem elongation prior to flowering. However, research has shown about a one-half bushel loss in yield potential for each day of planting delay after mid-June.                                                            

For growers who can’t hit the May-June best yield window of opportunity, Wiatrak says for soybeans planted after June 10, seeding in wider rows is a must to allow the crop time to lap the row middles. The 30-inch rows that produce top yields in earlier-planted beans won’t produce the same type yields in beans planted after June 10, he emphasizes.                              

For soybeans planted after June 10, seeding in row widths greater than 30 inches is discouraged because the crop is not likely to lap the row middles and produce yields equivalent to soybeans planted with a grain drill under a shortened growing period.

Regardless of row width, planting after July 1 will not allow adequate growth prior to flowering and yields will be greatly suppressed. Canopy development ceases near pod initiation and wide row soybeans fail to harvest sunlight from the row middles. The end result is reduced yield, he explains.                                             

After the June 10 deadline for planting, drilling beans into narrow rows has consistently produced a 10 percent to15 percent higher yield in research tests in South Carolina. 

Seeding rate is another key to higher soybean yields in the Deep South, he says. The old standard of planting pounds of seed per acre is a good recipe for reduced yields, he says.

“Seeding rates based on pounds per acre can cause an inadequate or excessive population. In addition, it may lead to an added expense, especially when using Roundup Ready varieties in which a technology fee is assessed to each bag of seed purchased.”