Early soybeans can jump-start success in the Midsouth, where many growers now head to the field as soon as soils are warm enough to plant. They’re planting more Group IV varieties than ever, often in April. That lets them harvest early enough to avoid costly late-season stresses from diseases and pests.
Larry Heatherly, USDA-Agricultural Research Service agronomist emeritus at Stoneville, MS, provided much of the scientific basis for the current trend to earlier planting in the Midsouth.
“The (Mississippi) state yield was stuck at 20 or 21 bu., year after year. No matter what the plant breeders were doing, that was still the yield for the whole state. Growers were hitting severe heat and drought in July and August, which they needed to avoid. We were wasting about a month of growing season, early. All of April was just sitting there, waiting to be used,” Heatherly says.
“We started working on this in the mid-1980’s. There were no Group IV’s adapted to Mississippi. We brought in early varieties that had done well in South Texas. Grover Shannon, then a breeder with Delta and Pine Land Company, Scott, MS, realized this was worth pursuing. That’s when we started getting some Group IV’s that do well in the Delta’s clay soils,” says Heatherly, who now works for the Mississippi Soybean Promotion Board and is a University of Tennessee adjunct professor of crop science.
Heatherly thinks switching to earlier planting accounts for a lot of the Midsouth’s soybean improvement over the past decade or so. In 2010, Mississippi soybean yields averaged 38.5 bu./acre on 1.43 million acres. Compare that to 2000, when the state averaged 22 bu./acre on 1.58 million acres.
Over the past five years, 82% of Mississippi’s soybean crop has been planted by May 15, says Tom Eubank, Mississippi Extension agronomist. “That’s the way to maximize yield. Past May 15, yields with Group IV’s decline in Mississippi. If you do have a stand failure and find yourself replanting in late May, you’re behind the eight-ball,” Eubank says.
Neighboring states are planting earlier, as well. Most of Louisiana’s soybeans are now Group IV’s and V’s, and some Group III’s go in the ground where sugarcane follows the soybean crop, says Ronnie Levy, LSU AgCenter soybean specialist.
“We had been primarily growing Group VI’s and VII’s, but IV’s and V’s are better suited for Louisiana. We’ve seen yields as good or better than the later soybeans without the extra risk for diseases, worms and stink bugs that come with the later ones,” Levy says.
Ag consultant Hank Jones, in the northeast part of the state, says most of his customers grow Group IV’s ranging from 4.5 to 4.9. “They yield better and usually let growers take advantage of better weather for pod set. Then they come off in August and early September, which reduces risk,” says Jones, Pioneer, LA.
Some Arkansas growers now like Group IV’s. Others prefer somewhat later soybean varieties in order to avoid conflicts with corn and rice harvest.
“Everything has shifted a little earlier. Ten years ago, we had Group VI’s in the state. Now there are hardly any,” Ross says.
Tennesseans also moved to Group IV’s, but most plant in May rather than April, says Angela Thompson, Tennessee Extension corn and soybean specialist.
“The priority, if they grow cotton, is to get that cotton planted. Almost 80% of our soybeans are now Group IV’s. That’s a huge shift from five years ago. Growers like the Group IV’s indeterminate growth habit,” Thompson says.