Many southern soybean growers are switching to early maturing varieties to fool Mother Nature. That's nothing new to Rodger Allen. The East Texas producer has been swindling the old gal for some 20 years.
To help prevent late-season water damage and enhance his harvest schedules, Allen has been a big backer of planting maturity Group IIIs and IVs on his farm at Deport, TX, since the 1980s.
He plants about 600 acres of soybeans, 600 acres of corn and about 1,000 acres of cotton, his primary crop in most years. He staggers his harvests to be efficient. He can also escape late-August rains that often hit his region and reduce soybean quality.
“With Group IIIs and IVs we can normally harvest soybeans from Aug. 15-20,” says Allen. “That helps us get them out of the field before cotton harvest, which usually starts in mid-September.”
Until the 1980s, Allen was like most growers in his region. He planted Group VIs and VIIs up to June 1. “It was just common around here, so that was the plan we used,” he says.
But when some regional Extension service studies showed that the early maturing varieties would perform, he made the switch and hasn't looked back.
For 2006, Allen went with Group IV.3s to IV.7s. He planted his normal 40-in. rows. His “blacklands” soils range from a normal loam to gumbo clay. Using a John Deere vacuum planter, he puts out 120,000-130,000 seeds/acre. Only Roundup Ready varieties are planted in his minimum tillage operation.
By harvesting the early beans in August, he normally has plenty of time to come back with a winter wheat crop or get the land ready for cotton or corn to follow the next spring.
Which early soybeans and planting dates work best? Studies by Mississippi State University (MSU) at Stoneville in recent years looked at various Group III, IV and V varieties planted on March 13, April 2, April 23 and May 14.
MSU researchers found that the average flowering dates of Group III varieties were only 3-6 days earlier than Group IVs. However, they were 13-23 days earlier at maturity compared to Group Vs.
Time from emergence for Group IIIs and Group IVs across four planting dates were all less than 40 days, with some even less than 30 days. Average seed maturity time for Group IIIs was 2-3 weeks earlier than the Group IVs.
While the dodging of late-season rains is one reason for planting early varieties, MSU researchers say that in dry seasons, Group IIIs may avoid severe drought stress that can hurt late-maturing varieties.
However, with adequate rainfall or irrigation and when other environmental conditions are favorable for soybean growth, MSU claims early planting of Group IIIs may be a disadvantage, particularly if cool temperatures slow vegetative growth.
The overall studies showed that plantings before mid-April resulted in significantly shorter plants compared with the later plantings, MSU says. In addition, the number of main stem nodes was less affected by the planting date in most varieties, indicating that the process of internode elongation was more sensitive to short photoperiods.
Most of the early maturity soybean varieties in the MSU tests had an indeterminate growth habit allowing vegetative growth after flowering. Indeterminate soybean plants also fill pods set from the bottom of the stem up. Seeds from the bottom position in this case usually weigh more than those on the topmost part of the stem, the studies show.
The MSU studies back the notion that Group IIIs will work in the Delta region and other southern growing areas if the right planting time is used, probably more in early to mid-April than early March.
MSU says Group III varieties planted in March and early April resulted in early flowering, shorter plant height, lower flowering position of mature pods on the main stem, fewer pods per plant and the expected early maturity, all of which contributed to low yield.
However, within the optimum planting window, MSU studies show that acceptable yields were obtained for Group IIIs and the average yields were not much less than Group IVs and Group Vs.
MSU research also indicated that planting Group III varieties at the right time was more efficient than planting Group IVs and Vs varieties early to avoid midseason drought stress in summer.