Pay more attention to soybean varieties to gain as much as 20% in yield, according to Fred Below, professor of crop physiology at the University of Illinois. That’s the spread between the highest- and lowest-yielding varieties grown in the same location in the University of Illinois Variety Testing program.
Below proved this point in an eight-trial study conducted across Illinois to explore the impact of several “high-tech” management practices in soybeans, including seed treatments, foliar fungicides and insecticides, and a fertilizer package including micronutrients. In six of the trials, switching from “normal” to a fuller-season variety boosted yields by 3.2 bushels per acre, confirming the long-held wisdom that fuller-season varieties tend to outperform shorter-season ones.
However, in the other two trials, the fuller-season beans actually delivered lower yields. Below says the longer-season varieties in those two trials turned out to be poorly suited to the sites, illustrating the cost of making the wrong seed choice in intensive management programs.
Shaun Casteel, Purdue University Extension soybean agronomist, points out that top yield figures are just part of the equation.
“High yield is the foundation of variety selection, but high-yield potential doesn’t do you much good if the variety only performs well half the time,” he cautions. “Yield stability is the other part.”
Check variety trial data from several years, if available, and many locations to get a sense of a variety’s yield stability.