It may appear as if we haven't made much progress lately in boosting U.S. soybean yields. But look further.
The national average yield record of 41.4 bu/acre was set in 1994 — nearly 10 years ago — and hasn't approached that level since. But we're actually doing better than it might appear in spite of this year's setback.
“In 2001, a year when soybeans faced many stresses and were not expected to yield well, we ended with the second highest national average in history, at 39.6 bu/acre,” points out Allen Dever of Doane's Agricultural Report. “That was despite the fact that we now have many more soybeans grown in outlying areas where yields are not as high as in traditional areas.”
Dever notes that there was a tight supply of Roundup Ready seed during the first several years the technology was available. And, he notes, some farmers settled for varieties with less-than-optimum yield. “That probably held down the national average yield for awhile.
“There's no doubt in my mind that soybean breeders have the genetic material, along with the advantages of biotechnology, to sustain a solid uptrend in bean yields.”
Soybean yields may appear to have plateaued on individual farms or in certain regions, which is usually due to non-genetic factors such as diseases, insects and weather, explains Monsanto soybean breeder Andy Nickell. Both diseases and insects are constantly evolving, so agronomists urge growers to stay on top of the changes and make the needed adjustments.
“A study of public varieties over the past 60 years by Jim Wilcox, retired USDA soybean breeder, shows there has been a steady improvement in yields and standability, particularly during the past 20 years,” Nickell notes. “This is especially true when you select the correct variety for the particular field.”
Nickell points out that yields have increased in spite of expanding challenges such as soybean cyst nematode, sudden death syndrome and soybean aphid.
The increase of soybean acres being grown over an ever-widening geographic area has been especially evident since Freedom to Farm legislation in 1996. “Take the Dakotas, for example,” Nickell notes. “They have seen a considerable increase in soybean acres, yet their weather is generally drier than in the Corn Belt and they face greater production risk because of that.”
Although Roundup Ready varieties, when first available, may have been somewhat lower yielding than conventional varieties. That is no longer true, says Nickell. “Just look at some of the state yield trials and yield contests for proof of their performance,” he notes. “A Roundup Ready variety won the Iowa Masters yield contest in 2001, and a Roundup variety also had the highest yield in Missouri that year. We've seen similar results in other states.”
Nickell sees future gains in both yield and disease resistance, especially from exotic germplasm. “We definitely are progressing in yield and other aspects of soybean genetics,” he says.