After hearing repeated farmer accounts of sulfur improving corn yields, Fabian Fernandez, researcher and assistant professor of soil fertility and plant nutrition at University of Illinois, decided to test response himself. His three years of research farm and on-farm trials seem to confirm the reports.

“We have seen an increase in the frequency and intensity of crop response to sulfur application compared to Illinois trials conducted in the late 1970s, which showed little to no response,” he reports. “The responses are very variable, but we are identifying conditions where sulfur applications will be beneficial for farmers.”

Results from a 2006 Iowa State University study on corn yield response to sulfur application showed an average 38-bu. yield response to sulfur application for six sites across northeast Iowa. These sites were specifically chosen for their likelihood of being sulfur deficient.1

In small research farm plots not specifically chosen for deficiency, Fernandez found a more moderate average 5-bu. corn yield response to sulfur applications over three years. One of his Illinois on-farm plots, though, yielded surprising results.

“It produced a one-year, 51-bu. corn increase over the check with an application of sulfur,” Fernandez says. “That’s not a normal response by a long shot, but it goes to show that if sulfur is truly deficient it can severely limit yields.”