A few weeks ago, we had the pleasure of attending the Iowa Soybean Association’s On-Farm Network (OFN) conference in Ames. One of the highlights of the conference for me was the presentation by Dr. Tracy Blackmer about sulfur.
Sulfur application over the past 30 years was generally considered non-essential due to the high levels found in our atmosphere from power plant emissions high in sulfur, thereby satisfying plant needs. Times and emission standards have changed and, as a result, sulfur levels are much lower in atmosphere and soil than they were in 80s and 90s. Dr. Blackmer observed sulfur deficient corn in recent years and even dug out some old photos during his time at the University of Nebraska that showed sulfur deficiencies—at the time unnoticed, which was very surprising to him. Perhaps we have negated the benefits of sulfur application for far too long!
Gypsum (calcium sulfate) is a great source of sulfur and our gypsum product (SuperCal SO4) has been included in strip trials—on both corn and beans—within the OFN for the past few years. Some observations from aerial photography have shown strips that received gypsum are much darker green than those that didn’t. Looking further into the data, these same farms showed a corn yield increase from 0.5 to 8.8 bushel from sulfur application, as well as tissue testing that confirmed sulfur deficiency in the untreated strips. There is some thought that the sulfur being present in requisite amounts helps the plant use nitrogen more efficiently.
We look forward to further investigation of the benefits of sulfur application on corn in the upcoming season and beyond! Our thanks to all the cooperators within the OFN.