University of Illinois researchers say corn response to sulfur may be more common than in the past.

In 2009, University of Illinois soil fertility and plant nutrition specialist Fabian Fernandez began a study to evaluate the response of corn to sulfur. He discovered that while some locations showed no response to sulfur, some did. Locations that were more responsive showed yield increases ranging from a few bushels to more than 50 bushels per acre compared to the untreated check.

While 2010 yield data is not complete yet, Fernandez did see visual evidence that sulfur applications were achieving a response.

"Sulfur is a very important nutrient for corn production," Fernandez says. "Historically, routine sulfur application for corn has not been recommended in Illinois because earlier research showed no response to sulfur and because soil supply, manure applications and/or atmospheric deposition were sufficient to supply sulfur needs for this crop."

But times are changing. Soil sulfur levels or supply may be diminishing due to several factors.

"Strict air-pollution standards have cleaned the air of gaseous sulfur compounds resulting in less sulfur atmospheric deposition," he says. "In general, many agronomic inputs, such as fertilizers, insecticides and fungicides, are 'cleaner,' having less incidental sulfur in them.

"Also, fewer livestock operations across the state are leading to decreased manure applications, which further reduce the amount of sulfur being applied with this fertilizer source."

At the same time, less incidental sulfur is being applied or deposited, there is greater removal of sulfur by increasing crop yields, he adds.

Due to these factors, Fernandez believes there is a need to further investigate sulfur fertilization for corn in Illinois. This study will produce valuable information regarding the frequency of sulfur deficiency that growers can expect, and most important, identify the most likely regions or conditions under which sulfur deficiencies can occur.

To increase the usefulness of this project to farmers, Fernandez needs volunteers throughout the state who would like to participate in an on-farm research study to measure corn response to sulfur fertilization.

Fernandez said all soil types will be considered, but his team is especially interested in light-colored soils (less than 2% organic matter, coarse texture or both) and soils with an eroded phase. The only soils that will not be considered are soils that have received manure or sulfur applications within the past 5 years.

Volunteers conducting these trials will follow a simple design applying 0 and 30 pounds of sulfur per acre as a broadcast application in a uniform portion of the field. A minimum of three replications or as many as eight replications are needed for each field. It will be important to geo-reference or clearly mark each strip with different color flags or markers in the center of each strip, Fernandez says.

Strips can be eight to 16 rows wide by 300 to 1,000 feet long. The size of the strip must allow accurate application of the rate, accurate measurement of yield, and if possible, be wider than the harvest strip. However, if the combine is at least 12 to 16 rows wide, it is possible to harvest the strip without having border rows.

Illinois researchers prefer the use of ammonium sulfate (NH4)2SO4 (21-0-0-24); MicroEssentials sulfur (ME S) ME S15 (13-33-0-15); or elemental sulfur (0-0-0-90). If the sulfur source contains other accompanying nutrients, the corresponding rates of those nutrients will need to be applied to other treatment strips to avoid a differential response to nutrients other than sulfur.

"Applying treatments this fall would definitely be an option," he says. "However, our preferred application time is the spring (pre-plant), but we understand that fall might be the only option for some farmers."