To get the best return-on-investment from your nitrogen (N) applications in corn pair them with sulfur, advises the agronomy team at Agri-Gold.
“Every time you put nitrogen out, whether it be on the planter, in a 2"x 2" situation or side-dressing liquid, putting sulfur in with that program is typically beneficial – especially when you're looking for higher yield situations,” says Kevin Gale, AgriGold agronomist, based in northern Illinois.
Sulfur is a useful partner in that it helps the corn crop metabolize N more efficiently, he adds.
Along with that, sulfur helps produce protein molecules and amino acids, which are required to produce chlorophyll, lignin and pectin. To do that, sulfur assists in photosynthesis, the process by which plants convert sunlight into chemical energy.
The AgriGold agronomic team addressed corn’s use of sulfur during the company’s annual Specialty Products Conference on Thursday.
Too cold, too wet. Stressful conditions early this season negatively affected sulfur availability in some northern Illinois corn crops.
“We've seen quite a bit of sulfur deficiency this year, especially in no-till or heavy residue situations,” Gale says. “A lot of it has to be attributed to slow mineralization, especially during the cool, wet conditions we had in May.”
In fields with high organic matter, Gale says soils typically release sulfur as temperatures increase and corn roots expand.
However, sulfur can be leached from soils by water, just like nitrogen. Also, in flooded fields that remain waterlogged for multiple days, sulfur will often volatilize and be lost as a gas.
Lighter, sandy soils with less water holding capacity are particularly prone to losing sulfur from leaching.
In all these scenarios, less sulfur availability to the plants can impact corn performance.
Sidedress applications can help. On lighter soils in Indiana, farmers are increasingly using a two-pass fertility program that includes sulfur, says Joe Steffan, AgriGold agronomist.
“At this point in the season, guys are putting sulfur on with their sidedress bar or Y-Drops,” he says.
Farm Journal Field Agronomist Ken Ferrie says to make sure to maintain the proper ratio between nitrogen and sulfur.
"Corn needs about 1 lb. of available sulfur per 14 lb. of available nitrogen," says Ferrie, who’s based in central Illinois, near Heyworth.
AgriGold Agronomist Josh Johnston says the farmers he works with in the South often use a higher ratio because they have little soil organic matter, commonly below 2%.
“For (most yield goals), we’ll use a ratio of 1 lb. of sulfur to 10 lb. of nitrogen,” Johnston says. “In high-yield conditions, for every 6 lb. of nitrogen we’ll use 1 lb. of sulfur.”
He adds that southern farmers routinely include sulfur in their corn fertility program.
Tissue samples can help you decide whether your sulfur level in corn is adequate. How you collect samples is important to the quality of the results you can expect from the tests, Ferrie says.
"Before you head to the field, check the sampling protocol by phoning your lab or visiting their website," he advises.