Nitrogen, phosphorus and potassium usually come to mind first when growers think of critical nutrients for their corn or soybeans. But environmental changes in sulfur levels are causing growers to rethink their nutrient management plans.

For many years, growers benefited from sulfur deposits in the air and rain and weren’t too concerned about sulfur levels in their soil. However, due to clean air regulations in the past 25 years, the controlled air pollution and acid rain have unintentionally reduced atmospheric deposits of sulfur in crop fields. According to the National Atmospheric Deposition Program, atmospheric deposition of sulfur for crop use declined from 10-17 pounds/acre in 2000 to just 2-7 pounds/acre in 2015.

Another source of sulfur for crops is soil organic matter. While soil organic matter supplies approximately 30 pounds of nitrogen an acre per year, it delivers only 0.4-0.8 pounds of sulfur per acre each year.

With the drop in atmospheric sulfur deposits and the low amount of sulfur in soil organic matter, there is either not enough sulfur available for nutrient uptake or the sulfur is possibly lost to the environment as sulfate. This steady decline over the past two decades is leading farmers to consider investing in sulfur as part of their nutrient plan. 

FS Senior Agronomy Services Manager Dr. David Powell says it takes approximately 20 pounds of sulfur per acre to achieve a yield of 200 bushels of corn (0.1 pounds of sulfur per bushel). Soybeans require about 12 pounds of sulfur to reach 60 bushels (or 0.2 pounds per bushel).

“Given the tight margins growers face, every bushel counts. Growers need to get the most out of every acre. At FS, we’ve seen the important role sulfur plays in corn and soybean production. That’s why we have been testing the effect of sulfur on crops the past four years through our MiField Applied Research program,” Powell says.

MiField Applied Research trials indicated sulfur applied to corn and soybeans can have a positive effect on yield and ROI. In 2019, trials showed that corn acres treated with sulfur applications averaged 5.2 bushels per acre higher than acres without an application: slightly higher than the four-year average increase of 4.5 bushels per acre.

Using a sale price of $3.99 per bushel of corn, the 2019 net ROI for a sulfur application was an impressive $10.57 per acre. The three-year trial average for net ROI was $6.12 per acre.

In its second consecutive year, 29 MiField Applied Research trials on soybeans showed that a sulfur application of 22.7 pounds per acre increased soybean yields by an average of 2 bushels per acre. With a sale price of $9.07 a bushel, the net acre ROI was $3.70. The average of the two years of data shows even more impressive results, netting an increased ROI of $8.07 per acre.

“The results from these two years of trials on a sulfur application for soybeans are promising. We’re looking forward to continued testing so we can better understand the effects of rate, timing and products on soybean yield responses,” Powell says.

Given the depletion of sulfur, growers should evaluate this valuable nutrient as part of their plan. Learn more about these MiField sulfur trials or contact your local FS Crop Specialist and find out how sulfur can help boost your yield and ROI. If you want to see results from other MiField trials, download the complete 2019 MiField Trial Results.