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Make Sulfur a Part of Your Nutrient Management Plan

Soils  show sulfur deficiency due to cleaner air and water 

When growers think of critical nutrients for their corn or soybeans, it’s usually nitrogen, phosphorus and potassium. But environmental changes in sulfur levels are causing growers to rethink their nutrient management plans.

For years, growers weren’t too concerned about sulfur levels in their soil. They benefited from sulfur deposits in the air and rain. However, clean air regulations over the past 25 years have unintentionally reduced atmospheric deposits of sulfur in crop fields by controlling air pollution and acid rain. 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.

Soil organic matter is another source of sulfur for crops. 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.

It takes approximately 20 pounds of sulfur an acre to achieve a yield of 200 bushels of corn (0.1 pound of sulfur per bushel), according to Mike Gill, lead crop nutrients technical manager for the FS System.  Soybeans require about 12 pounds of sulfur to reach 60 bushels (or 0.2 pounds per bushel).   

“Growers want to get the most out of every acre. So, every bushel counts given the tight margins they face. At FS, we recognize the importance sulfur plays in corn and soybean production. That’s why we have been testing the effect of sulfur on crops the past three years through our MiField Applied Research program,” Gill says.

MiField Applied Research trials indicated sulfur applied to corn and soybeans can have a positive effect on yield and ROI. In 51 trials last year, corn acres treated with sulfur applications averaged 5.3 bushels per acre higher than acres without an application. Trials the past three years showed sulfur applications increased yields an average of 4.6 bushels an acre.*

16-18 Corn Sulfur Yield.PNG

16-18 Corn Sulfur ROI.PNG

Using a sale price of $3.86 per bushel of corn, the 2018 net ROI for a sulfur application was an impressive $8.79 an acre. The three-year trial average for net ROI was $5.83 per acre.

2018 marked the first year for MiField Applied Research trials on sulfur applications for soybeans. The nine trials showed that a sulfur application of 22 pounds an acre increased soybean yields by an average of 3.8 bushels per acre. With a sale price of $9.40 a bushel, the net acre ROI was $22.15.*

2018 Soybean Sulfur Yield.PNG

2018 Soybean Sulfur ROI-1.PNG

“The results from our first year of trials on a sulfur application for soybeans are promising. And we’ll continue testing to better understand the effects of rate, timing and products on soybean yield responses,” says Gill

Given this depletion of sulfur, growers should evaluate sulfur as part of their nutrient plan. Contact your local FS Crop Specialist to learn more about adding sulfur to your plan to boost yield and ROI or visit fsmifieldappliedresearch.com.

* ROI is calculated upon a cost average of inputs of various sulfur forms and products with the corn sale price of $3.86/bu and soybean sale price of $9.40/bu.  Multi-year comparisons utilized the yield, sale price and cost average inputs for each respective year.  Application timing was not reported in these trials.

Photo: Sulfur-deficient soils may cause yellow-striping in corn. 

Make Sulfur a Part of Your Nutrient Management Plan

04/10/2019