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In-Season Sulfur Application in Soybean

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Background and Objectives

 
  • Sulfur fertility has historically not been a major concern for growers on most soils; however, several factors have made sulfur deficiencies in crop production more common:
    • Increased removal due to higher crop yields
    • Increasing use of high analysis fertilizers without sulfur
    • Decreased manure applications in many areas
    • Reduced atmospheric deposition from industrial emission
  • A research trial was conducted at the Pioneer research farm in Johnston, IA in 2017 to evaluate the effect of in-season sulfur applications on soybean yield.:
    • Soil tests indicated low to medium sulfate levels in the trial field (9-14 ppm) and soil organic matter of 3.6%.
    • In-season applications were used to supply sulfur prior to and at the timing of peak plant uptake (Figure 1).
Graph showing sulfur uptake rate through the growing season for a 66 bu/acre soybean crop.

Figure 1. Sulfur uptake rate through the growing season for a 66 bu/acre soybean crop. Duration of peak uptake is represented by the horizontal black line (Gaspar and Conley, 2016).

Study Description


  • Location:
    Johnston, IA
  • Planting Date:
    May 12
  • Design:
    Randomized complete block, 4 replications
  • Soybean Variety¹:
    Pioneer® brand P31T11R
  • Treatments:
    Rates 0 lbs S/acre
    30 lbs S/acre    		 45 lbs S/acre
    60 lbs S/acre
    Timings June 14 (~27 days after emergence)
    July 12 (~55 days after emergence)
  • Sulfur was hand-applied as calcium sulfate (gypsum) 0-0-0-17.
  • Flowers and pods were counted five times throughout the growing season.
  • Tissue tests were taken 2 weeks after each S application.
  • Plots were machine-harvested for yield.

Results

 

  • Sulfur treatments showed no effect on soybean growth and yield in this study.
  • Yield did not significantly differ among sulfur application rates and timings (Figure 2).
  • Tissue test results showed no effects of sulfur treatment on leaf sulfur levels and were generally indicative of adequate sulfur fertility.
  • There were no differences in flower number, pod number, or leaf greenness among treatments.

    •  

    Chart showing the effect of sulfur application timing and rate on soybean yields.

    Figure 2. Effect of sulfur application timing and rate on soybean yields.

    Conclusions


    • There are several factors that have led to sulfur deficiencies in crop production being more common today than in the past.
    • However, results of this study are generally consistent with previous research conducted in Iowa, which has shown a relatively low likelihood of a yield response to applied sulfur in soybeans.

    Author: Samantha Reicks

    January 2018

    Gaspar, A. and S. Conley. 2017. Soybean Nitrogen and Sulfur Uptake, Partitioning, and Removal. Pioneer Research Update

    The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. 2017 data are based on average of all comparisons in one location through Nov. 1, 2017. Multi-year and multi-location is a better predictor of future performance. Do not use these or any other data from a limited number of trials as a significant factor in product selection. Product responses are variable and subject to a variety of environmental, disease, and pest pressures. Individual results may vary. Always follow grain marketing, stewardship practices and pesticide label directions. Varieties with the Glyphosate Tolerant trait (including those designated by the letter “R” in the product number) contain genes that confer tolerance to glyphosate herbicides. Glyphosate herbicides will kill crops that are not tolerant to glyphosate.

    Glyphosate Tolerant   Always follow grain marketing, stewardship practices and pesticide label directions. Varieties with the Glyphosate Tolerant trait (including those designated by the letter “R” in the product number) contain genes that confer tolerance to glyphosate herbicides. Glyphosate herbicides will kill crops that are not tolerant to glyphosate.

    ¹All Pioneer products are varieties unless designated with LL, in which case some are brands.