Sulfur placements’ impacts on corn hybrids grown in a two-year corn-soybean rotation

Study author(s): Daniel Kaiser, University of Minnesota
Growing season(s): 2022, 2023, 2024, 2025
Minnesota location(s): Rosemount, Waseca, Lamberton, Rochester

Note: All tables and figures can be downloaded in the below reports.

2025 Growing Season2024 Growing Season2023 Growing Season2022 Growing Season

WHAT IS THIS PROJECT ABOUT?

This four-year study focuses on how applying sulfur (S) affects long-season corn hybrids and the subsequent soybean crop in a two-year corn-soybean rotation. While sulfur is known to boost crop performance, farmers currently lack clear data comparing modern application methods—specifically banded vs. broadcast placement—and whether differing corn genetics change how much sulfur a crop actually needs.

The research is addressing three core problems:

  1. Placement Efficiency: Determining if subsurface band placement is more effective or efficient than traditional broadcast applications.
  2. Hybrid Genetics & Yellowing: Crop consultants report late-season upper-canopy yellowing in certain corn genetics. This study tests whether specific hybrids accumulate sulfur differently and if targeted sulfur applications can fix this yellowing.
  3. Long-Term Rotation Effects: Most previous sulfur studies lasted only a single year. This project looks at multi-year impacts to see how sulfur applied before corn carries over to benefit the following soybean crop.

KEY PROJECT GOALS & FARMER BENEFITS

  • Optimized Fertilizer Application: Identifies whether banding or broadcasting sulfur delivers better nutrient availability, potentially saving input costs.
  • Tailored Genetic Management: Clarifies whether you need to adjust sulfur rates or sources based on the specific corn hybrids you plant.
  • Tissue Test Reliability: Evaluates leaf tissue sulfur concentrations across different hybrids to see if standard tissue testing can reliably predict final crop yield.
  • Maximize Carryover Value: Tracks carryover benefits so you can understand the multi-year ROI of applying sulfur to corn and how it impacts yield, seed protein, and oil content in next year’s soybeans.

HOW THE STUDY WILL BE CONDUCTED

The research takes place across four Minnesota locations (Rosemount, Waseca, Lamberton, and Rochester) using a two-year corn-soybean rotation:

  • Sulfur Rates & Methods: All fertilizer is applied during the corn year using three sulfur rates (0, 18, and 36 lbs of S per acre). It compares broadcast ammonium sulfate (AMS) against subsurface banded ammonium thiosulfate (ATS) applied with the planter, with overall nitrogen levels balanced across plots.
  • Corn Hybrids: Two long-season hybrids (105-day relative maturity or greater) from Bayer and Corteva are tested side-by-side to measure genetic differences.
  • Soybean Rotation: In year two, soybeans are planted in the same plots without any additional fertilizer to measure carryover effects.
  • Data Collection: Researchers measure leaf tissue sulfur at key growth stages (V8–V10 and R1 in corn; R1–R2 in soybeans), harvest grain yields, analyze grain for protein, oil, and sulfur content, and perform post-harvest soil testing down to 24 inches.
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