New Illinois Sulfur Trials Planned For 2026

By Andi Anderson

The Illinois Soybean Association (ISA) On-Farm Trial Network (OFTN) is seeking cooperators for its 2026 Sulfur 2.0 action trial protocol to continue statewide research on sulfur management in soybeans. This new phase builds on strong participation in the 2025 trials, when more than 15 Illinois counties took part in the first sulfur protocol.

Responding to the annual Soybean Production Concerns Survey and grower feedback, ISA launched sulfur trials to examine the benefits of sulfur applications before planting soybeans. The 2025 program generated valuable management data, tissue samples, and observations. Yield results are being analyzed and will be shared soon on FieldAdvisor.org.

The 2026 Sulfur 2.0 trial is designed to expand participation and collect data across a wider range of Illinois environments, with special attention to early planting and no-till conditions. The goal is to measure the yield impact of sulfur fertilization and provide clear, research-based recommendations for soybean production.

According to the new protocol, cooperators will manage sulfur applications and field planting. Each trial site must cover at least 40 acres, with four replications of both sulfur-treated and control plots for a total of eight plots. Each plot must be at least 60 feet wide to ensure accurate comparisons.

Sulfur treatments will apply 30 pounds per acre of actual sulfur and must match the nitrogen rate in the control plots. Approved sulfur sources include:

• Ammonium Thiosulfate (ATS): 115 lb/A broadcast spray (10.4 gal/A) supplying 30 lb/A sulfur and 13.8 lb/A nitrogen.
• Ammonium Sulfate (AMS): 125 lb/A dry preplant application supplying 30 lb/A sulfur and 27.6 lb/A nitrogen.
• Gypsum: ~176 lb/A adjusted to grade, used only as an additional treatment along with ATS or AMS.

Applications can be preplant or applied as a starter using a sprayer, dry broadcast, or drone technology. Combines must be equipped with calibrated yield monitors to provide accurate harvest data for post-season analysis.

By expanding the sulfur research program, ISA aims to provide Illinois soybean producers with practical, science-based insights to improve fertilization strategies, enhance yields, and strengthen overall crop performance across the state.

Photo Credit:illinois-soybean-association