Research Reveals Sulfur Timing And Soil Type Improve Crop Performance
Research led by Daniel Kaiser from the University of Minnesota Extension shows that sulfur management is more complex than many growers assume. Sulfate, the plant-available form of sulfur, does not always leave the soil quickly. Although it can leach due to its negative charge, the speed of loss depends largely on soil texture.
Medium and fine-textured soils often hold sulfur longer than expected, while sandy soils tend to lose nutrients faster. This difference highlights the importance of soil-based management decisions.
A long-term study in Minnesota examined sulfur carryover in continuous corn systems. Sulfur was applied for four consecutive years at rates of 5, 10, and 20 pounds per acre using both sulfate and elemental forms. After four years, some plots stopped receiving sulfur to measure how long the nutrient remained available.
Results from research sites at Rosemount and Waseca showed strong carryover effects. Applying 10 pounds of sulfate per acre for four years supplied enough sulfur for at least two additional seasons. However, lower rates resulted in small yield declines once applications stopped, indicating that crops still require a baseline sulfur supply.
The research also explains why earlier studies sometimes showed limited yield response to sulfur fertilizers. In many fields, sulfur had already accumulated from previous applications, providing enough nutrients for crops without additional fertilizer.
Soybeans require sulfur as well, but direct applications rarely increase yields. Across about 30 trials over 18 years, only two showed clear benefits. Instead, sulfur applied ahead of corn in a corn-soybean rotation often supports both crops through residual carryover. Applying about 20 pounds per acre can help corn first and later improve soybean growth.
Kaiser notes that fertilizer timing and source also matter. Crops such as corn, alfalfa, and canola respond strongly to sulfur. Fall applications may be effective on certain soils, but elemental sulfur products can take years to become fully available if mixed into soil too quickly. Adding sulfate sources or delaying incorporation may improve efficiency.
Overall, the research shows that proper sulfur management can support strong crop performance while reducing nutrient loss risks.
Photo Credit: gettyimages-eugenesergeev