By Scout Nelson
A study, funded by AFREC, is currently underway to understand the long-term effects of sulfur fertilizer applications on crop yield. The focus is on comparing elemental sulfur with sulfate sources in terms of their availability and effectiveness over time.
Background research indicates that while sulfur is predominantly found in organic forms in the soil, only sulfate forms are plant available. Sulfate, being negatively charged like nitrate, is considered highly leachable, yet studies have shown it can be utilized by crops years after application.
Elemental sulfur requires oxidation by soil microorganisms before becoming available to plants, a process influenced by soil conditions and the physical properties of the fertilizer.
The ongoing study began its first phase from 2019 to 2022 across four locations, with annual sulfur applications on a continuous corn rotation. Three sulfur sources were tested: potassium sulfate, K-MST, and Tiger 90, at varied application rates. The initial phase showed sulfur enhanced corn yield at three locations, with sulfate and MST sulfur outperforming Tiger 90 in certain instances.
Phase two, launched in spring 2023, continues the research at two locations. It involves splitting previously treated plots to compare the effects of continued sulfur application against the yield from residual sulfur from past applications.
The 2023 results showed that annual applications of sulfate and MST sulfur led to the highest corn grain yields. Interestingly, residual MST and Tiger 90, both elemental sulfur sources, produced similar yields to their annual applications, suggesting longer-term availability.
Tiger 90 indicated potential delayed availability, possibly due to less efficient oxidation compared to MST or sulfate sources.
Residual sulfate resulted in lower yields compared to its annual application, but higher application rates were more effective. These early findings hint at the potential need for varying application rates over time, depending on the sulfur source used.
This research, still in its early stages, is important in understanding how different sulfur fertilizers can benefit crop production in the long term, providing valuable insights for future agricultural practices.
Photo Credit: gettyimages-songdech17
Categories: Minnesota, Crops, Corn