Nutrient Management Tips: How Long Does Sulfur Stay In Your Soil?
Sulfur is a critical nutrient that plays a vital role in crop production. As atmospheric sources of sulfur have diminished in recent years due to improved pollution controls, farmers are focused on how they can effectively incorporate this macronutrient into their fertilizer management plans. As they consider their fertilizer options, growers may ask themselves, does the sulfur I apply in my fertilizer carry over from one year to the next?
Let’s dig into it. In an ongoing study performed by the University of Minnesota and funded by the Agricultural Fertilizer Research and Education Council, specialists analyzed how different forms of sulfur fertilizer behave over time. They analyzed sulfur from sulfate, MST (Micronized Sulfur Technology) and sulfur bentonite sources. While studies have shown that sulfate can be taken up by a crop over one year after application, this research was focused on exploring how long elemental sulfur fertilizers can supply plant available sulfur seasons after application (residual effect) through their impact on yield.
Results
Annual Application
During the first phase of the trial, the researchers found that annual applications of sulfate and MST have the greatest impact on crop yield. Crop yield was almost 20 bushels per acre higher in fields using MST or K-sulfate compared to fields using the other form of elemental sulfur. Crop yield was lowest in the untreated fields with an average of almost 140 bushels per acre—demonstrating the importance of sulfur in your nutrient management plan. The fields with the highest crop yield, using MST and K-Sulfate, had an average yield of almost 220 bushels per acre—showing the effectiveness of the technology in annual applications.
Residual Sulfur
In the fifth year of study the plots were divided, so half continued to receive sulfur fertilizer (annual), and the other half did not (residual). The results indicated that MST was the only sulfur fertilizer source that demonstrated carry over into while continuing to maximize yield—meaning it was the only sulfur source that could supply plant-available sulfur from one year to the next while maintaining a positive impact on crop yield.
Residual MST resulted in an average of almost 220 bushels per acre—the same yield that was seen during annual applications. In contrast, residual sulfur from K-Sulfate and the other form of elemental sulfur resulted in less than 200 bushels per acre in both trials and the untreated field produced less than 150. Applying MST annually maintains the level of sulfur nutrition needed, protecting the investment from leaching, and maximizing yields.
Release Rate Comparison
The study also found that the oxidation and availability of plant available sulfur is much higher in MST or sulfate fertilizer sources than traditional elemental sulfur forms. Traditional elemental sulfur can take months, or even years, to become plant available and results indicate its availability was minimal in the year it’s applied. When it does become plant available, it tends to supply less available sulfur than MST or sulfate fertilizer sources. MST addresses this issue with traditional elemental sulfur by providing quicker microbial oxidation—ensuring that plant-available sulfur is accessible in time to meet crop demand.
The Value of Micronized Sulfur Technology
While annual sulfur applications still have a greater impact on yield than residuals in the long term, the study indicates that Micronized Sulfur Technology can oxidize sufficient amounts of sulfur in the year of application, while contributing to soil sulfur levels for subsequent crops. These early research results point to the effectiveness of MST and its ability to supply sulfur for longer periods of time.
The results of this study also point to the advantages and benefits of applying sulfur in a modern cropping system. Untreated plots, without any added sulfur, produced the lowest yields in the trial with an average of less than 150 bushels per acre. Every other plot, regardless of the sulfur source, increased yield and produced at least 180 bushels per acre, even with residual applications. As growers strive for higher yields, selecting the appropriate sulfur source will be a critical component of their nutrient management programs.
While this study is still ongoing, the results help us to better understand how we can effectively incorporate sulfur into our nutrient management plans, how advancements in fertilizer technologies can positively impact profitability, yield and crop nutrition and the critical role that sulfur plays in crop production.
Interested in learning more about the value of MST and how Smart Nutrition MAP+MST can benefit your crops? Learn more today or contact your local rep for more details.
Sources:
https://blog-crop-news.extension.umn.edu/2023/11/sulfur-fertilizer-application-does-s.html
Additional Reading:
https://smartnutritionmst.com/news-insights/micronized-sulfur-technology-explained/
https://smartnutritionmst.com/news-insights/understanding-the-sulfur-cycle/
