Sulfur is an essential nutrient for plant growth, aiding in chlorophyll production, enzyme activation, and protein synthesis. Two commonly used sulfur-based fertilizers are Ammonium Sulfate (21-0-0-24S) and Ammonium Thiosulfate (12-0-0-26S). While both supply nitrogen and sulfur, they differ in availability, stability, and application methods.
This guide compares ammonium sulfate vs. ammonium thiosulfate, their benefits, drawbacks, and when to use each.
✔ Readily Available Sulfur: Sulfate form is immediately plant-accessible. ✔ Reduces Soil pH: Ideal for alkaline soils (pH >7.0). ✔ Less Risk of Leaching: Ammonium nitrogen is more stable in soil than nitrate forms. ✔ Versatile Application: Can be used as broadcast, side-dressing, or dissolved in water. ✔ Enhances Nitrogen Efficiency: Sulfur improves nitrogen uptake and protein synthesis.
❌ Acidifies Soil: Continuous use lowers soil pH, which may require lime applications in acidic soils. ❌ Low Nitrogen Content (21%) Compared to Urea (46-0-0). ❌ Salt Accumulation Risk: Overuse can cause salt buildup in poorly drained soils.
✔ Dual Sulfur Forms: Immediate sulfate availability + slow-release thiosulfate. ✔ Liquid Form: Ideal for fertigation, drip irrigation, and foliar applications. ✔ Reduces Sulfur Deficiency Over Time: Provides a steady sulfur supply. ✔ Less Immediate Acidification: Slower breakdown minimizes pH fluctuations.
❌ Not as Immediately Available as Ammonium Sulfate: Thiosulfate requires microbial conversion to sulfate. ❌ Incompatible with Certain Fertilizers: Reacts with calcium-based fertilizers, leading to precipitation issues. ❌ Higher Cost Per Unit of Nitrogen: Less nitrogen per gallon than ammonium sulfate.
❌ Not Ideal for Dry Application: Liquid form limits storage and handling options.
| Feature | Ammonium Sulfate (21-0-0-24S) | Ammonium Thiosulfate (12-0-0-26S) |
|---|---|---|
| Nitrogen Content | 21% | 12% |
| Sulfur Content | 24% (all sulfate form) | 26% (mix of sulfate & thiosulfate) |
| Nutrient Availability | Immediate sulfur release | Slow sulfur release (thiosulfate conversion required) |
| Application Method | Dry, broadcast, or dissolved | Liquid, fertigation, or foliar feeding |
| Soil Acidification | Strong acidification effect | Less immediate acidification |
| Leaching Risk | Lower (ammonium N form) | Moderate (liquid form moves easily) |
| Best Use Cases | General field applications, sulfur-deficient soils, alkaline soils | Precision application, drip irrigation, foliar feeding |
✅ You need immediate sulfur and nitrogen availability.
✅ Your soil is alkaline and requires pH reduction.
✅ You prefer a granular fertilizer with easy storage and handling.
✅ You are applying broadcast or banded fertilizers in field crops.
✅ You need a slow-release sulfur source.
✅ You are using fertigation or foliar feeding methods.
✅ You want less immediate soil acidification.
✅ You are growing crops that require controlled sulfur release over time.
Both ammonium sulfate and ammonium thiosulfate provide nitrogen and sulfur, but they serve different purposes. Ammonium sulfate is best for fast nutrient availability, while ammonium thiosulfate offers a slower, sustained sulfur release.
✔ Choose ammonium sulfate for rapid sulfur uptake, alkaline soils, and field applications.
✔ Choose ammonium thiosulfate for fertigation, controlled sulfur release, and foliar applications.
✔ Soil conditions, crop type, and application method should guide your choice.
There’s a point in the season where adding more fertilizer stops being the solution. April tends to bring that into focus early. Fields are planted
Spring rain rarely arrives in a way that lines up perfectly with fertilizer plans. Some fields get just enough moisture to move nutrients into the
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