Fertilizers
Sulfur Fertilizers
Most sulfur-containing fertilizer materials generally can be divided into four groups: (1) fertilizers containing sulfate, (2) fertilizers containing elemental sulfur, (3) fertilizers containing a combination of sulfate and elemental sulfur, and (4) liquid sulfur fertilizers. Sulfate-containing fertilizers provide most of the fertilizer sulfur applied to soils. These materials have the advantages of supplying sulfur primarily as a component of multi-nutrient fertilizers in a form, sulfate (SO42¯), that is immediately available for plant uptake.
Ammonium Sulfate
Ammonium sulfate (AS) is one of the oldest of nitrogen and sulfur-containing fertilizers. The main advantages of ammonium sulfate are low hygroscopicity and chemical stability. Ammonium sulfate resists nitrogen loss naturally, without any need for inhibitors.
Ammonium Thiosulfate
Ammonium thiosulfate (ATS) is a clear liquid fertilizer that contains nitrogen and sulfur. ATS is 26 percent sulfur. Of that, 50 percent is elemental sulfur and 50 percent is sulfate sulfur. This is important because only sulfate is readily available to the plant. Elemental sulfur slowly converts to sulfate over time. This provides a very effective, slow-release capability. In addition to providing sulfur, ATS can also reduce ammonia volatilization by delaying urea hydrolysis.
Ammonium Phosphate Sulfate
The most common grade of ammonium phosphate sulfate has the analysis 16-20- 0-14S. It is composed of about 40 percent monoammonium phosphate and 60 percent ammonium sulfate. Other products of this type include 13-39-0-20S, 19-9-0-20S, and 23-20-0-7S.
Potassium Sulfate
Potassium sulfate is the major potash fertilizer containing sulfur. It is a material containing 42 to 44 percent potassium (50-53% K2O) and 17 percent sulfur. Although potassium sulfate can be costly in some markets, compared to potassium chloride, it remains a widely used specialty fertilizer for valuable cash crops such as potatoes and tobacco, which are sensitive to chloride.
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