a compound containing sulfur that is used as fertilizer. Potassium sulfate, magnesium sulfate, ammonium sulfate, phosphogypsum, and inorganic substances having a low sulfur content are used as fertilizers.
Sulfur fertilizers are effective for crucifs, legumes, and composites, all of which require rather large amounts of sulfur. They are also effective as indirect fertilizers: they partially neutralize soil alkalinity and increase the absorption capacity of low-solubility phosphates. Sulfur fertilizers are applied during autumn plowing or spring replowing; the amount is 30–50 kg SO3 per hectare.