NPK 00:00:50, is a fertilizer that provides a high concentration of potassium (50%) along with sulfur (17.5%). It's a water-soluble fertilizer used  to  supplement potassium and sulfur in plants.

Magnesium sulfate (MgSO₄), commonly known as Epsom salt, is a white, crystalline salt that is readily soluble in water.It is a magnesium salt with sulfate as the counterion.

Ammonium sulfate, chemically represented as (NH4)2SO4, is a water-soluble inorganic salt primarily used as a fertilizer, particularly for alkaline soils.

Potassium schoenite is a natural, water-soluble fertilizer that provides plants with readily available potassium, magnesium, and sulfur. It's a double sulfate of potassium and magnesium, often used in agriculture to improve crop growth, yield, and quality.

Polysulphate 22:18:20 is a natural multi-nutrient fertilizer containing sulfur, potassium, magnesium, and calcium. It's a mined, crushed, and bagged fertilizer without chemical processing. The "22:18:20" likely refers to the percentages of the main nutrients: potassium (K), magnesium (Mg), and sulfur (S).