Question

Contains of a fertilizer

Answer 1

There are six primary nutrients that plants require. Plants get the first three—carbon, hydrogen and oxygen—from air and water. The other three are nitrogen, phosphorus and potassium.
the fertilizers mainly provide these 3 chemicals.
Example:
Sulphate of Potash
Sulphate of potash is the inorganic fertilizer which supplies the third-most needed nutrient, potassium, to the soil. Inorganic potassium fertilizers should only be used when there is an absolute potassium deficiency in the soil. Sulphate of potash is obtained by treating potassium chloride with magnesium sulphate. The resulting inorganic fertilizer is readily soluble in water and can be used in the soil at any time until sowing. Muriate of potash is another inorganic potassium fertilizer available in crystal form. However sulphate of potash is favored over muriate of potash by many gardeners.