Magnesium Sulfate

About This Product

Magnesium sulfate has the formula MgSO4 and is traded in several hydration states: the heptahydrate, CAS 10034-99-8, known as Epsom salt; the monohydrate, kieserite; and the anhydrous form, CAS 7487-88-9. All are white crystalline solids, freely soluble in water. Hydration state is the specification that matters commercially, because the water of crystallisation is inert weight. The heptahydrate carries seven water molecules per magnesium and is therefore only about 9.8 percent magnesium, while the monohydrate is around 17 percent and the anhydrous form higher still. Buying on price per tonne without reference to hydration is a common error, since the heptahydrate can look cheap and deliver far less nutrient. The heptahydrate dissolves faster and is preferred for fertigation and foliar sprays; the monohydrate is more economic to freight and suits soil application. Agronomically it supplies both magnesium, which sits at the centre of the chlorophyll molecule, and sulphur, in immediately available sulfate form. It is also used to control magnesium hardness in brewing liquor and as a set retarder and drying agent. It is used in fertilisers and foliar feeds, animal feed, brewing liquor treatment, bath salts, textile processing and as a drying agent. Bio Green Chem supplies magnesium sulfate to specification on hydration state, magnesium and sulphur content, chloride, insolubles, heavy metals and particle size.