Magnesium Sulfate (Epsom Salt) Plant Nutrients - 50 Pound Bag by Growers Solution Purchase a 50 pound bag of Magnesium Sulfate (Epsom Salt) OMIR Certified. Epsom Salt contains essential plant nutrients: magnesium and sulfur. An ideal source for all Fertigation Systems: center pivot, micro-jet, drip-trickle and foliar spray applications. Magnesium is an important co-factor in enzymatic reactions vital to every metabolic pathway in every animal species. Epson Salt is one of the most versatilel household products.