Sulfur is an essential component of plant growth, with key processes relying on sulfur like chlorophyll formation and protein production. It is often considered the fourth major nutrient behind N, P and K. SO4 pelletized gypsum supplies a strong initial release of sulfur followed by a steady supply throughout the growing season, delivering the right of amount of sulfur to perfectly match plant needs for yield-maximizing plant growth. SO4 is mined and manufactured in northwest Iowa from one of the purest gypsum sources in the world. It is finely ground and pelletized to achieve a balance between solubility and pellet strength.