Green up your lawn the Natural Way with Fast Acting Iron by EncapEncap Fast Acting Iron greens up your lawn while cutting down on maintenance. Encap Fast Acting Iron is a precise blend of iron, sulfur, and gypsum to work with the soil to build lush lawns without the excessive growth associated with nitrogen fertilizer. It’s a non-burning, non-staining formula, too. Encap Fast Acting Iron is the stain-free, stress-free way to a hardier, greener lawn. Helps green up lawns quickly.