Jonathan Green Mag-I-Cal PlusNatural soil food for lawns in acidic soil Helps to rapidly raise soil pH increasing nutrient absorption Loosens hard soil promoting air and water penetration for better rooting Jonathan Greens Mag I Cal Plus for Lawns in Acidic & Hard Soil contains calcium carbonate in a completely soluble form that is immediately available to adjust soil pH upwards. Poor soil is often the problem in growing a great lawn and calcium is vital to many grass plant