Jonathan Green 54 lb. Mag-I-Cal Plus Soil Food for Acidic Soil. This natural soil food rapidly adjusts soil pH, helping to loosen heavy, hard-packed soils, feed and activate soil microbes, and maximize plant absorption of lawn food nutrients. Suitable for all grasses and can be used on lawns up to 15,000 sq. ft. Fortified with highly soluble calcium carbonate, fast-acting gypsum, humates, iron, and amino acids, it corrects acidic soil and promotes healthy growth. Safe to apply when seeding or sodding, best applied during the growing season when the soil is not frozen. Spread the product on a dry lawn soon after mowing.