Jonathan Green 11357 MAG-I-CAL Plus for Lawns in Alkaline + Hard Soil,15000 SqFtMAG I CAL PLUS for Lawns in Alkaline + Hard Soil is a unique, multi faceted, soil enhancing food that lowers soil pH, loosens hard soil, and stimulates soil microbes. MAG I CAL PLUS for Lawns in Alkaline + Hard Soil contains fast acting sulfur which lowers soil pH to enhance nutrient availability from lawn foods. It also fortified with a patented, quick releasing gypsum to help break up clay and compacted soil for better air, water, and root