Jonathan Green's Mag-I-Cal® for lawns in acidic 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 functions. Lawns thrive in soil with pH levels between 6.2 and 7. When the pH level of the soil is below this range grass becomes light green, weeds persist and fertilizer nutrients are not fully absorbed. Mag-I-Cal® Plus also contains humates to stimulate soil microbial life. When soil chemistry and biology are balanced, nutrients from lawn foods are not wasted and the grass will thrive.