Loosens heavy clay soils. Works like millions of tiny hoes. Lets air and water penetrate. Adds vital secondary nutrients like calcium and sulfur. Counteracts winter salts damage. Gentle-acting, noncaustic, nonburning, nontoxic. Improves structure of compacted clay soils thus increasing porosity. Virtually dust free and easy to spread. Recommended rate: 1 bag to 1,000 to 2,000 sq. ft.