Permagreen PRO Mushroom Compost is a 100% organic soil amendment. The other brands out there are using the spent compost that mushrooms have been grown in. They contain salt residues from the chemicals fed the mushrooms. Permagreen PRO Mushroom Compost is a blend of composts, wheat straw, Sphagnum Peat, and pearlite. It's a tried and proven formula used by the mushroom growers. This is s great soil amendment. It helps loosen our clay / alkaline soils and helps loosen our heavy clay soils and supplies the natural trace elements and nutrients the plant needs. Use it where you want to improve growing conditions.