St. George Black Rock Dust and BioChar Blend. For soil and ground applications targeting remineralization and phosphorus management. Use as an add mixture to soil, growing media, compost and direct to ground in planting beds. For nutrient management, use in cultivation or areas of animal confinement where excess phosphorus or nitrogen leaching are a concern. Suggested use: 10 pounds per 100 square feet in gardening applications incorporated into the soil. Use up to 5% by volume in potting soils or other planting mixes. All natural for organic production. Ships in a 40 pound box. A True Vermont Original.