Calphos 0-3-0 is a rich organic source of colloidal phosphate and calcium that delivers a combination of readily available and slow release nutrients in an easy to use granular form. It's a natural, untreated soft phosphate with colloidal clay containing valuable minor minerals in addition to phosphorus. Rich in trace minerals making it excellent for all crops including vegetables, fruits and flower. Calphos soft rock phosphate is comprised of prehistoric skeletal remains present in oceanic sediment and contains a minimum total of 20% P2O5 and 20% calcium. 50 lb bag Available in powder or granular form. Use 5 lb per 100 sq. ft. on phosphate deficient soils and less on fertile soil. Supplies Phosphorous and calcium up to 5 years. OMRI Listed & cdfa Organic Input Material.