Down To Earth™ Rock Phosphate 0-12-0 is sourced from a marine sedimentary deposit laid down millions of years ago. It is a natural, untreated source of phosphorus and calcium. It is essential for building soil phosphate levels for long-term plant productivity and for preventing calcium deficient soils. It should be applied to soils prior to planting and can be mixed with compost or manures for additional soil building benefits. This premium powder grade is an excellent nutrient resource for all types of flowering plants including bulbs, fruits, shrubs, trees and vegetables.