Rock Phosphates

ROCK PHOSPHATES - are natural deposits of phosphate in combination with calcium. The material as dug from the earth is very hard and yields its phosphorus very slowly. When finely ground and with impurities removed, the powdery material is only slightly soluble in water, but may be beneficial to plants in subsequent seasons following application. The reaction of phosphate rock with acids from decaying organic matter in the garden or compost tend to make the phosphorus available to garden plants.

Usually refined as phosphoric acid which, when combined with an alkali (sodium, potassium, ammonium and calcium) produce the phosphatic salts used as fertilizers.