Natural rock phosphates are from deposits of apatite rock formed eons ago by sea life that left behind fossils and shells composed of calcium phosphates. This means phosphate rock is an excellent natural source of phosphorus, calcium and essential trace elements. It contains over 30% total phosphate (3-8% available) and 48% calcium. Rock phosphate is primarily used to build up phosphate where levels are low and to increase rooting activity in transplants and sprouting seeds. Rock phosphate can be applied to help plants adjust to the stress associated with transplanting. It does not burn roots, so it can be applied directly to bare root stock. Phosphates trigger root branching which gives the plant greater access to more of the nutrients it needs.
Thoroughly mix into the soil at a rate of 2 pounds per 100 square feet before seeding or planting. To feed established plants, side dress ½ cup in during the growing season. The rate can be as high as 5 pounds per 100 square feet to amend a phosphate deficiency, based on the results of a soil test. (1 ½ cups is approx. 1 lb.)
Guaranteed Minimum Analysis
AVAILABLE PHOSPHATE (P2 O5)……………………………… 3.0%
Derived From: Phosphate rock.