"BONE MEAL [bone meal] finely ground bone used as a fertilizer for its
content of phosphate and nitrogen (about 23%-30% available phosphate
and 2%-4% nitrogen); it is an expensive form of phosphoric acid when
compared with superphosphates . Bone meal is also fed to farm animals
to supply needed mineral food constituents, e.g., calcium and
phosphorus. " From the Columbia Encyclopedia. Bone meal is expensive,
but works fine for organic gardeners. Should I need phosphate I use
superphosphate or a fertilizer with a high middle number. BUT only
after a soil test to determine that I need it.