Phostrell 0-6-0 with 6% available Phosphorous and 32% available Calcium is a blend of Bone Char and Calcium Carbonate to provide a better level of available Phosphate (Bone char) as well as Calcium and Micro nutrients (Calcium Carbonate). General Application Rate for most crops is 10 lb / 1000 sq ft. or 400#/ acre.  Application is recommended for maintenance of existing crops. Or use where field prep requires phosphorus level improvement.