Phosphorus in rock phosphate mineral is mostly in the form of tricalcium phosphate, which is water-insoluble. Phosphorus dissolution in the soil is most favorable at a pH. The slow dissolution of phosphorus from rock phosphate dust added to the soil, allowing more phosphorus uptake by the plant roots. Organic manure can prevent ions of other elements from locking phosphorus into insoluble forms. The phosphorus in phosphate enhanced organic manure is water-insoluble, so it does not
leach into ground water or enter runoff.