TEXT BOX 1 – Terminology Name Abbreviation Conversion Factors Phosphorus, which has an atomic weight of 30.97, is one of the essential nutrients for living organisms. Elemental phosphorus does not occur in nature, and P is present in different inorganic (phosphate) and organic forms. Phosphorus present in different commodities is therefore often referred to as phosphate (expressed as the amount of PO5). Phosphate refers to a salt of phosphoric acid (H3PO4), such as calcium phosphate. More generally, the term phosphate is used for any oxidic form of phosphorus. Rock phosphate is a natural rock containing one or more calcium phosphate minerals. It can be used immediately after grinding or after chemical processing in the manufacture of commercial phosphate fertilisers (FAO, 2009). Rock phosphate is mostly used to quantify mine production, reserves and reserve bases of phosphate (chapter 2) Rock phosphate is a natural rock containing one or more calcium phosphate minerals. It can be used immediately after grinding or after chemical processing in the manufacture of commercial phosphate fertilisers (FAO, 2009). Rock phosphate is mostly used to quantify mine production, reserves and reserve bases of phosphate (chapter 2) The amount of phosphate present in different forms is often expressed as phosphoric oxide. As such, PO5 is the common denominator when comparing different phosphoruscontaining fertilisers, for instance in terms of total production, consumption and trade (Smil, 2000). Bone phosphate of lime is the trade name for tricalcium phosphate [Ca 3(PO4)2] which is the primary criterion used to differentiate phosphate rocks (IFDC et al., 1998). The name is reminiscent of the time when bones were the principal source of phosphate in the fertiliser industry. At present BPL is not commonly used to classify the quality of phosphate rock and is not used in this report. 9 Elemental phosphorus P P = 0.4364PO5 P = 0.1997BPL Phosphate - See PO5 Rock phosphate RP RP = 0.25 - 0.4 PO5 (Phosphate) Phosphorus pentoxide or phosphoric oxide PO5 PO5 = 2.2914P PO5 = 0.4576BPL Bone phosphate of lime BPL BPL = 2.1852PO5 Pagina 18

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