Phosphate esters are sub-classified according to the number of ester groups linked to each phosphate. Thus, phosphate monoesters have one carbon moiety per phosphorus, while phosphate diesters have two. Phosphate monoesters are the dominant group of organic phosphorus compounds in most soils [1]. They occur mainly as inositol phosphates, a family of phosphoric esters of hexahydroxy cyclohexane (inositol) [13] and [14]. There may be one to six phosphate groups linked to the parent inositol. Of the phosphorylated inositols, the myo isomer is most common, although other stereoisomeric forms (scyllo, d-chiro, neo) also occur in soil [14]. Other phosphate monoesters present in small amounts in soil include sugar phosphates, phosphoproteins and mononucleotides.