Forms of soil P and their characterisation

FORMS OF SOIL P AND THEIR CHARACTERISATION 4.1. Chemical characterisation of soil P 

Soil P occurs in a wide variety of different inorganic and organic forms. About 200 phosphate-containing minerals are knownand in soils the orthophosphate anion also occurs in combination with aluminium and iron oxides and hydroxides, clay minerals, solid carbonates and soil organic matter. Small amounts of condensed P of mainly microbial origin, are also found in soil as pyrophosphate and higher polyphosphates.  

In the surface horizons of most soils, P also occurs in organic forms in amounts that can vary widely from about 20 to 

Soil P mainly occurs as mono- and diesters (i.e. (RO).PO3H2 and (RO)(R O).PO H) and their chemical diversity is due mainly to the organic moieties R and R. Several excellent reviews have appeared on the composition of soil 1 15,66,87,111 pre- 

Instead of isolating inositol phosphates from alkali extracts, ester P including inositol phosphates has been precipitated from soil with Ti to give recoveries comparable with more commonly used procedures.  

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