Phosphorus (P) is an essential element for life. In fact it is present in adenosine triphosphate (ATP) which transport in
cells the energy required for biological reactions. Deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and phospholipids
are also vital P containing molecules in animal and plant cells. After nitrogen, P is the second major element effecting plant
growth and yield. And the concentration of P in soil solution is very low, varying from 0.001mg L-1 in very poor soils to 1
mg L-1 in heavily fertilized soils. Orthophosphate anions (mainly H2PO4
- and HPO4
2-) are the form of P taken up by plants
from soil solution; however their concentration is very low because they are chemically very active and they react rapidly
with cations like calcium in alkaline soils or aluminum and iron in acid soils to form sparingly soluble precipitates, not
available to plants. The reactions resulting in the precipitation of soluble P from soil solution are generally referred to as Pfixation
or P-retention. It is estimated that because of P-fixation in soil, plants will take up the year of application, only 10 to
15% of the soluble P added as fertilizers or manure [1]. Therefore long term use of P fertilizers and organic amendments,
particularly in high P-fixation soils, will cause the accumulation of substantial quantity of P. In general half of total soil P [2]
is formed by organic P of which 10 to 50% is formed by inositol phosphates [1].