Depth Distribution of Different Forms of Phosphorus in Lateritic Soils of Coastal Region

Forms of phosphorus and their distribution in eight profiles of lateritic soils were studied. Inorganic and organic phosphorus contributed 52.2 to 99.4 and 0.6 to 47.8 per cent of total P (250 to 800 ppm), respectively. Reductant soluble plus occluded P (less active) and residual P (inactive) were predominant P forms which correspondingly constituted 29.7 and 34.0 per cent, respectively. Total, organic and reductant soluble phosphorus decreased in the solum with few exceptions. The extractable P status was very low which decreased with depth and showed close relation with Al-P. Reductant soluble, occluded, residual, organic and total phosphorus had positive and significant relation with organic carbon, CaCO₃, Fe₂O₃, Al₂O₃ and silt.