Abstract

                                Thirty eight soils collected from nine profiles representing the four major soil groups viz., red, black, laterite (high level and low level) and alluvial soils were examined for different forms of inorganic P and their distribution with depth. There was a marked varia- tion in the vertical distribution of P fractions viz., Al-P. Fe-P. Ca-P. Red. sol. P and Occlu- ded P. Total P and inorganic P decreased with depth in most of the profiles except in red and black calcareous and Aduthurai alluvial soils. No definite pattern of distribution of Al-P and Fe-P was observed but the surface layers were rich in Al-P and Fe-P. Ca-P increased with depth in calcareous soils and Aduthurai alluvial soil. Red. sol. P and Occluded P increas- ed with depth in most of the soil profiles. Among the inorganic P fractions. Al-P and Ca-P dominated in black and alluvial soils, whereas Fe-P, Red, sol. P and Occluded P were high in laterite soils.

Key words :