Relative contributions of inorganic phosphorus fractions to the labile phosphorus status of soils and uptake by rice
Kumaraswamy, K.; Sreeramulu, U.S.
Journal of the Indian Society of Soil Science 39(2): 308-315
In an investigation with soils of Koduveri, Vyalogam, Kalathur and Madukkur series, representing the major rice growth areas of Tamil Nadu, the relative contributions of the active inorganic P fractions to the P extracted by some soil test methods (chemical) and to the P uptake by the rice crop were studied. The results show that the Al-P and Fe-P contribute to the labile P pool in all the four soils, accounting for 85 to 95 per cent of the variations in the Olsen-P and Bray No. 1-P. Ca-P fraction, appeared to contribute very small portion to the P extracted by these methods. Olsen and Bray No. 1 extractants were found to be more consistent in extracting P from specific P fractions in all the soils than the other three extractants of Truog, Mehlich and Morgan. In the Koduveri and Vyalogam soil series, 82 to 89 per cent of the P uptake by the rice crop was accounted for by Fe-P and Al-P were greater contribution from Fe-P. In Kalathur and Madukkur soil series, 77 to 84 per cent of the P uptake by the crop was accounted for by Al-P.