Dissolution and transformation of three major indigenous rock phosphates (Udaipur rock phosphate, Mussoorie rock phosphate and Purulia rock phosphate) at different P levels and soil water regimes in an acid Alfisol were studied in the laboratory. The dissolution of rock phosphate as assessed by different extractants followed the order, Olsen's P > Bray P1 > CSP > WSP. Rock phosphates by and large had similar effects. However, water soluble source (superphosphate) had an edge in dissolution over rock phosphate sources. The transformation of applied P through superphosphate androck phosphate to inorganic P fractions in the incubated soil, followed the order: Fe-P > Al-P > Ca-P. Superphosphate treatment recorded higher values of inorganic P fractions and rock phosphate sources were at par. The results indicate the dominance of Fe-P fraction in acid soils developed under high rainfall conditions and also show that Olsen's P, Bray P1. CSP and WSP were significantly and positively correlated with inorganic P fractions in the soil.
Rock phosphate, acid Alfisolavailable P, inorganic P fractions, dissolution
