Available Soil Phosphorus in Relation to Sesbania Greenmanure Incorporation in Calcareous Soils

Olsen P and inorganic phosphorus fractions in ten calcareous soils amended with Sesbania aculeata greenmanure and incubated for period ranging from 0 to 60 days were investigated in laboratory. Incubation of soil with graded levels of inorganic P without sesbania addition resulted in decreased amount of Olsen P up to 40 days of incubation and thereafter it increased. The release of P from soils amended with greenmanure was maintained at a higher level. Sesbania addition mitigated the adverse effect of CaCO₃ on P availability. The results suggest that amending of calcareous soil with greenmanure increased labile inorganic p.and Fe and saloid-P fractions. thus enhancing the availability of P in soils.