Influence of Reaction Time on Phosphate Adsorption

The influence of reaction time on P adsorption was studied using four representative soils of Tamil Nadu viz., red, black, laterite and alluvial soils. The equilibrating solution employed was 0.01 M CaCl₂+KH₂PO₄ at 28°C±1. The results showed that P adsorption was characterised by an initial fast reaction followed by a slow process in all the soils. The rate of P adsorption was high in Ootacamund high level laterite soil, while it was slow in Tirurkuppam alluvial soil. Reasonably stable level of P in equilibrium solution was attained after 6 days in all the soils, excepting that of Kovilpatti black soil and alluvial soils which required a minimum of 8 days.