Characterisation of Added and Soil Phosphorus in Some Soils of Haryana

The P sorption characteristics of some soils of Haryana were studied in laboratory. Four surface soils were equilibrated with varying amounts of P for a period of seven days. At low concentration of P in the equilibrium solution, the adsorption could be described by Langmuir isotherm equation. With Tempkins equation, the plots were found to be curvilinear. The soils removed 58 to 68.7% of added P from solution. However, the soils varied considerably as to the sorted P exchangeability. The calcareous soils, with high pH (8.6 to 8.7) had low exchangeability. Sorption capacity appears to be related to surface area, clay, Fe₂O₃ contents positively. The CaCO₃ content decreased the exchangeability of sorbed P and helped in removing P front solutions.