Didier Blavet

Effect of the soils properties on the sorption capacity of phosphorus and ammonium by alkaline soils of the semi-arid areas

Soils samples were collected at different depths (from 0 to 120 cm) from tree sites of Tunisia (Chott Mariem, Enfidha and Kondar). The minerals and physicochemical properties were analyzed. Then the capacity sorption of phosphorus and ammonium was carried only in the samples collected from the surface depth (0-25cm) using the batch processes. The results showed that most soil samples have a clayey texture. The available of nutriment and heavy metals was different and varied with the sites and depths. The sorption of phosphorus and ammonium was rapid initially and gradually diminished to attain equilibrium. The equilibrium was reached after 72 h for phosphorus sorption and 300mn for ammonium sorption. Also the levels of P adsorbed were; 6.27, 6.84 and 6.92 mg P g−1 and ammonium adsorbed were 5.83, 6.5 and 6.3 mg NH4 + g −1 respectively from the soil Chott Mariem, Enfidha and kondar. Applications of the following kinetics models: pseudo-first-order, pseudo- second-order and Elovich model to the data show that the rates of phosphorus and ammonium sorption were best predicted by the pseudo-second-order kinetic model as seen from the correlation coefficient R2 (≥0.98).