An Investigation into the Effect of Calcium and Sodium Ions on pH Dependent Retention of Phosphate by Some Soil Samples and Correlating It to the Soil Properties: a Study Done at Visakhapatnam City

Abstract

In the present study the adsorption of phosphate was investigated in presence of alkali and alkaline earth metals by the soil samples collected from a heterogeneous industrial zone. The study was carried out at varying pH medium   at two different concentrations    of phosphate ions. Sample no.5 (Table No. 2 and 3) which was collected near a petrochemical industry showed the highest amount of adsorption. It is assumed that the ionized phosphate species undergoes complexation with metal ions present in the sample.CEC and organic carbon was found to be highest for Sample no. 5. Sample no.3 (Table No. 2 and 3) which was collected in the vicinity of a fertilizer industry has shown to have lower adsorption of phosphorus as compared to other samples. The correlation coefficient between organic matter and P adsorption was found to be fairly good (r = 0.94) in calcium chloride medium. The equation was found to be y =18.16x. CEC of the soil samples could be satisfactorily related to phosphorus adsorption. The variation of adsorption of phosphates with CEC of soil samples at pH 5 at higher concentration of phosphate has been shown in the Figure No. the equation was found to be y=2.546x and R² = 0.80. The maximum adsorption of phosphate was observed at pH 5. Adsorption of phosphate was found to be fairly correlated with pH in calcium chloride medium. The equation was found to be y = 0.745x²-11.40x +113.7 with R² = 0.750.