Zinc adsorption in soils in relation to soil properties

An experiment was conducted during 1992 to study adsorption of zinc in 12 soils, 6 each from alluvial and lateritic zones of West Bengal, in relation to soil properties. Adsorption was higher in alluvial (Aquept) (1.23 mg/g) than in lateritic soils (Ustalf) (0.67 mg/g) and the data were fitted well to Langmuir adsorption isotherm equation. The adsorption maxima and bonding-energy values computed from the equation were also higher for the former (1.61 mg/g soil and 0.25/ppm Zn respectively) than for the latter (0.97 mg/g soil and 0.031ppm Zn respectively) groups of soils. The higher values were due to higher oontents of olay, organic carbon, CaCO 3 , and amorphous Fe-oxides and higher cation- exchange capacity and pH of the alluvial soils. Significant positive correlations of adsorption maxima and bonding energy of Zn with clay (0.84** and 0.57**) cation-exchange capicity (0.78** and 0.77**), organic carbon (0.85** and 0.62**) and amorphous  Fe-oxides (0.83** and 0.78** ) contents of the soils support these observations. Other parameters related to adsorption, viz free energy, Zn-hydroxy potential, differential buffering capacity, and supply parameters, were also found Significantly related with the soil properties.