Vegetos

Abstract

Zinc adsorption was studied in sixteen soils varying in crop residue levels. Adsorption process was executed by equilibrating 2.0 g soil in 40 ml 0.01 M CaCl₂ solution containing 5, 7.5, 10, 15, 25, 50, 75, 100 and 200 mg Znl⁻¹. Sorption data were fitted to Freundlich and Langmuir adsorption models. The data were best fitted in both Freundlich and Langmuir equations as evidenced by higher correlation coefficient values ranging from 0.87 to 0.99. The adsorption maxima of Zn ranged from 212 to 435 mg kg⁻¹ and bonding energy from 0.0083 to 0.0434 and 0.0089 to 0.268 mgl⁻¹ at 15°C and 30°C, respectively. The adsorption parameters, 1/n and K, ranged from 1.1172 to 2.3208 and 3.0562 to 10. 1838 at 15°C and 1.1172 to 2.3490 and 3.0562 to 10.4750 at 30°C, respectively. Adsorption of Zn increased with the increasing levels of Zn and crop residues. The maximum adsorption of Zn was observed in the treatment, CR₁₀₀Zn₀, whereas the minimum in the treatment, CR₀Zn₀.