Original Articles: 2013 Vol: 5 Issue: 6
Studies on adsorption mechanism and kinetics of magnesium in selected cocoa growing soils in Nigeria
Several soil evaluations have found magnesium deficient in most cocoa plantations in Nigeria. Authors have recommended the use of magnesium fertilizers to address the deficiency. For appropriate fertilizer application and effective utilization of applied fertilizer, understanding the adsorption kinetics and magnesium holding capacity of each soil will help in making precise recommendation in order to prevent wasting of resources and contamination of the environment with un-adsorbed magnesium. Soil samples were collected with soil auger at a depth of 0-30cm from selected cocoa plantations in Lodu, Itu, Ikom, Asaba and Uhonmora in Abia, Akwa Ibom, Cross River, Delta and Edo States respectively. One gram (1.0 g) of each sample was equilibrated with 30ml of 20, 40, 60, 80 and 100 mg Mg L-1 solution. Another portion (1.0 g) of each sample was equilibrated with 30ml of 70 mg Mg L-1 for 40, 80, 120 and 140 minutes to study the kinetics of Mg2+ ions in soil. The data generated were fitted into various adsorption Isotherms and kinetic models. Results showed that, Freundlich model best described the adsorption of magnesium indicating Mg adsorption on heterogeneous surfaces. Mass transfer kinetic model best described the kinetics of Mg2+ adsorption. Sample obtained from Cross River State had the highest adsorption capacity for magnesium compared with the rest of the soils. Clay and organic carbon were the main soil properties that influenced Mg2+ adsorption in the soils.