INFLUENCE OF pH

This study determined and compared the values of exchangeable cations Mg2+,Ca2+,Na+,K+,and cation exchange capacity(CEC) of clay soil samples in Nigeria, using different pH media (4,5,7,8).Two different clay soil were analysed. Ammonium acetate displacement method was used for the analysis. The chemical analysis were performed using Atomic Absorption Spectrophotometry(AAS),to determine the Mg2+,Ca2+content;Flame photometer to determine Na+,K+,content andColorimeter; used to determine ammonium nitrogen content.The result showed that Sample 1,Exchangeable cations (E.C) for Mg 2+had its highest at pH 7(0.198±0.03) and its lowest value at pH 4(0.142±0.04), Ca2+ had its highest at pH 7(2.692±0.08) and its lowest value at pH 5(1.188±0.16), Na+had its highest value at pH 8 (1.884±0.05) and its lowest value at pH 5(0.409±0.03), andK+ had its highest value at pH7(0.926±0.09) and its lowest value at pH 8 (0.415±0.03)The result showed that Sample 2, Exchangeablecations (E.C) for Mg2+, had its highest at pH 5(0.047±0.002) and its lowest value at pH 8(0.032±0.003), Ca2+had its highest at pH 8(1.339±0.08)and its lowest value at pH4(0.349±0.06),Na+had its highest value at pH8(2.185±0.04) and its lowest value at pH 4(1.598±0.08), and K+ had its highest value at pH 8(0.693±0.06) and its lowest value at pH 5(0.415±0.07). Generally there was a decrease in CEC as the pH increased in the acidic media from pH 4 to 5 and an increase in the CEC as the pH approached neutral, and also a decrease when the pH was increased to 8(basic medium).From the results obtained,it is evident that pH is animportant soil property,because when the clay sample was treated at different pH,the values of the cations as well as their exchangecapacity was greatly was affected i.e they had different pH values when subjected to different medium