ABSTRACT

Cation exchange capacity (CEC) is a reversible chemical reaction. The cations held on the surface of the soil minerals and within the crystal framework of some mineral species and those which are a part of certain organic compounds can be reversibly replaced by those of salt solutions and acids. CEC is expressed in milliequivalents (meq) per 100 g of soil. It is defined as the sum of the exchangeable cations of a soil. The advantages of the ammonium acetate CEC method are that it is easy to use, it is highly buffered so the soil remains neutral throughout the leaching process, and the ammonium ion is easy to determine analytically. Some exchangeable ions are more easily replaced than others due to the salt solution and the characteristics of the soil.