Comparison of Two Different CEC Determination Methods Regarding the Soil Properties

Cation Exchange Capacity (CEC) is a parameter which reveals extent of the soil surface sites that can potentially retain cations by electrostatic forces. Different soil types vary in CEC values, which in turn depend on many factors (soil pH, texture, organic matter content, etc.). CEC is a good indicator of soil quality and fertility. CEC can be measured using different methods and it is difficult to recommend a universal one. The most commonly used methods include exchange of cations with a specific solution of known salt concentrations that are not present in the soil, followed by analytical detection of these cations by standard techniques. The aim of this study was to determine and compare the CEC and the amount of exchangeable cations measured on the same samples (n = 50) of soil with different characteristics, using two common methods (one with BaCl2 and the other with CH3COONH4 solution), and to determine their dependence on soil pH, content of organic matter and clay content. Correlation between the values of CEC measured with two different methods was very high (r=0.83). Still, significant difference between the two methods (F test, p ≤ 0.05) was noted. Transformation of the CEC values achieved by one method into the estimated values of the other method is possible. Very high correlation was observed between CEC (CECBaCl2 and CECCH3COONH4) and OM content in soil (r=0.78 and r=0.80), high correlation with soil pH (r=0.58 and r=0.52), and very weak or no correlation with clay content (r=0.12 and r=-0.04). Also, soil salt content influenced measured values of CEC (in CH3COONH4) and sum of exchangeable cations (in BaCl2)