A comparative study of two methods for determination of pH, exchangeable base cations, and aluminum

The ability to compare soil chemical data achieved by different chemical extraction methods is a necessity for an efficient long-term monitoring of soils and for comparisons of results from regional soil surveys with differing standard methods. This study compares two common, methods for analysis of soil chemical properties, the combination of soil extraction in 1.0 M NH4Cl and 1.0 M KCl and the single extraction method using 0.1 M BaCl2. Results show that the two methods do not differ in extraction capability with regard to pH and exchangeable calcium (Ca) and magnesium (Mg). However, there is less agreement in extraction capability with regard. to potassium (K), sodium (Na), and aluminum (Al). For these elements, BaCl2 is less efficient than NH4Cl and KCl. Despite the differences in extraction capability between BaCl2 and KCl/NH4Cl, regression analyses showed that the methods are well correlated (high regression coefficients for all, elements). Thus, transformation of data achieved by one method to estimated values of the other method are possible. Results from this study may be an important tool for comparisons of mineral soil data achieved by the two methods.