A Comparison of Ammonium Acetate, Barium Acetate, and Buffered Barium Chloride Methods of Determining Cation Exchange Capacity

Pratt, P. F.; Holowaychuk, N.

A Comparison of Ammonium Acetate, Barium Acetate, and Buffered Barium Chloride Methods of Determining Cation Exchange Capacity

1954

Pratt, P. F. | Holowaychuk, N.

The cation exchange capacities of several profile samples of soils were determined using three different methods. Total exchangeable cations were determined and used as a criterion for evaluating the different methods of determining the exchange capacity. For all soil samples the NH₄OAc method underestimated the exchange capacity and so produced distorted exchange capacity profiles. The Ba(OAc)₂ method gave exchange capacity values which were equal to the sum of exchangeable cations, except with highly acid soils where it gave low values. The BaCl₂-buffer exchange capacity gave values that were nearly equal to the sum of the exchangeable cations for all samples tested. The Ba(OAc)₂ or BaCl₂-buffer methods, in which Ba is replaced by 0.05 N HCl and the Ba determined using an acetylene flame with a model 52 C Perkin-Elmer photometer, cannot be used for some samples because of Ca interference. Some slightly acid soils gave sufficient Ca release during the HCl extraction to interfere in the Ba determination. This interference was removed by washing the soil with HCl before leaching with the BaCl₂-buffer and by replacing the barium with NH₄OAc.

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