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A New Equilibration Method for Cation‐Exchange Capacity Measurement
Author(s) -
Matsue Naoto,
Wada Koji
Publication year - 1985
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1985.03615995004900030008x
Subject(s) - chemistry , cation exchange capacity , adsorption , analytical chemistry (journal) , saturation (graph theory) , centrifuge , soil water , chromatography , soil science , mathematics , physics , combinatorics , nuclear physics , environmental science
A method is proposed for the measurement of cation‐exchange capacity (CEC) of leached soils carrying both variable and constant negative charges at conditions pertinent to the field. The method consists of equilibrating a soil with 0.01 M SrCl 2 (five centrifuge washings), replacing the retained Sr with 0.5 M HCl (one centrifuge washing) and determining the replaced Sr by atomic absorption spectrophotometry. The equilibrium pH is measured with the final 0.01 M SrCl 2 washing. If desired, exchangeable bases and Al can be determined by collecting the 0.01 M SrCl 2 washings. This method was developed because we found that the Gillman's BaCl 2 ‐MgSO 4 CEC method has problems due to specific adsorption of SO 2− 4 . For evaluation, the CEC obtained by the proposed method was compared with the sum of exchangeable bases and Al and with the CEC obtained by other methods including saturation‐equilibration with 1 M SrCl 2 ‐0.01 M SrCl 2 and 1 M NH 4 OAc‐0.05 M NH 4 OAc (pH 7.0), respectively.