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Charge characteristics and exchangeable cation status of Korean Ultisols and Alfisols and Thai Ultisols and Oxisols
Author(s) -
WADA S.I.,
WADA K.
Publication year - 1985
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1985.tb00310.x
Subject(s) - ultisol , oxisol , chemistry , zoology , mathematics , soil water , soil science , environmental science , biology
SUMMARY The charge characteristics of A 1 or Ap and B 2 horizon samples of total 23 Ultisols, Alfisols and Oxisols in Korea and Thailand were studied by measuring the retention of NH 4 + and NO 3 − at different pH values (4–8) and NH 4 NO 3 concentrations (0.1–0.005 m ). The magnitude of their negative charge (σ − ; meq/100g) was dependent on pH and NH 4 NO 3 concentration (C; m ) as represented by a regression equation: log σ − = a pH + blog C + c . The values of the coefficient a (0.04–0.226), b (0.03–0.264) and c (–0.676–1.262) were correlated with the kinds of the soil and horizon and with the region where the soil exists. The retention of NO 3 − was less than 1 and 2–3 meq/100 g for the A 1 or Ap and B 2 horizon samples, respectively. The sum of exchangeable base and Al (‘effective’ CEC) was close to and higher than the magnitude of permanent charge (=σ − measured at pH = 4.3 and at C = 0.005 m ) for one‐third and two‐thirds of samples, respectively. A σ − value of 16 meq/100 g clay at pH = 7 and C = 0.01 m was found appropriate to separate the B 2 horizons of Thai Ultisols and Oxisols from those of Korean Ultisols and Alfisols. Korean Alfisols and Ultisols and Thai Ultisols were distinguished from each other on the status of exchangeable base and Al