Charge characteristics and exchangeable cation status of Korean Ultisols and Alfisols and Thai Ultisols and Oxisols

Shin-Ichiro Wada, K. WADA

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Abstract

The charge characteristics of A1 or Ap and B2 horizon samples of total 23 Ultisols, Alfisols and Oxisols in Korea and Thailand were studied by measuring the retention of NH4+ and NO3 at different pH values (4–8) and NH4NO3 concentrations (0.1–0.005 m). The magnitude of their negative charge (σ; meq/100g) was dependent on pH and NH4NO3 concentration (C; m) as represented by a regression equation: log σ=apH +blogC +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 NO3 was less than 1 and 2–3 meq/100 g for the A1 or Ap and B2 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 B2 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

Original languageEnglish
Pages (from-to)21-29
Number of pages9
JournalJournal of Soil Science
Volume36
Issue number1
DOIs
Publication statusPublished - Jan 1 1985

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)
  • Soil Science
  • Earth and Planetary Sciences(all)

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