Proposed revisions to the diagnostic critera for andic and vitric horizons and qualifiers of ardosols in the world reference base for soil resources

Tadashi Takahashi, Masami Nanzyo, Sadao Shoji

研究成果: Article査読

6 被引用数 (Scopus)

抄録

World Reference Base for Soil Resources (WRB) was published in 1998 and has begun to be used all over the world. We examined the definitions of andic and vitric horizons and qualifiers (lower-level units) of Andosols in the WRB by using the Tohoku University World Andosol Database (TUWAD) and proposed several revisions. Among 5 items of the definition for the andic horizon, we considered that the requirements of clay and volcanic glass contents should be deleted due to the difficulty in their accurate determination with the progression of soil weathering. In relation to this revision, correction of vitric horizon was also proposed. Although two major types of andic horizons, silandic and aluandic, are specified in the andic horizon definition, the aluandic type is not included in the qualifiers. Because aluandic volcanic ash soils have unique properties and are extensively distributed, the aluandic qualifier should be included in the lower level units of Andosols. Soil texture is used for the definition of arenic, luvic and vatic qualifiers. Therefore, these qualifiers should be modified or deleted. Both melanic and fulvic qualifiers are required to obtain the Munsell color value (moist) and chroma of 2 or less. To distinguish fulvic Andosols from melanic Andosols, the Munsell color and melanic index requirements for a fulvic horizon should be modified. Since Andosols with buried non-Andosols occur in a significantly large area, the thaptic qualifier should be used.

本文言語English
ページ(範囲)431-437
ページ数7
ジャーナルSoil Science and Plant Nutrition
50
3
DOI
出版ステータスPublished - 2004 2月 1
外部発表はい

ASJC Scopus subject areas

  • 土壌科学
  • 植物科学

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