Argillic, Kandic, and Natric Horizons - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 88

Table 11.1 Soil textural horizons and their approximate history and current definition in Soil
Taxonomy (Bockheim and Hartemink 2013 )

Current definition in soil taxonomy
(abridged) Horizon History

Bt Part of the B2 horizon (“zone of

accumulation” or “zone of
compaction”) until 1951. The term was
included in the 1951 edition of the Soil
Survey Manual . However, it does not
appear to have been used widely in
Europe (Kubi¨na 1950 ); in the USA
Baur and Lyford ( 1957 ) used “t” to
designate clay accumulation in some
New England soils. Once the 7th
Approximation (Soil Survey Staff 1960 )
was published, the term experienced
widespread use

An accumulation of silicate clay that has
formed within a horizon and/or has
subsequently been translocated within
the horizon or has been moved into
the horizon by illuviation, or both.
Evidence of clay accumulation by
coatings on ped, lamellae, or as bridges
between mineral grains

Argillic Included in the 7th Approximation in 1960

(Soil Survey Staff 1960 ). However, it
does not appear to have been used in
ASA-SSSA-CSSA publications until
1964, when Harpstead and Rust ( 1964 )
used the term for some Alfisols in
Minnesota, USA. The “Supplement to
Soil Classification” was added in 1967,
and the term became widely used
shortly thereafter

A subsurface horizon with a significantly
higher percentage of phyllosilicate clay
than the overlying soil material.
It shows evidence of clay illuviation

Natric Included in the 7th Approximation in 1960

(Soil Survey Staff 1960 ). However, it
does not appear to have been used in
ASA-SSSA-CSSA publications until
1974, when Sharma et al. ( 1974 ) used
the term for a Natraqualf in Illinois
(USA)

An illuvial horizon that is normally present
in the subsurface and has a significantly
higher percentage of silicate clay than
the overlying horizons. Evidence
of clay illuviation that has been
accelerated by the dispersive properties
of sodium

Kandic Introduced in Soil Taxonomy between

1985 and 1987 and first appeared in the
3rd edition of Keys to Soil Taxonomy

Subsurface horizon that is dominated by
low-activity clays and underlying a
coarse-textured surface horizon

were integrated in the classification of horizons and in the classification of the
whole soil profile. The Bt horizon (t for ton , German for clay) is now integrated in
most soil and horizon classification systems. The French developed the concept of
the argillic horizon and the formation of coatings (Duchaufour 1998 ). Main char-
acteristics of a B horizon are coatings formed of fine colloidal particles deposited,
and these have been termed cutans. Cutans can be amorphous organomineral
complexes termed organans or sesquioxide complexes termed sesquans, or cutans
are formed of crystalline clay minerals laid down in parallel orientation and then
they are called argillans. Such argillans characterize the Bt horizon of argillic soils
(Duchaufour 1998 ). An overview of the different horizons in Soil Taxonomy ( 2010 )
and their approximate conceptual history is given in Table 11.1 .