Argillic, Kandic, and Natric Horizons - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 97

Table 11.4 (continued)
Area Soil taxa Role of soil-forming factor Citations

WV Typic Hapludults Argillic-like horizon on Cotiga

Mound in 2100 yr

Cremeens ( 1995 )

CA, NV, AZ Haplargids,

Paleargids

Argillic occurs only in soils
>

Nettleton
et al. ( 1975 ) 12000 yr old

ID [Not provided] Argillic occurs only in soils

>

Othberg
et al. ( 1997 ) 14500 yr old

UT Haplargids Argillic occurs in soils 9000 yr old Southard and

Southard
( 1985 )

NV Natrargids Natric occurs in soils < 6600 yr old Alexander and

Nettleton
( 1977 )

suggested that the clay-enriched horizon in many aridic environments was below
the current wetting zone; it may have been inherited from a moister environment
during pluvial periods (Gile and Grossman 1968 ; Eghbal and Southard 1993 ;
Khormali et al. 2003 ; Khademi and Mermut 2003 ). Moreover, studies examining
argillic horizon formation across regional environmental gradients show that clay
illuviation is stronger in the humid portion than in the dry portion of the landscape
(Rabenhorst and Wilding 1986a , b ; Gunal and Ransom 2006 ; Khormali et al. 2012 ).
Along an elevational gradient in Nevada, argillic horizons formed more readily in
udic and aridic-udic soil-moisture regimes than in an aridic soil-moisture regime
(Elliott and Drohan 2009 ).
Parent material is a critical factor influencing clay illuviation (Table 11.4 ).
Argillic horizons tend to form more readily where water is arrested at the contact
between two lithological units (Cabrera-Martinez et al. 1989 ; Ogg and Baker 1999 ;
Bockheim 2003 ; Shaw et al. 2004 ), in stratified materials (Hopkins and Franzen
2003 ), or where a lithic or paralithic layer is present (Bruckert and Bekkary 1992 ;
Aide et al. 2006 ; Blanco and Stoops 2007 ). Soils with abundant coarse fragments
often contain deeper argillic horizons, especially in Ustolls, Ustalfs, and Argids
(Gile and Grossman 1968 ; Rabenhorst and Wilding 1986a , b ), possibly because
water containing suspended silicate clays is able to move downward more readily
in the profile. Bruckert and Bekkary ( 1992 ) described this as the “rock effect.”
There may be a direct correlation between the clay content of the argillic horizon
and the clay content of the soil parent material (Gile and Grossman 1968 ; Smith
and Wilding 1972 ; Franzmeier et al. 1985 ). Although loess rejuvenation favors
the development of argillic horizons (Mubiru and Karathanasis 1994 ), calcareous
dust (Gile and Grossman 1968 ; Elliott and Drohan 2009 ) and calcareous parent
materials (Smeck et al. 1968 ) may inhibit clay illuviation. High exchangeable
Na percentages may favor clay illuviation by dispersing clays and enabling the
formation of natric horizons (Alexander and Nettleton 1977 ). Several of the larger
areas not containing an argillic horizon in Fig. 11.2 occur in areas with thin drift
over granitic bedrock, including New England, the upper Great Lakes region,
and the Sierra Nevada Range.