Desert soils, paleosols and duricrusts - Climatic Change in Deserts - page 261

Table 15.1. Major international soil groups recognised in drylands. (Modified from
IUSS Working Group WRB, 2007 .)

Soil Group Characteristics

Andosols Soils formed in volcanic ash, with abundant volcanic glass (Andisols)
Arenosols Sandy soils with minimal texture contrast and weak or no soil horizons
(Entisols)
Cambisols Soils with weakly developed horizons, depleted of bases and/or iron and
aluminium but with some weatherable minerals; occur mainly in humid
and subhumid areas (Inceptisols)
Chernozems Soils formed under grassland in semi-arid to subhumid areas; rich in humus,
bases and calcium carbonate (Mollisols)
Ferralsols Soils rich in iron or aluminium (Ultisols)
Fluvisols Young soils in alluvial deposits still showing signs of alluvial stratification
(Entisols)
Gleysols Soils that have been permanently or sporadically waterlogged; grey or green
colours; ironstone nodules may occur in the subsoil
Gypsisols Soils of arid areas with secondary accumulations of gypsum (calcium
sulfate)
Histosols Highly organic soil with at least 20-30 per cent organic matter by weight in
a layer at least 40 cm thick (Histosols)
Kastanozems Red-brown, humus-rich soils of semi-arid steppes and grasslands (Mollisols)
Lithosols Shallow soils, mainly composed of unweathered rock fragments

Luvisols Texture-contrast soils with higher clay content in the subsoil; the eluvial

(Ae) horizon overlies an illuvial (Bt) horizon enriched in clay

Planosols Soils with a bleached, light-coloured, near-surface horizon over a horizon

with a higher clay content (Ultisols)

Podzols Ashy grey acidic soils formed on sands; strongly leached surface layer;

subsurface accumulation of humus mixed with amorphous iron and/or
aluminium (Spodosols)

Rankers Soils developed over non-calcareous rock, with A/C profiles (Entisols)

Regosols Soils formed on deep, unconsolidated, recently deposited sands or alluvium

(Entisols)

Rendzinas Red clay-rich soils formed on limestone or eolianite, with high calcium

carbonate content

Solonchaks Saline and often alkaline soils of hot arid areas; often formed on playas or

sebkhas with salt forming near the surface as a result of strong evaporation

Solonetz Soils with tough, impermeable hardpan and domed prismatic structure;

often saline and alkaline.

Vertisols Heavy, dark churning clay soils with deep vertical cracking in the dry

season; contain abundant swelling clay minerals (notably,
montmorillonite); Variable salinity and alkalinity (Vertisols)

carbonate nodules, gypsum crystals or salt content. The use of the letters A, B and
C for soil horizons is now universal but was originally applied in Russia specifically
to chernozems ( Table 15.1 )( Soil Survey Manual , 1951, p. 176). Soil horizons are
defined in Section 15.4 .