Geoscience Reference
In-Depth Information
Table 4.3 Contd...
Histic
Organic material in
Hortic
Black soil of manured orchard
poorly aerated
environment
Hydragric
Cultivated horizon, sub-
Irragric
Enriched with fine particles
merged in water
by continued irrigation
Melanic
Black (in Andosols)
Mollic
Brown, well-structured, base
saturation > 50%
Natric
With exchangeable
Nitic
With iron and clay,
sodium
and shiny ped faces, but
without illuviation
Petrocalcic
Indurated by CaCO
3
Petroduric
Indurated by silica
Petrogypsic Indurated by CaSO
4
Petroplinthic Indurated by iron
Pisoplinthic
With iron nodules,
Plaggic
Linked to the plaggen
cemented
technology
Plinthic
With accumulation of
Salic
With accumulation of salt
iron, quartz, kaolinite
Sombric
Illuvial humus, dark,
Spodic
With accumulation of organic
not associated with Al;
matter, Al and sometimes Fe
tropical mountains
Takyric
Massive, silty clay surface
Terric
Enriched through refuse or
crust in arid environment
composts
Thionic
Rich in sulphates and
Umbric
Surface horizon rich in organic
sulphides
matter, dark, base saturation
> 50%, pH < 5.5
Vertic
With slickensides
Voronic
Thick Mollic horizon, black,
biologically very active, well
structured, base-rich
Yermic
Desert pavement
Diagnostic properties (Table 4.4) are much fewer than the diagnostic
characteristics of Soil Taxonomy.
Diagnostic properties
Table 4.4
Diagnostic properties of the WRB.
Property
Simplified definition
Abrupt textural change
Very sharp change in texture between two superposed
horizons
Albeluvic tonguing
Penetration of iron-depleted tongues in an 'Argic' horizon
Andic properties
Org. mat. > 5%, low bulk density, [Al
o
+ ½ Fe
o
]> 2% (*)
Aridic properties
Poor in O.M., very high base saturation, aeolian action
Continuous rock
Hard rock, excluding indurated horizons
Ferralic properties
Ferralic horizon but coarse-textured and CEC >24 (**)
Table 4.4 Contd...
