Agriculture Reference
In-Depth Information
Table 19.3
Descriptive Summary of Sample Diagnostic Materials
Examples of Unique Qualifier Definitions
Anthropogenic
soil material
Unconsolidated mineral or organic material produced largely by human activities and not
significantly altered by pedogenetic processes
Organic soil
material
Organic debris, which accumulates at the surface and in which the mineral component
does not significantly influence soil properties
Sulfidic soil
material
Waterlogged deposit containing sulphur, mostly sulphides, and not more than moderate
amounts of calcium carbonate
Tephric soil
material
Unconsolidated, non- or only slightly weathered products of volcanic eruptions, with or
without admixtures of material from other sources
Table 19.4
Sample of WRB Qualifiers and Their Definitions
Examples of Unique Qualifier Definitions
Carbi-
Having a cemented
spodic
horizon which does not contain enough amorphous iron to turn
redder on ignition
(in Podzols only)
Carbonati-
Having a soil solution with pH > 8.5 (1:1 in water) and HCO
> SO
>> Cl
(in Solonchaks
3
4
only)
Chloridi-
Having a soil solution (1:1 in water) with Cl >> SO
> HCO
(in Solonchaks only)
4
3
Cryi-
Having a
cryic
horizon within 100 cm of the soil surface
¤
IdentiÝcation of soil properties/materials in the Ýeld, further evidenced by laboratory analyses if
needed
¤
IdentiÝcation of the presence and kind of soil horizons
¤
IdentiÝcation of the vertical arrangement of horizons
¤
IdentiÝcation of the applicable WRB Reference Soil Group(s) in the WRB Key
¤
Final classiÝcation of the soil; considers the list of (ranked) qualiÝers as described in the following
paragraph for the example of a Ferralsol
The WRB as a Soil Correlation System
The World Reference Base has a modular (building-block) structure. The building blocks are
the uniquely deÝned qualiÝers discussed above; a sample set of qualiÝers and their deÝnitions are
given in Table 19.4. Once the Reference Soil Group is identiÝed, applicable qualiÝers deÝne
individual Soil Units. The following example classiÝes a Soil Unit in the Reference Soil Group of
the Ferralsols:
EXAMPLE
In Ferralsols the following qualiÝers have been recognized so far (in ranking order):
Strong expression qualiÝers:
¤
Gibbsic
>25% gibbsite in Ýne earth fraction, within 100 cm depth
¤
Geric
Having geric properties within 100 cm
¤
Posic
Having a zero or positive charge within 100 cm
Intergrade qualiÝers
(in the order of the key)
:
¤
Histic
intergrade with Histosols reference soil group
¤
Gleyic
intergrade with Gleysols reference group
¤
Andic
intergrade with Andosols reference group
¤
Plinthic
intergrade with Plinthosols
¤
Mollic
intergrade with Phaeozems
¤
Acric
intergrade with Acrisols
