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from the surface horizons. Hydrogen and aluminium ions appear on
the exchange complex. Only the B horizons remain alkaline. Nowadays
these soils are grouped under Glossalbic Solonetz .
Solonetz and Solods are rarely cultivable and are often left to
extensive pasture.
In the WRB, the classification of subtypes is done by considering
accessory characteristics, particularly,
￿ morphology (Albic, Humic, Histic, Vertic, etc.),
￿ texture (Arenic, Siltic, Clayey, etc.),
￿ hydromorphy (Gleyic, Stagnic, etc.),
￿ chemistry (Gypsic, Chloridic, Sulphatic, Calcaric, etc.).
13.5.3 Groupings in Soil Taxonomy
Soil Taxonomy does not group saline soils separately. It considers that
salinity corresponds to a property that may occur in various Orders.
Therefore it is necessary to concern ourselves with the following
diagnostic horizons:
￿ Salic horizon that contains salts more soluble than gypsum ,
￿ Natric horizon , in which is found columnar structure, ESP >
15 or a value greater than 1 for the ratio [(Mg + Na)/(Ca +
exchangeable acidity)]. But our summarized definition is only
approximate,
￿ Gypsic horizon that contains gypsum precipitated in situ ,
￿ Petrogypsic that, in addition, is hardened,
￿ Also the adjective halic must at times be used which, in
Hal-aqu-epts for example, signifies ESP > 15.
Saline soils are found in various Orders, especially: Inceptisols
(immature soils), Entisols (scarcely developed soils), Aridisols (soils of
arid regions) and Alfisols (argilluviated soils). Presence of salts appears,
as the case may be:
￿ at the Suborder level, for example Sal-ids (with salic horizon) or
Gyps-ids (with gypsic or petrogypsic horizon),
￿ at the Great Group level, as for example in Sal-orth-ids
(Solonchaks), Natr-arg-ids (Solonetz) or Gypsi-arg-ids,
￿ At the Subgroup level, for example in Sodic Haplo-calc-ids, Sodic
Psamm-aqu-ents, Sodic Calci-xer-epts, etc.
It is difficult to account for salinity when it affects Mollisols (Rogel
et al . 2001a). For finding all these names, refer to Chapter 4 (§ 4.3).
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