Capability of Soil Taxonomy (2014) compared to updated WRB (2015) in describing Lut Desert soils

Abstract

Soil classification is useful to better understand and manage soils. The objective of the present research was to compare the capability of Soil Taxonomy (2014) and WRB (2015) systems to describe and classify soils in Lut Desert. Marginal and central parts of Lut with typical aridic/thermic and extreme aridic/hyperthermic soil moisture/temperature regimes were selected. Twelve representative pedons on alluvial fan, plain, rock pediment, Gandom Beryan lava plateau, and playa were described and sampled. Results of the study clearly showed that the WRB system was more capable to reflect soil forming processes. However, it is recommended that anhydritic qualifier to Solonchaks, Solonetz, and Gypsisols; aquatic qualifier to Solonchaks and Solonetz; and abruptic, leptic, and paralithic qualifiers to Solonchaks be added. The ST system has not been successful in expressing soil forming processes because this classification system considers only two great groups for saline soils and gives priority to Salids in comparison to the other suborders of Aridisols. That is why Petrosalids, Gypsisalids, Natrisalids, and Argisalids great groups and Anhydritic Natrisalids, Anhydritic Argisalids, Anhydritic gypsisalids, Anhydritic Petrosalids, Calcic Natrisalids, Calcic Argisalids, Calcic Gypsisalids, Natric Petrosalids, Natric Haplosalids, Natric Gypsisalids, Petrogypsic Petrosalids, and Epipetrosalic Aquisalids subgroups are suggested to be added to Soil Taxonomy system. Meanwhile, definition of anhydritic horizon, considering textural difference in strongly contrasting particle size classes of family level, and aquic conditions in playa were among the strong points of Soil Taxonomy. It is also suggested to remove (or adopt) colour (Hue) requirement of anhydritic horizon in ST system.

Keywords

• saline soils
• gypsiferous soils
• anhydritic horizon
• paralithic qualifiers
• aquic conditions