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Classification, Properties, and Management of Aridisols

The Orthid Suborder

Aridisols Slide 37

In the 1975 edition of Soil Taxonomy, the Orthid Suborder was a catch-all class of soils that in the recent 7th edition have been divided among seven Suborders, mostly among the Salids, Durids, Gypsids, Calcids, and Cambids.

Aridisols Slide 38

The six Great Groups of the obsolete Orthid Suborder were differentiated by their subsurface diagnostic horizons that now distinguish them at the higher, Suborder level.

Aridisols Slide 39

Salorthids, one of the original six Orthid Great Groups, were soils with salic horizons and a groundwater table above one meter for one month or more in most years. These soils are now classified as Aquisalids and normally occur in depressions and closed basins that are extremely difficult to drain. Because of this, these soils with extreme salt content are rarely reclaimed for agricultural use. Salids with better drainage are classified as Haplosalids and may be candidates for reclamation.

Aridisols Slide 40

Paleorthids were Orthids with petrocalcic horizons within 1 meter of the soil surface. These soils are now classified as Petrocalcids. The presence of this cemented horizon at a shallow depth makes most Petrocalcids unsuitable for agriculture unless the petrocalcic horizon can be removed.

Aridisols Slide 41

Soils with duripans within 1 meter of the surface used to be classified as Durothids. These soils are now classified as Haplodurids. The duripan commonly occurs at depths less than 50 cm and because of this, Haplodurids are generally not developed for agriculture. These soils are best suited for use as rangelands.

Aridisols Slide 42

Gypsiorthids were the class of soils with a gypsic or a petrogypsic horizon within 1 meter of the soil surface. These soils are now classified as Petrogypsids, Natrigypsids, Argigypsids, Calcigypsids, and Haplogypsids (refer to the 9th edition for more detailed information). Irrigation water must be closely monitored on these soils because gypsic horizons can be partially dissolved, causing subsidence and unfavorable topographic changes.

Aridisols Slide 43

Calciorthids were Orthids with calcic horizons and lime throughout the profile. They are now classified as Haplocalcids. The only horizons normally present are an ochric epipedon and a calcic horizon. High carbonate levels and high soil pH commonly cause iron and phosphorus deficiencies in these soils.

Aridisols Slide 44

Camborthids were soils with a cambic horizon and generally lack all other subsurface diagnostic horizons. These soils are now classified as Aquicambids, Petrocambids, Anthracambids, and Haplocambids. The last two classes of soils have few constraints for irrigated agriculture since they lack cemented horizons, have good drainage, and do not contain excessive amounts of soluble salts, gypsum or carbonates.

Introduction to Aridic Soils | Soil Taxonomy | Introduction to Soil Horizons | The Horizons | Suborders and Great Groups | Argid Suborder | Orthid Suborder | Subgroups | Families | Non-Aridisols | Irrigation | Saline Soils | Sodic and Saline-Sodic Soils | Final Considerations

Last revised: 24 November 2003
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