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Typic Haplogypsid, petrogypsic and landscape AE

A Typic Haplogypsid, petrogypsic from the interior of the UAE.

 

Typic Haplogypsids are the Haplogypsids that do not have have a gypsic horizon with its upper boundary within 18 cm of the soil surface. These soils do not have a lithic contact within 50 cm of the soil surface. In the United States they occur in Nevada, Arizona, and New Mexico.

 

The gypsic horizon is a horizon in which gypsum has accumulated or been transformed to a significant extent (secondary gypsum (CaSO 4) has accumulated through more than 150 mm of soil, so that this horizon contains at least 5% more gypsum than the underlying horizon). It typically occurs as a subsurface horizon, but it may occur at the surface in some soils.

 

This pedon has a petrogypsic horizon at a depth of 100 to 200 cm (130 cm in this pedon) and is identified as a "phase" in classification. In the UAE soil classification system, phases of soil taxa have been developed for those mineral soils that have soil properties or characteristics that occur at a deeper depth than currently identified for an established taxonomic subgroup or soil properties that effect interpretations not currently recognized at the subgroup level. The phases which have been identified in the UAE include: anhydritic, aquic, calcic, gypsic, lithic, petrocalcic, petrogypsic, salic, salidic, shelly, and sodic.

 

The petrogypsic horizon is a horizon in which visible secondary gypsum has accumulated or has been transformed. The horizon is cemented (i.e., extremely weakly through indurated cementation classes), and the cementation is both laterally continuous and root limiting, even when the soil is moist. Th e horizon typically occurs as a subsurface horizon, but it may occur at the surface in some soils.

 

Haplogypsids are the Gypsids that have no petrogypsic, natric, argillic, or calcic horizon that has an upper boundary within 100 cm of the soil surface. Some Haplogypsids have a cambic horizon overlying the gypsic horizon. These soils are commonly very pale in color. They are not extensive in the United States. The largest concentrations in the United States are in New Mexico and Texas. The soils are more common in other parts of the world.

 

Gypsids are the Aridisols that have a gypsic or petrogypsic horizon within 100 cm of the soil surface. Accumulation of gypsum takes place initially as crystal aggregates in the voids of the soils. These aggregates grow by accretion, displacing the enclosing soil material. When the gypsic horizon occurs as a cemented impermeable layer, it is recognized as the petrogypsic horizon. Each of these forms of gypsum accumulation implies processes in the soils, and each presents a constraint to soil use. One of the largest constraints is dissolution of the gypsum, which plays havoc with structures, roads, and irrigation delivery systems. The presence of one or more of these horizons, with or without other diagnostic horizons, defines the great groups of the Gypsids. Gypsids occur in Iraq, Syria, Saudi Arabia, Iran, Somalia, West Asia, and some of the most arid areas of the western part of the United States. Gypsids are on many segments of the landscape. Some of them have calcic or related horizons that overlie the gypsic horizon.

 

For more information about describing soils, visit:

www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052523...

 

For additional information about soil classification using Soil Taxonomy, visit:

sites.google.com/site/dinpuithai/Home

 

For more information about soil classification using the UAE Keys to Soil Taxonomy, visit:

agrifs.ir/sites/default/files/United%20Arab%20Emirates%20...

 

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Uploaded on December 27, 2021