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Typic Petrogypsid, shallow and landscape AE

A shallow Typic Petrogypsid from the interior of the UAE.

 

These shallow mineral soils that are less than 50 cm deep (from the soil surface) to a root-limiting layer (petrogypsic or petrocalcic horizon, or a paralithic contact) excluding soils that are in a Lithic subgroup.

 

Petrogypsids are the Gypsids that have a petrogypsic horizon that has its upper boundary within 100 cm of the soil surface. These soils occur in very arid areas of the world where the parent material is high in content of gypsum. When the petrogypsic horizon is close to the surface, crusting forms pseudohexagonal patterns on the soil surface. Petrogypsids occupy old surfaces. In Syria and Iraq, they are on the highest terraces along the Tigris and Euphrates Rivers. These soils are not extensive in the United States but are extensive in other countries.

 

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 cemented through indurated cementation classes), and the cementation is both laterally continuous and root limiting, even when the soil is moist. The horizon typically occurs as a subsurface horizon, but it may occur at the surface in some soils (foreground).

 

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 24, 2021