PETROGYPSID, TYPIC
Soil profile: A Typic Petrogypsid from north-central UAE.
Center: Typical landscape associated with Petrogypsid soils.
Soil feature: Various gypsum crystals on soil surface.
Petrogypsids are the Gypsids that have a petrogypsic or petrocalcic 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.
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.
Aridisols, as their name implies, are soils in which water is not available to mesophytic plants for long periods. During most of the time when the soils are warm enough for plants to grow, soil water is held at potentials less than the permanent wilting point or has a content of soluble salts great enough to limit the growth of plants other than halophytes, or both. The concept of Aridisols is based on limited soil moisture available for the growth of most plants. In areas bordering deserts, the absolute precipitation may be sufficient for the growth of some plants. Because of runoff or a very low storage capacity of the soils, or both, however, the actual soil moisture regime is aridic.
For more information about soil classification in the UAE, visit:
"United Arab Emirates Keys to Soil Taxonomy" and "ICBA News"
PETROGYPSID, TYPIC
Soil profile: A Typic Petrogypsid from north-central UAE.
Center: Typical landscape associated with Petrogypsid soils.
Soil feature: Various gypsum crystals on soil surface.
Petrogypsids are the Gypsids that have a petrogypsic or petrocalcic 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.
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.
Aridisols, as their name implies, are soils in which water is not available to mesophytic plants for long periods. During most of the time when the soils are warm enough for plants to grow, soil water is held at potentials less than the permanent wilting point or has a content of soluble salts great enough to limit the growth of plants other than halophytes, or both. The concept of Aridisols is based on limited soil moisture available for the growth of most plants. In areas bordering deserts, the absolute precipitation may be sufficient for the growth of some plants. Because of runoff or a very low storage capacity of the soils, or both, however, the actual soil moisture regime is aridic.
For more information about soil classification in the UAE, visit:
"United Arab Emirates Keys to Soil Taxonomy" and "ICBA News"