Entic Grossarenic Alorthod PE
A representative soil profile of a sandy, siliceous, isohyperthermic Entic Grossarenic Alorthod
(Photo and comments courtesy of Stan Buol, NCSU.)
This profile was photographed in the state of Loreto, Peru SA. The site is in the Amazon River basin. A thin spodic horizon slightly above 200 cm, but dipping to below 200 cm to the right of the tape barely qualifies this profile as a Spodosol. Such soils are frequently associated with Quartzipsamments that have no spodic horizon or a spodic horizon that is deeper than 200 cm.
Spodosols and associated Quartzipsamments have been estimated to occupy as much as 10 percent of the Amazon basin with the greatest concentration in the Rio Negro basin watershed in Brazil. However, there are rather isolated occurrences where sandy textured parent material presumably deposited at point bar locations of the meandering river systems have change course throughout the western part of the Amazon basin.
Tropical forests vegetates such sites although vegetation is less dense than surrounding areas with finer textured soils. Indigenous people seldom select such sites for slash and burn cultivation and once cleared, burned and abandoned they are extremely slow to again vegetate. The presence of such sites can often be located because the white sandy material is dug and deposited in an attempt to improve trafficking in the wetter spots of the primitive roadways. The sand is the coarsest material locally available in the area that is devoid of gravel deposits. Coffee colored (black water) streams also are indicators of such soils in their watersheds.
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Entic Grossarenic Alorthods are the Alorthods that have a sandy or sandy-skeletal particle-size class from the mineral soil surface to the top of a spodic horizon at a depth of 125 cm or more and have less than 3.0 percent organic carbon in the upper 2 cm of the spodic horizon. These soils are not saturated with water for 20 or more consecutive days or 30 or more cumulative days in normal years and do not have an argillic or kandic horizon. They are common in the southeastern part of the United States. Most do or did support hardwood vegetation, but some have been cleared for crop production.
Alorthods are the Orthods that have accumulations of aluminum that are relatively high compared to the accumulations of iron. These soils formed predominantly in sandy deposits. The soils have low accumulations of iron either because of intensive leaching or because of parent materials that are low in iron. Alorthods normally have a thick albic horizon and an ochric epipedon. They are more common in areas of warm climates than in cool environments. In the United States, they occur mainly in the Southeast.
Orthods are the relatively freely drained Spodosols that have a horizon of accumulation containing aluminum, or aluminum and iron, and organic carbon. These are the most common Spodosols in the northern parts of Europe and in the United States. They formed predominantly in coarse, acid Pleistocene or Holocene deposits under a mostly coniferous forest vegetation. If undisturbed, Orthods normally have an O horizon, an albic horizon, and a spodic horizon and may have a fragipan. Some of these soils, however, have been mixed by the roots of falling trees or by animals and have a very thin albic horizon or no albic 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:
Entic Grossarenic Alorthod PE
A representative soil profile of a sandy, siliceous, isohyperthermic Entic Grossarenic Alorthod
(Photo and comments courtesy of Stan Buol, NCSU.)
This profile was photographed in the state of Loreto, Peru SA. The site is in the Amazon River basin. A thin spodic horizon slightly above 200 cm, but dipping to below 200 cm to the right of the tape barely qualifies this profile as a Spodosol. Such soils are frequently associated with Quartzipsamments that have no spodic horizon or a spodic horizon that is deeper than 200 cm.
Spodosols and associated Quartzipsamments have been estimated to occupy as much as 10 percent of the Amazon basin with the greatest concentration in the Rio Negro basin watershed in Brazil. However, there are rather isolated occurrences where sandy textured parent material presumably deposited at point bar locations of the meandering river systems have change course throughout the western part of the Amazon basin.
Tropical forests vegetates such sites although vegetation is less dense than surrounding areas with finer textured soils. Indigenous people seldom select such sites for slash and burn cultivation and once cleared, burned and abandoned they are extremely slow to again vegetate. The presence of such sites can often be located because the white sandy material is dug and deposited in an attempt to improve trafficking in the wetter spots of the primitive roadways. The sand is the coarsest material locally available in the area that is devoid of gravel deposits. Coffee colored (black water) streams also are indicators of such soils in their watersheds.
____________________________________
Entic Grossarenic Alorthods are the Alorthods that have a sandy or sandy-skeletal particle-size class from the mineral soil surface to the top of a spodic horizon at a depth of 125 cm or more and have less than 3.0 percent organic carbon in the upper 2 cm of the spodic horizon. These soils are not saturated with water for 20 or more consecutive days or 30 or more cumulative days in normal years and do not have an argillic or kandic horizon. They are common in the southeastern part of the United States. Most do or did support hardwood vegetation, but some have been cleared for crop production.
Alorthods are the Orthods that have accumulations of aluminum that are relatively high compared to the accumulations of iron. These soils formed predominantly in sandy deposits. The soils have low accumulations of iron either because of intensive leaching or because of parent materials that are low in iron. Alorthods normally have a thick albic horizon and an ochric epipedon. They are more common in areas of warm climates than in cool environments. In the United States, they occur mainly in the Southeast.
Orthods are the relatively freely drained Spodosols that have a horizon of accumulation containing aluminum, or aluminum and iron, and organic carbon. These are the most common Spodosols in the northern parts of Europe and in the United States. They formed predominantly in coarse, acid Pleistocene or Holocene deposits under a mostly coniferous forest vegetation. If undisturbed, Orthods normally have an O horizon, an albic horizon, and a spodic horizon and may have a fragipan. Some of these soils, however, have been mixed by the roots of falling trees or by animals and have a very thin albic horizon or no albic 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: