Andisols

( Andic of the property derived from Japanese to do, black soil ' and the Latin sol, soil ') Andisol is one of the twelve main groups of the USDA soil classification, it corresponds to the FAO soil classification and World Reference Base for Soil Resources about the group of Andosols. It comprises mainly volcanic soils. Subordinate may, under certain conditions of weathering nichtvulkanischem starting material with a high proportion of aluminosilicates a Andisol arise.

Definition

The typical feature of Andi Sole is a predominance of weathering only little conversion of transported minerals such as allophane or aluminum -humus complexes. Does not matter in the formation of the subsurface, the rests of the ground, the decisive factor is alone that 60 % of the upper 60 cm have the characteristic andic property (see below). This soil horizons are not taken into account with an organic content of more than 25%. Specifically, the definition and delimitation to other soil types includes numerous other criteria.

In the USDA soil classification Andi sols are defined as soils with andic properties in more than 60 % of the floor thickness either

  • Within the top 60 cm of a mineral or an organic base with andic properties, depending on which is closest to the surface, if any of the following occurs hardened soil horizons not hard cemented soil horizon ( densic )
  • Verkieselungshorizont ( duripan )
  • Calcification horizon ( petrocalcic )

Or

  • Between the surface of a mineral or an organic base with andic properties, depending on which is closest to the surface, and one of the preceding hardened soil layers within a depth of 60 cm.

The andic property

The andic property is defined in the USDA soil classification as a property of soils with a share of less than 25% by weight of organic carbon and one or both of the following criteria:

  • In the fine fraction of the following criteria at least two percent ( Alox ½ Feox ) content (see below)
  • Most 0.9 kg/dm.sup.3 storage density
  • At least 85 percent phosphate retention
  • At least 0.4 % ( Alox ½ Feox ) content and at least 30 % volcanic glass in the grain sizes from 0.02 to 2.0 mm
  • At least two percent ( Alox ½ Feox ) content and at least 5 % volcanic glass in the grain sizes from 0.02 to 2.0 mm
  • Between 0.4 and 2 % ( Alox ½ Feox ) content and a glass content of between 5 and 30% in grain sizes from 0.02 to 2.0 mm, and the in a diagram of the two variables ( Alox ½ Feox ) content glass content in a particular chart area falls.

This Alox and Feox is the aluminum and iron content in the acid oxalate-extractable percentage of dried at 105 ° C fine earth (0-2 mm).

Andic the property, depending on the aluminum and silicon content in silandic and aluandic further subdivided.

Properties

Andi Sole develop from volcanic ash, have a high amount of volcanic glasses and because of their emergence often a considerable thickness. If deposit with time several layers one above the other, is typical soil profiles with brown to black colored oxides; the older, then Paläosol said layers lie naturally always among the younger deposits.

Andi Sole distinguished by the fact that they can store large amounts of water and are also very fertile; they are for this reason, wherever possible, used for agriculture. However, they are very little erosion resistant. The pH is neutral.

Occurrence

Andi Sole are world about 900,000 square kilometers, or just under one percent of the ice-free land area and always found near volcanoes, such as on the Pacific coast of America, New Zealand, Japan, Indonesia, Iceland and some smaller islands such as the Canary Islands.

Classification

It distinguishes seven suborders:

  • Aquand: a Andisol with near-surface, high groundwater levels during most of the year
  • Cryand: more or less well drained Andisol in cold climates
  • Torrand: more or less well drained Andisol in dry air
  • Xerand: more or less well drained Andisol in climates with Mediterranean moisture conditions and cool, temperate or hot temperature conditions
  • Vitrand: more or less well- drained, coarse Andisol
  • UStand: more or less well drained Andisol in semihumidem climate to semi-arid climate
  • Udand: more or less well drained Andisol in wet climates.
World Reference Base for Soil Resources Aluminium Cementation (geology) Petrifaction Mediterranean Basin
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