Geoscience Reference
In-Depth Information
The dominant human infl uence comprises the deposition of organic wastes and
irrigation and cultivation of loose powderlike to fi ne granular material that would
not be denoted as soil under natural conditions. As a result of continued manuring
over long periods of time, the surface horizon has features which may reach to
depths greater than that of the humus A horizon in soils evolved under the natural
conditions of that region. With evidence of old cultivation and modifi cation of the
relief by farmers, the physical properties of these soils are usually favorable in spite
of their earlier less favorable chemical characteristics. Today, systematic fertiliza-
tion and careful management of soil pH sustain the fertile character of the majority
of Anthrosols except those in the semiarid zone with a high salinization hazard.
They include soils of national classifi cation systems: Plaggen soils, Paddy soils,
Oasis soils, Terra Preta do Indio, Agrozems, Terrestrische anthropogene Böden, and
Anthroposols.
Technosols denote soils that originated by technical skill of humans; the term has
its roots in the Greek
technikos
meaning skillfully made. The parent material is
selected in accordance to the aim decided by man. There is no profi le development
except for some humus-containing soil occasionally deposited on the surface as a
top layer covering the dumped material. This top layer enables the revegetation of
materials fi lling in surface mines or covering refuse dumps, oil spills, coal fl y ash
deposits, and similar by-products of technological processes. Technosols were orig-
inally not recognized as a RSG. But the permanent increase of their area and their
extensive infl uence upon the environment required their special introduction as a
separate RSG.
3. The third set is formed by soils with a severe limitation to rooting. There are two
RSGs in this set:
Cryosols
and
Leptosols
.
Cryosols are mineral soils formed in permafrost where water, if present, occurs
as ice, like small ice lenses or as small honeycomb structures. The name was derived
from the Greek
kryos
meaning cold. Parent rock was formed by a variety of loose
unconsolidated materials like glacial and colluvium sediments deposited at the base
of slopes or by wind and river sediments deposited in earlier geological epochs. The
thickness of parent material is highly variable and is associated with a sparse tundra
vegetation and lichen coniferous or mixed forests. The soil profi le is composed of
an active surface horizon that thaws every summer and protects the underlying per-
mafrost. Human activities like oil and gas mining or introduction of agriculture,
transport constructions, as well as natural changes lead to material fl ow and mixing
(cryoturbation) accompanied with erosion of thawed soil, volumetric change, ther-
mal cracking, and great surface morphological changes. The national classifi cations
use the terms Cryozems, Cryomorphic Soils, or Polar Desert Soils. They are as
Gelisols in US Taxonomy Orders.
Leptosols are very shallow gravelly soils overlaying a continuous rock or gravel
layer with less than 10 % of fi ne weathered material or with continuous hard rock
within 25 cm from the soil surface. Provided that their stony character persists, they
exist in all climatic zones including permafrost. They are widespread in mountains.
The name has its roots in the Greek
leptos
meaning thin. Due to their abundant
