Russian Soil Classification
The first comprehensive Russian soil classification system was
developed in 1895 by Sibirtzev, who followed Dokuchaev’s concept
of soil formation (genesis). The origin of soil, regarded as a natural
body, was linked to external characteristics related to the main
soil-forming factors (e.g. climate, vegetation, relief, parent material,
time) and internal, newly-developed characteristics (e.g. structure,
consistency, compaction, pH, humus contents; exchangeable
cations). Both groups of soil characteristics are interrelated and are
used to define a soil body. The soil is described by a series of genetic
horizons and profiles, which are then the basis for classification.
In 1982, Fridland developed a three-dimensional system of soil
classification as the basis for the legend of a country-wide soil
inventory of Russia [30]. The system was based on three domains:
soil characteristics, soil hydro-thermic regimes and petro-chemical
composition of the parent material. The full name of the soil type
is a combination of all three domains (e.g. Podzol-Permafrostpolymixed sandy).
Extent of permafrost affected soil
Discontinuous (37%)
Seasonal and
Non-freezing (35%)
Sporadic (14%)
Continuous (14%)
Extent of permafrost-affected soils (in percent) in the permafrost zones of
Russia: sporadic (<50%); discontinuous (50-90%) and continuous (90%). (VS)
Northern soil
Distribution of soil orders in Russia
(total soil area: 16 million km2)
Lithozems, Halomorphic &
Low-humic
accumulative-calcareous* (1%)
Al-Fe-Humic (23%)
Alkaline clay-differentiated (1%)
Volcanic (1%)
Shallow weakly-developed (2%)
Alluvial (3%)
Cryozems (4%)
Sod organic-accumulative (6%)
Peat (7%)
Gleyzems (16%)
Metamorphic (10%)
Humic-accumulative (10%)
Texture-differentiated (16%)
* Aggregated to a single class due to limited extent.
(VS)
The soil characteristics domain consisits of the following
hierarchical categories: trunk > division > type > subtype > genera
> species > variety > phase.
•
Soil Division
Permafrost zones
Sporadic
Discontinuous
Continuous
173.5
AI-Fe-humic
53.6
88.4
Texture differentiated
47.0
7.2
1.0
GIyzems
18.4
20.3
199.9
Humic-accumulative
11.0
1.6
0.5
Metamorphic
32.2
32.0
56.0
Sod organic-accumulative
11.6
43.2
45.0
10.5
Peat
36.0
8.8
Cryozems
<0.1
15.3
59.0
Total Soil
209.8
216.8
545.4
Area of the Zone
223.7
227.1
582.2
Divisions within a trunk reflect the major soil forming process
responsible for the principle features of the soil profile (horizon
sequence).
•
Type is a subdivision of soil division characterized by a specific
sequence of soil horizons in a profile having common soilforming process (e.g., organic matter input and decomposition,
mineral material transformation, migration and accumulation).
•
Subtype reflects a modification of the major soil forming
process making the soil transitional to another soil type.
•
The remaining lower-level categories of classification distinguish
specific soil features (e.g. chemical, physical, mineralogical, etc.).
The hydro-thermic regimes domain describes soil through
water and temperature characteristics in three levels: classes,
subclasses and categories. These levels consider factors such as the
presence of permafrost, thawing depth, duration of the frozen state
and accumulated temperature above zero. The permafrost level
is characterized by the presence of permafrost and a maximum
thawing depth of 100 cm. This hydro-thermic regime is common
for the zone with continuous permafrost (see figure above-right).
The long-term seasonally frozen class is characterized by a freezing
depth of 100-300 cm with the soil remaining frozen for more than
6 months. This condition is common for the zones of discontinuous
and sporadic permafrost (see page 20).
The petro-chemical composition domain describes the
characteristics of the parent material (e.g. minerals, texture,
chemical composition).
Cryozems. A peaty Cryozem from the European Russian Arctic. The
presence of many small horizontal cracks indicates an unstable
(thyxotropic) soil mass. (DK)
Area (million ha) of permafrost-affected soils in Russia. (VS)
Cryozems. The concept of Cryozems in the Russian classification
is associated to the presence of permafrost and where intensive
cryoturbation has led to a totally mixed soil (i.e. no horizons are
visible apart from a shallow, peaty layer on the surface). The extent
of Cryozems is widespread in the zone of continuous permafrost
and less in the other zones.
Trunks reflect soil forming process with distinctions made for
soils formed under stable geological conditions (postlithogenic),
soil formation linked with sedimentation (synlithogenic) or
dominated by accumulation of organic matter as represented
by peat (organogenic).
•
42
Russia is exposed to the Arctic Ocean and has a severe cold climate
causing extensive permafrost beneath nearly 68% of the territory. Six
soil divisions dominate the permafrost zones in Russia.
Sod-organic-accumulative. Cryoturbation is a common feature in
permafrost-affected soils. A calcareous sod-organic-accumulative
permafrost soil in Western Siberia. (AL)
Texture-differentiated permafrost soils are more commonly
found in the sporadic permafrost zone where the climate is slightly
warmer. These soils have a strongly bleached topsoil and clay-rich
(argic) B horizon with an irregular or broken boundary due to the
presence of deep tonguing of the bleached material in to the B
horizon and below. The tonguing is a relict of frost cracking.
Gleyzems permafrost soils occupy a considerable area in the
zone of continuous permafrost. These are poorly drained soils
having excess water and suffering from a deficiency of oxygen (e.g.
indicated by olive and blue colours in the soil profile). The lack of
oxygen reduces the rate and degree of organic matter decomposition
leading to the accumulation of peat and muck (organic-rich) horizons
in the topsoil. Ice-rich permafrost is commonly found within the
upper 100 cm.
Metamorphic permafrost soils are common throughout all
permafrost zones, especially where the permafrost is continuous.
These soils are identified by a differentiation in colour or structure.
The intensity of biological activity is low as the duration of the frostfree period is short, which favours the accumulation of partially
decomposed plant residues in the peat, peaty-muck and litter
horizons. Permafrost is usually observed within the upper 100 cm.
Cryozem. A typical Cryozem from the taiga of East Siberia. This soil is
widespread throughout Central and Northern Siberia and in Northeastern
Eurasia. The high ice content of the soil, visible at the base of the profile,
reduces the drainage and leads to water logging above the permafrost
table during the thawing period (indicated by the darker colour below
50 cm depth). (DK)
Aluminium-Iron-Humic permafrost soil (Al-Fe-Humic),
especially common in continuous permafrost. Coarse textured,
well drained and exhibits an accumulation of iron-aluminium and
organic compounds in subsurface horizon. The bleached topsoil
often associated with this type of soil is not always present. The
permafrost has low ice content and appears within 2 m of the
surface. Cracking and sorting are intensive.
Soil Atlas of the Northern Circumpolar Region | Soil Classsification
Sod-organic-accumulative permafrost soils tend to be
more prevalent in the discontinues and continuous permafrost
zones. These soils are characterised by a dark-coloured humus
horizon. The formation of this horizon is supported by the presence
of calcareous rock debris that maintains a neutral pH. These soils
have mostly dry permafrost.
Peat-frozen soils are more commonly found in the zone of sporadic
permafrost. Deep peat deposits (>50 cm) occupy relatively small
areas in other permafrost zones due to low temperatures, limited
vegetation production and shallow permafrost table. Peat frozen soil
is often found in patterned ground in association with mineral soils
and stone polygons. The composition of the peat depends on the
nature of the vegetation remains, chemistry of ground water, the
degree of decomposition and content of mineral soil.