Agriculture Reference
In-Depth Information
classiÝcation had to be developed. Theoretically, there were three possible ways to achieve this
purpose:
1.
To reÝne and supplement the classiÝcation of 1977 without considerable changes to its basic
principles
2.
To adapt Soil Taxonomy (the U.S. system of soil classiÝcation) to Russian conditions
3.
To develop a new classiÝcation that would have its own principles and would combine the
advantages of both above-mentioned classiÝcation systems
The special commission on soil classiÝcation at the USSR Soil Science Society, which started
its work in 1979, decided that the new classiÝcation should be based on the principles suggested
by V.M. Fridland (Fridland, 1981). The rationale of this system is summarized as follows: the
proÝle-genetic component of soil classiÝcation is based on the morphology of soil proÝles and on
soil properties that are considered the results of pedogenic processes. To realize this basic principle,
the nomenclature and diagnostics of most important genetic soil horizons had to be developed.
Many of these horizons were not separately distinguished in previous classiÝcation systems, and
this became the Ýrst challenge.
The new ideas introduced in the Russian Soil ClassiÝcation System (Shishov et al., 2001)
distinguish this system from both the ClassiÝcation of Soils of the Soviet Union and Soil Taxonomy.
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First, the new classiÝcation is a proÝle-genetic system. Therefore, in contrast to its predecessors,
the highest taxonomic categories of this classiÝcation (soil orders and soil types) are distinguished
on the basis of analysis of a conjugated system of genetic soil horizons that make up the soil
proÝle. In turn, the deÝnitions of these horizons are based on the integrity of substantive soil
features and properties, dictated by pedogenic processes. Environmental agents, including climatic
parameters (soil water and temperature regimes), are virtually excluded from the diagnostics of
most soil taxa.
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Second, special attention is paid to anthropogenically (agrogenically and technogenically) trans-
formed soils. These soils are considered the results of soil evolution under the impact of human
activities. Several stages of this evolution are distinguished. Thus, taken together with correspond-
ing natural soils, anthropogenically transformed soils form evolutionary sequences (from natural
soils to transformed natural-anthropogenic soils and, Ýnally, to nonsoil surface formations). The
reverse trend of soil evolution after the release from anthropogenic impact is also possible in some
cases (the restoration of natural soils from anthropogenically transformed ones). The classiÝcation
position of anthropogenically transformed soils does not take into account the goals and character
of human-induced impacts on soil and the level of soil fertility; it is fully dictated by the morphology
of the soil proÝle (Tonkonogov and Shishov, 1990; Lebedeva et al., 1996b). The ClassiÝcation of
Soils of the Soviet Union considered some of such soils only in the context of the degree of soil
cultivation and the character of soil transformation upon irrigation. At present, Soil Taxonomy
(Soil Survey Staff, 1999) does not separate anthropogenically transformed soils into a special
category, except for very strongly transformed soils (Lebedeva et al., 1996a), though the sugges-
tions on the inclusion of the order of Anthrosols into this classiÝcation is being discussed.
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Third, the new classiÝcation system of the soils of Russia is an open system; i.e., it provides a
means of introducing new soils into it, independently of their position in the system of geographical
zones and subzones and of environmental conditions. In this context, it is closer to Soil Taxonomy
than to the previous ofÝcial classiÝcation of the Soviet Union.
In spite of the fact that the new classiÝcation system is formally limited by the territory of
Russia, the proÝle-genetic approach to soil classiÝcation allows us to expand the system; in the
future, it can be transformed into the classiÝcation of soils of the world.
The system of diagnostic soil horizons and soil properties has been specially developed for the
diagnostics of soil types and subtypes. A particular combination of soil horizons serves as the basis
for separation of soil orders and soil types. Qualitative peculiarities of soil horizons (genetic soil
features) that are not taken into account at the type level specify the separation of soil subtypes.
