Agriculture Reference
In-Depth Information
and even contributed to study of soils as an independent discipline. Many of the concepts that
emerged were to be adopted later, and paved the way for new thinking in soil classiÝcation.
PROFILE-GENETIC APPROACHES TO SOIL CLASSIFICATION
AND RELEVANT SYSTEMS
The proÝle-genetic approach to soil classiÝcation implies that soil horizons should be analyzed
with due respect to their interdependence; in other words, the attention should be focused on the
system of these horizons that make up the genetic proÝle of soil. Unfortunately, after Dokuchaev,
this approach has never been fully realized in Russia, although it was taken into account in many
other soil classiÝcations. None of the ofÝcial classiÝcations, however, were based on the pro-
Ýle-genetic concept.
The Ýrst example of the elaboration of soil classiÝcation on the basis of internal soil parameters
in Russia is that of K.K. Gedroits in 1925 (Gedroits, 1966). The author was a well-known specialist
in physical chemistry. For decades he studied soil absorptive complex. He decided to develop a
soil classiÝcation system based on the parameters of the absorptive complex. He distinguished two
soil groups (with and without H
) and four types of pedogenesisÐchernozemic, solonetzic, pod-
zolic, and latheritic. K.K. Gedroits recognized that he did not have enough information to elaborate
on the working soil classiÝcation, but he believed in the future of this approach. His attempt should
be evaluated as a substantive approach to soil classiÝcation; but further data on soil absorptive
complex showed the severe limitation of this approach, and the impossibility of reÞecting real soil
diversity by only this parameter.
A more holistic approach to soil classiÝcation was proposed by S.S. Neustruev in 1926 (Neus-
truev, 1967). He produced a system of classiÝcation of pedogenic processes, rather than that of
soils. The same criteriaÐÑelementary pedogenic processesÒÐwere used about 50 years later by
I.P. Gerasimov (Gerasimov, 1975) for diagnostics and classiÝcation of soils. The problem of
ÑprocessÒ approach to soil classiÝcation in both cases is lack of information and speculative
character of understanding of soil processes. In later years, the processes were deÝned in terms of
products and, consequently, the ÑprocessÒ concept became an integral part of classiÝcation.
The most comprehensive soil classiÝcation system in the world based on proÝle-genetic
approach was proposed by M.A. Glazovskaya in 1966 (Glazovskaya, 1983). The system is strictly
hierarchical, in that there are three above-type levels: associations, generations (classes), and
families, and soil types are arranged in families in accordance with distinct rules. Lower categories
were traditionally preserved, as in the above-mentioned system of Ivanova-Rozov. Thus criteria for
the highest category of geochemical associations of soils were pH and soil features indicative of
redox conditions; members of the second category are differentiated by broad processes of organic
matter accumulation, formation of secondary minerals, translocation of substances, effects of
ground water, etc. The difference in composition of pedogenetic accumulations (humus, neofor-
mations, illuvial horizons, etc.) permit the speciÝcation of families within classes.
As is evident from this brief review, by the end of the 20
+
century, concepts were sufÝciently
well tested to develop a scientiÝc system that also has practical value. The development of soil
classiÝcation in Russia in the 1980s and 1990s is related to proÝle-genetic approach only. After
Soil Taxonomy (Soil Survey Staff, 1975) and the FAO-UNESCO map legend, it became increasingly
evident that the approach was rational, and clearly subscribed to by the global soil science com-
munity. This approach was actually deemed the basis of classiÝcation principles and schemes
developed by V.M. Fridland (Fridland, 1981, 1982)
th
The classiÝcation schemes suggested by L.L.
Shishov and I.A. Sokolov (1989; 1991) are also based on soil proÝle morphology, along with some
other substantive and dynamic characteristics of soils. This experience was used for elaborating
the new soil classiÝcation system of Russia.
.
