Toward a
Comprehensive Soil
Classification System
Charles W. Finkl
Institute of Coastal Studies
Nova University
INTRODUCTION
The rapid growth of specialized
disciplines, as seen in the natural
sciences over the last several decades, has fostered new and diverse
vernaculars. As new information is
gained from closer study of natural
realms, additional terms are needed
to describe an increasing array of
recorded phenomena. Advances in
the geological sciences have, for example, contributed to a burgeoning
vocabulary. The 1980 edition of the
Glossary of Geology (American
Geological Institute) contains 36,000
terms, about 3,000 more than the
1972 edition . These additions reflect
changes in the geosciences over the
last decade, especially advances in
fields dealing with plate tectonics,
remote sensing, igneous petrology,
paleomagnetism, and biostratigraphy. Many recently coined terms are
appropriate and useful. Others will
not stand the test of time and will
fade away. Soil scientists as a collective body are perhaps also falling
unwittingly into a morass of scientific jargon. This terminological bottleneck is particularly evident in the
field of soil classification where there
exists a multiplicity of terms for describing soil units. This situation
presents an imposing problem for
geographers in particular, but geologists, ecologists, and environmental scientists also have cause for
concern.
The development of new soil
classification systems and revisions
of old ones is a global phenomenon
(1), not a local situation where one
or two nations have brought updated versions on line. The revolution that is taking place in soil clas-
41
sification probably will continue. Just
how well geographers and others
cope with a multitude of soil taxonomies may depend on their ability to rationalize cultural overtones
in the scientific arena .
CHANGING TAXONOMIES
In the early part of the 20th century, physical geographers and soil
scientists shared many common interests. Both groups investigated with
equal vigor the relationships between soils, landforms, and vegetation. Results of research focusing on
problems of soil erosion, conservation, soil mapping, land use, archaeology, and geography appeared in
geographical journals as well as in
the soil science literature (2) . Curtis
Fletcher Marbut, Chief of the Soil
Survey Division of the U.S. Department of Agriculture for many years,
was also a founding member and a
president of the Association of
American Geographers (1924-1925).
Such close ties between the two
disciplines left a legacy of scientific
terminology in the United States that
was comprehensible to both parties.
Much of that changed, however, with
the publication of Soil Taxonomy (3)
in 1975, the new official soil classification system for the United States
Department of Agriculture. Podzols,
Gray Wooded soils, and laterites
were respectively replaced, in part,
by great groups of Spodosols
(Cryorthods, Fragiorthods, Haplorthods) , Alfisols (Eutroboralfs), and
Oxisols (Acrorthox) . Many of the
principal old terms, which were derived from folk names indicative of
some distinctive property of the soil,
were dropped . Podzols, for exam42
pie, were widely known as acid ashy
gray sands over dark sandy loams,
the name being derived from the
Russian terms pod (beneath) and zol
(ash) . They were supplanted by new
names intended to be more precise
and meaningful. To American soil
scientists that change-over was a
gradual process involving several
experimental approximations (4) that
preceeded the present version published as U.S.DA Handbook No. 436
(Soil Taxonomy).
Many geographers were undoubtedly jolted by the complexity
of Soil Taxonomy and the apparently rapid phase-out of older systems. The loss of a familiar pedological terminology, which had
gained wide acceptance, lead some
to think that it was easier to "fight
than switch" (5) . Soil scientists have
lauded the merits of Soil Taxonomy
but in spite of their efforts to convince other professionals that it is
easier to "switch than fight" (6), there
is still resistance to change. Even
though there have been numerous
attempts to i ntroduce the new
American system of soil classification in palatable form (7), many have
found terms like Grossarenic Paleaquult, Pachic Ultic Haploxeroll, and
Paralithic Vertic Ustrochrept to be
cumbersome and distasteful. To
some, these terms do not sound the
way names of soils should sound,
but this is hardly a valid criticism of
the system. Questions like "What is
wrong with names like Chernozem,
Podzol, Rendzina, Andosol, and bog
soil, anyway?" remain common
among those outside of the soil
fraternity . Most geographers and
geologists still retain a basic notion
as to what these terms mean, or at
least they think they do. With time
comes change and hopefully some
degree of progress. So, if American
geographers just learn the new soil
taxonomy, all will be right with the
world , i.e., with the world of soil.
THE CHALLENGE OF
NOMENCLATURE AND SOIL
CORRELATION
For scientists working primarily in
the United States and for those who
do not require much detailed information about so ils elsewhere, the
new soil taxonomy will meet their
needs. The situation becomes less
comfortable however, when global
or regional soil patterns are relevant
to, or indeed the very object of,
study. The investigation of soil distributions from an intercontinental
point of view or even on an international basis can be a nomenclatural challenge that wears down the
grit of even the most hardy.
Consider for a moment the complexity of the situation facing today's geographers. Serious regional
studies of North American soils must
eventually deal with the different
systems employed by the United
States (1), Canada and Mexico (8) .
Most countries in South America
apply the FAO/ UNESCO legend although some nations such as Brazil
(9) have their own independent soil
taxonomy. In Western Europe the
situation is rather more complex
where England and Wales (10), West
Germany (11), and Belgium (12) , for
example, each have a different system of soil classification. In France,
two systems are frequently applied
(13) . Russian systems of soil classi-
fication (14) apply to most of northern Asia while other taxonomies are
applied in southern Asia, the Indian
subcontinent, and the Far East (15).
Australia , unlike most developed
countries, does not maintain a national soil survey . The Northcote
classification (16) is applied on a
continental basis although names of
soils from previous systems can still
be used. The Northcote system is
alpha-numerical but it is sometimes
more convenient to discuss a particular calcareous red earth than a Um
5.51 principal profile form. Several
taxonomic systems are in force on
the African continent making it a
real potpourri of soil classification .
The French system , with modifications, is still widely used in parts of
equatorial Africa and in some of the
former colonies. The FAO/ UNESCO
legend is followed throughout much
of the Middle East and a few nations
such as South Africa have distinctive soil taxonomies of their own
(17). Still other countries (e.g ., Costa
Rica and Venezuela) retain vestiges
of the former U.S. system. Even island nations such as New Zealand
(18) and Japan (19) have independent national soil taxonomies.
Although the FAO/ UNESCO soil
legend is followed in many parts of
Central and South America, and also
parts of Africa, it is not, strictly
speaking, a classification system. It
is mainly used as a guide in the
preparation of soil maps. Of the
many world soil maps that are available, perhaps the best known are
those prepared by the U.S. Soil Conservation Service (SCS) and FAO/
UNESCO. The SCS world maps are
usually seen at textbook scale,
43
whereas the FAO sheets are printed
at a scale of 1:5,000,000.
It should also be noted that there
are about as many special soil classification schemes (20) as there are
concepts of soil (21). Most special
purpose classifications focus on
some inherent pedological property
such as salinity, mineralogy, soil reaction (pH), and micromorphology;
or they consider selected attributes
having practical significance to engineering or some other practical
field such as pedogeochemistry. Regional classifications have been developed for polar and equatorial soil
zones (22) because these soils are
quite different from mid-latitude varieties which constituted the taxonomic data base for many systems.
Such a number of soil classification systems understandably leads
to confusion, befuddlement, and
even rage on the part of those trying
to make comparative studies. Specialists who pttempt to determine
equivalence between soil units, frequently find the job to be of nightmarish proportions because so few
terms are synonymous.
DISCUSSION
The decision to adopt one taxonomy as "the system" for describing the world's soils might be a satisfying gesture to a particular interest
group, but it hardly meets the need
for a universal or comprehensive
system . Classification systems have
been developed in the geological,
biological, and botanical sciences
which permit a rational taxonomical
organization of rocks, animals, and
plants (23). The unique properties of
soils, which are due to many fac44
tors, have apparently slowed the development of a comprehensive classification . Soil Taxonomy perhaps
comes closest to a basic system and
has received some degree of international recognition. Hierarchical
systems of this kind, however, risk
excessive proliferation of classes and
at the same time seem to lack accommodation for intergrade soils
(24). Other reviewers (25) have criticised the system on the basis of its
style of classification, narrowly defined classes, and attempts to reconcile the concept of polypedons
with the lack of discrete soil entities
in nature. Other problems concern
the classification of polygenetic soils,
especially those with pedogenic discontinuities occurring within 50 cm
of the surface . The classification of
profiles (pedons) containing buried
soils, multisequal soils, is troublesome because soil-stratigraphic sequences are more common than
generally believed (26). Some classifications make specific provision
for polygenetic soils (27). Only time
will tell whether this scheme or some
subsequent revision will become a
comprehensive world system.
In the meantime, geographers can
follow an eclectic approach applying
some system of their choosing to
the world scene or they can become
polydexterous using local systems
wherever their work takes them . Both
choices involve aspects of soil correlation and much expertise in the
field of soil classification . The problem is not one of merely changing
names on map legends because the
terms are frequently not equivalent
and hence map boundaries also must
be changed to reflect the new ter-
minology . Consideration of one
common soil group, the brown podzalic soils, illustrates some of the
difficulties involved . Brown podzolic
soils of the revised 1938 U.S. classification are approximately equivalent to Cryandepts, mesic families of
entic Fragiorthods and Haplorthods
and less so with Dytric Eutrochrepts,
Dystrochrepts, and Frgaiochrepts of
Soil Taxonomy. Approx imate correlations with other systems are Sol
ocre-podzolique (French system ,
1965), Leptic Podzol (FAD), Podzolic
Brown Earth (England and Wales),
and Brown Podzolic soil (Australia) .
Tables indicating relationships of
soils in Soil Taxonomy give a somewhat different approximate equivalent from the French taxonomy
(p. 440) to the current U.S.D.A. system , viz., Sols-ocre podzoliques are
indicated as being more or less
equivalent to frigid and mesic families of entic subgroups of Haplorthods, a rather more specific association than previously given (p. 433).
Thus, correlation of soil units requires detailed knowledge of soil
descriptions, class limits, and applicability of those definitions to extensions in widely separated natural
environments . Some surveys still
employ parts of the revised 1938
U.S.DA classification and it is generally not possible to equate those
great soil groups exactly with current great groups. In a few words,
taxonomic names are not interchangeable from one system to an other because concepts of soil are
modified as taxonomies evolve.
A partial solution to the problem
of multiple classification systems and
associated terminologies might in-
clude emphasizing aspects of soil
formation . A unified concept of
pedogenic regimes might help identify the main geographic zones or
physiographic regions dominated by
specific soil-forming processes. Areas
where certain processes are dominant would include, for example,
zones of podzolization, lateritization,
gleization, calcification, and salinization . Regions could then be stud ied in terms of pedogenic zonation
or in terms of soil-process interrelationships with other natural (rocks,
vegetation, climate) or cultural (settlement patterns, resource utilization) phenomena.
The global distribution of soils
has been depicted using many different classification schemes. Deployment of a comprehensive international soil taxonomy would do
much to alleviate existing con straints imposed by so many classifications. The diversity of soil taxonomies and the regions where they
are used suggests the possibility of
studying a "geography of soil classification." With few exceptions, soils
throughout the world are not so different that each requires a unique
classification . All soils should theoretically fit into a comprehensive
open-ended scheme. Is the proliferation of soil classifications that we
see today the result of scientific efforts to discover the best system, or
could it be partly the result of systems that reflect a certain degree of
national pride and cultural heritage?
CONCLUSION
The development of independent
soil classifications by national surveys has led to a classificatory di-
45
lemma . As the number of systems
increase, so does t he j argon and
tha t st ul ti f i es p rog ress when it
reaches overwhelm ing proportions.
When the re are approx i mat ely a
dozen major pedologica l class if ica t ions used to identify the same natural entity t here is ca use fo r concern
and , indeed , a desire for simpl ificat ion. The development of a un iversal , comprehensive soil classifica tion w i ll requ i re greate r un derstanding of soil systems and ,
perhaps more important ly , con certed international cooperation. Unti l
a comprom ise is reached and a
comprehens ive taxonomy is acceptable, geographers and othe r geoscientists must wade very carefully
through a variety of class ifications .
NOTES
1. In 1975 the Soil Conservation Service introduced Soil
Taxonomy, a new system of soi l classif ication (U.S.
Dept. Agric. Hndbk No. 436) rep lacing Baldwin, M., Kellogg , C. E., and Thorp, J., " Soil classification," in Ham·
ibidge, G. (ed.), Soils and Men, U.S. Dept. Agric. Yearbook 1938, pp. 979-1000; and revisions by Riecken, F.
F. and Sm ith, G. D., "Lower categories of soi l classif ication : Fam ily, series, type, and phase," Soil Science,
Vol. 67 (1949)' pp. 107-115, and by Thorp, J. and Smith,
G. D., " Higher categories of soil classification : Order,
suborder, and great groups," Soil Science, Vol. 67 (1949),
pp. 117-126. For a discussion of modern classification
schemes and the history of their development leading
to new and rev ised taxonomies. see Buol . S. W., Hole.
F. D" and McCracken, R. J., Soils Genesis and Classification (Ames: Iowa State Un iversity Press, 1980), pp.
194-224. In addition to the systems of national or cooperative soil surveys, there are other genera l classifications, e.g. FitzPatrick, E. A., Pedology (Edinburgh : Oliver
and Boyd, 1971 ), p. 306; as well as specialized systems
such as those dea ling with the organization of organic
soil materials, e.g. Ba l, L., M icromorphologica l Analysis
of Soils (Wageningen, The Netherlands : Soil Survey Institute ), p. 174; and pedograph ic studies involving micromorpholog ica l classification of inorganic materials,
e.g. Brewer, R., Fabric and Mineral Analysis of Soils
(New York : Wiley, 1964), p. 470 and Brewer, R., " Rela tionship between particle size, fabric and other factors
in some Austra lian soils," Ausr. Jour. Soil Science, Vol.
17 (1979), pp. 29-41 .
2. Examples of common interest include : Marbut, C. F"
" Soils of the Great Plains," Annals Assn. Amer. Geogr.,
Vol. 13 (1923), pp. 41-66; Shantz, H. L. and Marbut, C.
F.. "The vegetation and soi ls of Africs," Amer. Geogr.
Soc. Research Series No. 13 (1923, pp. 1-263; Walther,
J., " Das geo logische Alter und die Bildung des Laterits."
Petermanns Milt., Vol . 62 (1916), pp. 1-7 and 46-53 ; and
46
more recently Ganssen, R.. Bondengeographie (Stuttgart: Koehler, 1957), p. 219; Eyre, S. R., Vegetation and
Soils (Chicago : Aldine, 1963), p. 324; Bunting , B. T., The
Geography of Soil (Ch icago : Ald ine, 1965), p. 213. Two
recent attempts to incorporate the new terminology of
Soil Ta xonomy in geograph ical studies include textbooks by Steila, D., The Geography of Soils (Englewood
Cliffs, NJ : Prentice-Hall, 1976), p. 222 and Foth, H. D. and
Schafer, J. W., Soil Geography and Land Use (New
York : Wil ey, 1980), p. 484.
3. Soil Survey Staff, Soil Taxonom y: A Basic System of
Soil Classification for Making and Interpreting Soil Sur·
veys (Washington, D.C.: U.S. Government Printing Office , U.S.D.A. Handbook No. 436, 1975), p. 754.
4. Soil Survey Staff, Soil Classification, A Comprehensive
System, 7th Approxim ation (Wash ington , D.C.: U.S.
Government Printing Office, 1960) p. 503; Soil Survey
Staff, Supplement to Soil Classification System (Washington, D.C.: U.S. Government Printing Office, 1967), p.
207.
5. See for example the discussion in C. B. Hunt, Geology
of Soils (San Francisco : Freeman, 1972), pp. 18(}-183.
6. M . G. Cline, " Log ic of the new system of soil classification," Soil Science, Vol. 96 (1963), pp. 17- 22 ; C. E.
Kellogg, " Why a new system of soil classification," Soil
Science, Vol. 96 (1963), pp. 1- 5; S. W. Buol, F. D. Hole,
and R. J. McCracken, Soil Genesis and Classification
(Ames : Iowa State University Press, 1973), pp. 18(}-181.
7. C. W. Finkl, " Geographers, pedologists, and the new system of so il classification : A commentary for geographers," Prof. Geogr. , Vol. 19 (1967), pp. 239-243; D.
Steila, The Geography of Soils (Englewood Cliffs, NJ:
Prentice-Hall , 1976), p. 222.
8. FAO/ UNESCO Staff, Soil Map of the World, Vol. I, Legend (Paris: UNESCO, p. 59; National Soil Survey Committee of Canada, The System of Soil Classification for
Canada (Ottawa : Canada Department of Agricu lture,
1975), p. 255; J. S. Clayton, W. A . Ehrlich , D. B. Cann,
J. H. Day, and I. B. Marshall, Soils of Canada, Vol. I, Soil
Report (Ottawa : Canada Department of Agriculture, 1977),
p. 243; Martini, J. A .. " Principales grupos de suelos de
America Central y Mexico," Fititecnia Latinoamericanan,
Vol. 4 (1967), pp. 57-79.
9. J. Bennema, "Report to the government of Brazil on the
classification of Brazilian soils," FAD Report No. 2197,
p. 83.
10. B. W. Avery, " Soil classification in the Soil Survey of
England and Wales," Jour. Soil Science, Vol. 24 (1973),
pp. 324-338.
11 . E. MOckenhausen, F. Kohl, H. P. Blume, F. Heinrich, and
S. Miiler, Entstehung, Eigenschaflen und Systematik der
Boden der Bundesrepublik Deutschland (Frankfurt : DLGVerlag, 1977).
12. R. Tavernier and R. Marechal, " Soil survey and soil classification in Belgium ," 7th Internall. Congr. Soil Sci.
Trans., Joint Mtg. Comm. IV & V (1962), pp. 296-307.
13. G. Aubert, " La classification pedolog ique utilisee en
France," Pedolog ie, Spec. No. 3 (1965), pp. 25-51 ; P.
Duchaufour, Ecological Atlas of Soils of the World (New
York : Masson, 1978), p. 178.
14. N. N. Rozov and E. N. Ivanova, " Classification of the
soils of the USSR," Soviet Soil Science, Vol. 2 (1967),
pp. 147-156; E. N. Ivanova and N. N. Rozov, Classification and Determination of Soil Types (Wash ington, D.C.:
National Science Foundation, 1970), p. 271 .
15. S. P. Raychaudhuri and S. V. Govindarajan, "Soil genesis and soil classification," in Review of Soil Research
in India (New Delhi : Indian Council of Agricultural Re·
search, 1971), pp. 107-135; L. T. Hai, Soils of Taiwan
(Taipei : Society of Soil Scientists and Feni lizer Technolog ists of Taiwan, 1962).
16. K. H. Nonhcote, "A factual key for the recognition of
Australian soils," C.S.I.R.O. (Australia) Division of Soils,
Div. Repon 4160 (1960); C. G. Stephens, A Manual of
Ausrralian Soils (Melbourne : C.S.I.R .O., 1962). p. 48;
H.C.T. Stace et ai, A Handbook of Ausrralian Soils (Glenside, South Australia: Rellim, 1968', p. 435.
17. C. R. van der Merwe, Soil Groups and Subgroups of
Sourh Africa (Pretoria: Government Printer, 1962). p.
355; C. N. Macvicar, Soil Classificarion (Pretoria : Depanment of Agricultural Technical Services, 1977), p.
150.
18. N. H. Taylor, " Soil survey and classification in New Zealand," Proc. 7rh Pacific Sci. Congr.. Vol. 6 (1949), pp.
103-113; N. H. Taylor and I. J. Poh len, " The classifica tion of New Zealand soils," in Soils of New Zealand
(Lower Hun: New Zea land Depanment of Industrial Research, in press). The Soil Bureau is also considering
adopting Soil Taxonomy as the official system for the
national survey.
19. See for example Y. Kato, " Some discussions on the categories of Japanese soil classif ication," Pedologis r (To,
kyo), Vol. 21 (1977" pp. 2-18.
20. See summaries in Finkl , C. W. (ed.', Soil Classificarion
(Stroudsburg, PA : Hutchinson Ros s, in press', Benchmarks in Soil Science Series, Vol. 1. Examples of specialized soil classifications include : Arkley, R. J ., " Factor
analysis and numerical taxonomies of soils," Soil Sci·
ence Soc. Amer. Proc., Vol. 35 (1 971 ), pp. 312- 315; Asphalt Institute Staff, Soils Manua l fo r Design of Asphalr
Pavemenr Srrucrure (Houston : Asphalt Institute, 1969;
Barran, B. C., "A revised cl assification and nomenclatu re
21 . C. W. Finkl, "Soil," in R. W. Fairbridge and C. W. Finkl
(eds.). Encyclopedia of Soil Science, Pan I (Stroudsburg,
PA: Dowden, Hutchinson & Rossi Academic Press, 1979),
pp. 433-435.
22. J. C. F. Tedrow, " Systems of polar soil cl assification:'
in Soils of Polar Landscapes (New Brunswick, NJ : Rutgers University Press, 1977 ) pp. 114-135; E. C. J. Mohr
and van Baren, " Classification of tropical soils," in- Tropical Soils (The Hague: Uitgeverij W. van Hoeve, 1959).
pp. 472-489; Buringh, P., Imroducrion ro rhe Srudy of
Soils in Tropical and Subrropical Regions (Wageningen,
The Netherlands : Center fo r Agricultura l Publishing and
Documentation, 1979), p. 146; Oyama, M., " A classification system of paddy rice field soils based on their
diagnostic horizons," Bull. Nar/. Insr. Agric. Sciences,
Vol. 12 (1962), pp. 303-372.
23. For examples of effons toward development of comprehensive classification systems see : Crowson . R. A., etas·
sificarion in Biology (Chicago: Aldine, 1970). p. 350;
Hedberg, H.D. Inrernarional Srrarigraphic Gu ide (New
York: Wiley, 1976), p. 200; Mayr, E.. Principles of Sysremaric Zoology (New York: McGraw-Hili, 1969). p. 428 ;
Pettijohn , F. J. , " Classification of sandstones," Jour.
Geol.. Vol. 62 (1954), pp. 360-365; Simpson, G. G., Principles of Animal Taxonomy (New York : Columbia University Press, 1961 ). p. 247 ; Stoll, N. R. (ed.), Imernariona l Code of Zoolog ical Nomenclarure ( London :
International Trust for Zoological Nomenclature, 1964),
p. 176; Streckeisen, A. L., " Classificat ion and nomenclature of igneous rocks (final repon of an inquiry):' Neues
Jahrbuch f. M ineralogie, Abhandlungen, Vo l. 107 (1967 ),
pp. 144-214.
24. Butler, B. E.. So il Classificarion for Soil Survey (Oxford:
Clarendon, 1980), p. 129.
25. FitzPatrick, E. A .. Pedology, A Sysrema ric Approach ro
Soil Science (Edinburgh ; Oliver & Boyd , 1971 ), p. 306;
Jones, T. A., " So il classification-a destructive criti·
cism:' Jour. So il Science, Vol. 10 (1950), pp. 195-200;
Knox, E. G., " Soil individua ls and soil classification,"
Soil Sci. Soc. Amer. Proc., Vol. 29 (1 965), pp. 79-84.
of microscopic soil materi als with particular reference to
organ ic compounds," Geoderma, Vo l. 2 (1969) , pp.
257- 271 ; Brazilevich, N. I. and E. I. Pankova, " Classification of soils according to their chemistry and degree
of salinity," Agrokem Talajr, Vol. 18 (1 969), pp. 219-226 ;
Burm ister, D. M ., " Identif ication and classification of
soils," ASTM Spec. Tech. Publ. No. 113, pp. 3-24 ; Casagrande, A .. " Classification and identification of soils,
" Proc. Amer. Soc. Civil Engr., Vol. 76 (1947), pp. 783-810;
de Bakker, H. and J . Schelling, Sysreem van bodemclassificarie voor Nederland (Wageningen, The Netherlands :
Soil Survey Institute, 1966), p. 217 ; Forest Soils Division
Staff, " Classification of forest soils in Japan," Bull Govr.
Foresrry Exper. Sra. (Tokyo ), Vol. 280 (1975), pp. 21-28 ;
Hubrich, H.. " The cla ssification of soil types according
to hydrolog ical characteristics:' Arch iv. f. Acker-und
Pflanzenbau & Bodenkunde, Vol. 17 (1973). pp. 795-805.
26. Soil stratigraphy is a specialized field which deals w ith
the superposition of soil profiles. Soil-stratigraphic studies combine stratigraphic principles and practices with
pedolog ical techniques in attempts to resolve complexities of layered soil sequences. For funher information
see Morrison, R. B.. " Principles of Ouaternary soil stratigraphy," in Morrison, R. B. and Wright, H. E. (eds.),
Ouarernary Soils (Proc. VIIINOUA Congr.), Vol. 9 (1967),
pp. 1- 69 ; and Finkl, C. W .. " Stratigraphic principles and
practices as related to soil mantles:' CATENA. Vol. 7
(1 980), pp. 169-194.
27. For example, Duchaufour, P., Ecological ArIas of Soils of
rhe World (New York : Masson, 1978), p. 178; FitzPatrick,
E. A .. " Soil nomencl ature and classification," Geoderma,
Vol. 1 (1 967), pp. 91 - 105.
47