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a Hey and Associates, 53 W. Jackson Blvd., Suite 1015, Chicago, IL 60604
b Dep. of Natural Resources and Environmental Sciences, Univ. of Illinois at Urbana-Champaign, 1102 S. Goodwin Ave., Urbana, IL 61801
c Illinois St. Geol. Surv., 615 Peabody Dr., Champaign, IL 61820
d Dep. of Geography, Univ. of Illinois at Urbana-Champaign, 607 S. Mathews Ave., Urbana, IL 61801
* Corresponding author (chicago{at}heyassoc.com)
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Abbreviations: ASSA, American Soil Survey Association • FAO, Food and Agriculture Organization
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Both disciplines developed from pioneer geologist Abraham G. Werner's geognosic concern with the surface of the earth of the late 18th and early 19th centuries (Tandarich and Sprecher, 1994; Tandarich, 1998). The agricultural purview of the developing science of geology became known as Agrikulturgeognosie, or agricultural geology (Tandarich and Sprecher, 1994; Tandarich, 1998). When agricultural geologist Friedrich A. Fallou (1862) defined soil science that he called Naturwissenschaft Bodenkunde or Pedologie, as distinct from Sprengel's (1837) Bodenkunde (soil knowledge), he stressed the need to study soil under "one main concept" (Tandarich and Sprecher, 1994; p. 7). We suggest that the concept for soil study, formulated as a response to Fallou, was the soil profile.
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Evolution of The Soil or Pedological Profile |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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The Diverse European Origins of the A-B-C Soil Profile |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Danish scientist Pieter E. Müller, who stated that he was influenced by Orth's work, used the letters a, b, and c in soil profile diagrams (see cover) and analyses (Müller, 1878). His (Müller, 1878) designations were: a = torf (turf), b = bleisand (bleached sand), b' = rotherde (reddish earth), and c = untergrunde (underground). However, the paper was not published until 9 yr later (Müller, 1887). In the meantime, Dokuchaev had published his concepts (Dokuchaev, 1879a, 1879b, 1883) and it is, therefore, Dokuchaev's name that has become associated with the soil profile and not Orth's or Müller's.
Most soil scientists probably don't associate Charles Darwin with soils, but he made soil-biota process observations intermittently for over 40 yr, which culminated in his "worm" book (Darwin, 1881). Russian pedologist A.A. Yarilov (1936) even honored Darwin as "the founder of soil science", adding that Rothamsted Research Station manager Edward J. Russell endorsed the book as "the most interesting book ever written about soil" (see also Johnson, 1999). A diagram in the book shows a soil profile with an A-B-C-D sequence of horizons or layers, with the A indicating sod, the B the main vegetable mould (topsoil), a C horizon representing a stone-line, and a D apparently representing bedrock (chalk).
Dokuchaev (1879a)(1879b) credited Fallou and Orth as having influenced his own thinking. We suggest that, following on Fallou's and Orth's work, Dokuchaev (1879a)(1879b, 1883) crystallized the "one main" concept of the soil as an independent natural body, seen in a profile composed of horizons that facilitated soil to be systematically described, compared, and classified.
Dokuchaev (1879a)(p. 25–28), in his initial lectures of 1877 through 1878 on the Russian Chernozem published in French, formulated a concept of soil siège (appearance) as a construction (arrangement) of "trois énchantillons (layers): le premier de la couche [layer or stratum] du sol [A, le second [B]– de la couche transitionaire, et le trosième [C]– de la roche primitive [original rock]." Dokuchaev (1879a)(p. 27) appears to use énchantillons and couches interchangeably.
In his first major work on soil published in Russian, Dokuchaev (1879b)(p. 70–71) used two phrases when he spoke of what is now known as the profile: "
In the first Russian soil work published in English, Dokuchaev and Nikolai M. Sibirtsev (1893) introduced the A-B-C scheme into the USA at the 1893 World's Columbian Exposition in Chicago, IL (Tandarich et al., 1988; Simonson, 1989). Dokuchaev and Sibirtsev (1893)(p. 4) described the concept of the soil cut, in which "always and everywhere there could be distinguished by the three following levels: A.–level of the soil; B.–transitive level of the soil; C.–primitive-rock (subsoil)." The thickness of the soil was represented by "A + B" (Dokuchaev and Sibirtsev, 1893, p. 7). However, neither the terms profile nor horizon was used in this publication.
Dokuchaev (1900)(p. 35) presented a "système des zones verticales de sols ..." at the Universal Exposition of 1900 in Paris (Exposition Universelle de 1900 à Paris). He used the term l'horizon equivalently with zone vertical in his publication (Dokuchaev, 1900). The A-B-C "profil de la coupe [scheme] des zones verticales des sols ..." also included a D horizon when necessary (Dokuchaev, 1900, p. 40). The D horizon was not defined—only described as being below a C horizon.
In Russia, Dokuchaev's profile–horizon concept evolved through application by his students, such as Sibirtsev (1900), S.A. Zakharov (1906), and Konstantin Glinka (1908)(1914, 1915). The Glinka (1914) profile became known in Germany through Glinka's collaboration with Orth's student Hermann Stremme (Tandarich and Sprecher, 1994), and consisted of an eluvial A, an illuvial B, and the parent rock or C horizon. Although the A-B-C profile was known in Europe through Müller's (1887) work, it appears to have been used only in Russia (e.g., Sibirtsev, 1900; Zakharov, 1906; Glinka, 1908, 1915), and Germany (Ramann, 1911; Glinka, 1914) until about 1920.
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The Soil Profile Concept in the United States of America |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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George Coffey (1912)(p. 8) considered the soil "an independent, natural body, a bio-geological formation," consisting of a "surface soil" and a "subsoil." The author of the U.S. Bureau of Soils (1914) Instructions to Field Parties (who Simonson [1987] believes was Curtis F. Marbut, Coffey's successor as head of the U.S. soil survey program) defined the soil section, composed of soil material, as including the topsoil, subsoil, and substratum layers.
Marbut (1927) discovered the soil profile while translating Glinka's (1914) work during a 3-yr period (1914–1917). Marbut wrote in his personal papers that advancement of the Russian work was a politically sensitive issue because of the anti-Russian sentiment in the U.S. Bureau of Soils. He stated, "I had to work in secret. I was called a Russian worshipper by my own men. Whitney had a reputation for getting rid of those who did not agree with him [e.g., Coffey]. I told him [Whitney] that I would follow his orders, but would think for myself" (Lankford et al., 1985, p. 39, Folders 141–144). Marbut had completed and prepared a limited number of carbon copies of the Glinka translation for circulation to a few selected persons by 1920 (Lankford et al., 1985, vol. 5, p. 40). However, it appears that he waited to have the translation published until the U.S. Bureau of Soils head Whitney was too ill to oppose it. The translation was finally "published" (albeit in mimeograph form) in conjunction with the First International Congress of Soil Science in 1927 (Marbut, 1927).
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United States' Soil Profile Evolution in the 1920s and 1930s |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Simonson (1987)(p. 13) has declared, without documentary evidence, that the ASSA was formed "to counteract the growing influence of C.F. Marbut." Perhaps such resistance by some ASSA members to either Marbut or the use of the profile concept led to a statement by P.E. Brown of Iowa State University made at the 1923 ASSA meeting:
What has been the accomplishment to date in soil survey research? Little beyond the accumulation of knowledge of soil characteristics and a change of viewpoint. Both are most significant. Dr. Marbut in his discussion on soil classification at the Michigan meeting of the Association (Marbut, 1922) emphasized the fact that a beginning has just been made in soil science, by the gathering of facts. He also called attention to the changed views on the subject. It took a long time to bring about a conviction that soil mapping was not a geological operation and there are still some men in the field who see soils geologically rather than from a true soils viewpoint.The suggestions which Dr. Marbut made were timely and should lead to a different conception of soil survey in relation to soil science. The study of soil profiles, the sorting of the various factors serving to differentiate soils on the basis of profile characteristics and the gradual accumulation of a fund of soil information, from the soil and not the geological, agricultural, or botanical standpoint will certainly lead to a rapid development of soil science.
It is not necessary to agree to all Dr. Marbut's premises, to accept his grouping system or to follow his ideas absolutely but he certainly offers suggestions which merit our careful consideration.
(Brown, 1924, p. 22)
Brown clearly represented a faction of ASSA members willing to evaluate and accept new ideas regardless of origin. His statement reflects an emphasis on the use of the profile as a concept for studying soils as independent entities, paving the way for the development in the USA of what is now known as pedology.
Bridges (1997)(p. 52) relates a personal communication from Simonson who stated that during 1924 "a circular was issued which contained instruction on the use of the A-B-C designations; its anonymous author was Marbut." This explains how a symposium "Profile Studies of Four Major Soil Groups" could be organized at the 1924 ASSA meeting in Chicago. The presented papers, published later, used the A-B-C designations in a generally consistent way: J.C. Russell and E.G. Engle (1925) on the central prairies, H.H. Krusekopf (1925) on brown soils of the north central states, Earl Fowler (1925) on coastal plain soils, and Veatch (1925) on northern podsol soils. Charles F. Shaw (1925)(see cover) also used the A-B-C designation in his report on Australian soils. Veatch (1925)(p. 27) refers to the A-B-C profile as "the Glinka scheme." This was 2 yr before the mimeographed Marbut (1927) translation of Glinka was available in the USA; carbon copies of the translation were circulating within the professional community.
A symposium on "Soil Profile Studies" was held at the 1925 ASSA meeting. All of the presentations and subsequent publications featured the A-B-C system: Thomas D. Rice (1926) on prairie soils, Mark Baldwin (1926) on northern timbered soils, William Hearn (1926) on southern soils, and Macy H. Lapham (1926) on western soils.
In 1926 Shaw, who was serving as chairman of the ASSA Committee on Terminology, proposed a terminology glossary (Shaw, 1927). Here, for the first time, definitions were compiled, including soil layer, soil horizon, and soil profile. The term soil layer was used in descriptions of the soil section since the inception of soils surveys in the U.S. Bureau of Soils in the late 1890s (U.S. Bureau of Soils, 1914; Simonson, 1987). The terms horizon and profile were more recent arrivals through Glinka (1914) and Marbut (1927). Shaw merely equated the definitions of soil horizon and soil layer; the correspondences between them are summarized in Table 1.
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Shaw presented the glossary at the First International Congress of Soil Science in 1927 (Shaw, 1928a), and again later that year at the 1927 ASSA meeting where it was formally adopted by the society (Shaw, 1928b). The Shaw (1929) profile shows an appreciation for characterizing the region beneath the A and B horizons: C1 represents oxidized, leached, C2 is oxidized, unleached, and CN equals unaltered parent material (the CN designation, rewritten as Cn, was used 45 yr later by Birkeland (1974) for unaltered parent material).
After the horizon definitions were adopted by the ASSA in 1928, no real consensus was reached in the profession regarding horizon definitions. The ASSA appointed a Committee on Horizon Criteria, chaired by E.A. Norton, to develop standard horizon definitions. C.C. Nikiforoff (1931) cursorily reviewed the history of the A, B, and C horizons, possibly as background for the committee. The committee met from 1931 to 1934 and the results were reported by Norton (1932)(1933, 1934, 1935), but no consensus on standard definitions was reached. In its final statement, the committee decided to leave horizon concepts flexible and their definitions deliberately imprecise to allow application over a wide variety of conditions (Norton, 1935).
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National and International Profile Formalization |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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This dogmatic C horizon became part of the theoretical base of pedology through Roy W. Simonson's work. He (Simonson, 1959, p. 152) proposed that it had an "indefinite lower boundary." According to Simonson and David R. Gardner (1960, p. 128), the pedon concept "would ... [extend] downward far enough to include the full set of genetic horizons. The lower boundary [of the C horizon] cannot be defined clearly, nor can it be established conclusively in many instances by direct observation. It must remain somewhat vague, as does the lower boundary of the soil itself."
On an international level, the Food and Agricultural Organization (FAO) (1977, p. 18) stated in its horizon designation guidelines that the "C ... should not be labeled as [a] ‘soil horizon’ but as [a] ‘layer,’ since [its] characteristics are not produced by soil forming factors." However, the FAO also declared that the C horizon "does not show properties of any other master horizons" (FAO, 1977, p. 20).
We have listed subsolum horizons and their definitions in Table 2. In most instances the designations were assigned to intervals between the solum and unweathered material or bedrock.
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A-B-C Profile Expansion And Alternatives |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Eugene P. Whiteside (1959) proposed a series of morphogenetic horizon designations in place of the A, B, and C. His profile below the solum consisted of pedogenetic horizons W (water leached, oxidized, and slightly altered) and X (unknown). These pedogenetic horizons were distinguished from petrogenetic horizons P (primary material—unaltered, unleached, and unoxidized layer) or U (underlying, unrelated materials). In addition, Whiteside (1959) advanced a total profile concept, the soil, which extended from the surface (V) to the unaltered (P). While Whiteside's proposals were not wholly adopted, his E horizon designation was used in the FAO (1973, 1977) and later Soil Survey Staff (1981)( 1993) systems.
E.A. Fitzpatrick (1967)(1980, 1988) also broke with tradition and formulated an alternative approach to the A-B-C-horizon designation. His system categorized all major horizons into 77 types based on their own characteristics and diagnostic properties. Such a large system adds precision and important distinction, but is difficult to remember and apply in the field.
The study and classification systems of soils around the world were largely developed independently from one region to another. The systems were largely built on regional experiences. Nevertheless, in recent decades the A-B-C concept of soil profile has been used to denote the master horizons of most soils of the world. The A-B-C notation is most easily applied in youthful landscapes, particularly in those regions glaciated during the Pleistocene. Its application in areas outside of glaciated regions has been more problematic.
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A-B-C Use in Deeply Weathered Profiles |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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o
, meaning rotten] for thoroughly decomposed, earthy, but untransported rock. When the exact character of the original rock is known it is easy to qualify this term and to speak of ‘granitic saprolite,’ and the like" (Becker, 1895, p. 289–290). Although Becker (1895)(p. 290) observed soils above the saprolite, he neither described the soil and saprolite nor attempted to genetically relate them in a profile. Fowler (1925) was the first to apply the A-B-C profile to deeply weathered soils of the Piedmont and Coastal Plain. He subdivided the C horizon into two members: the C1 was parent material weathered from bedrock that retained its geological character and could extend downward many feet, and the C2 was the unaltered parent material bedrock (Fowler, 1925). Marbut (1928), in his USDA Graduate School lectures, recognized that the C horizon of certain soils in the Piedmont often extended down several tens of feet (several meters) into the disintegrated and decomposed (his terms) rock. He discussed analyses of C horizon samples at 25 (7.6 m) and 75 foot (22.7 m) depths (Marbut, 1928). Shaw (1929) included disintegrated bedrock in his C horizon definition. William Battle Cobb (1931)(p. 87) in his study of chemical constituents lost from horizons in selected Georgia soil profiles, distinguished between the C horizon and the "less weathered lower horizons" that he called "weathered rock." R.C. Jurney (1935)(p. 57) recognized that "lying between the bedrock and the soil [A+B horizons] itself is a deep zone of material which cannot be classed either as rock or as soil." He called this zone the C horizon and defined it as "the place of decomposed rock material which is gradually changing into soil" (Jurney, 1935, p. 57). O.C. Bryan (1935)(p. 66–67) used the designation C for disintegrated and decomposed rock in the soil profile.
In the tropics, as one of us pointed out (Johnson, 1994), an alternative profile scheme was formulated by some workers in the 1950s through 1960s. In his cocoa soils studies, C.F. Charter (1949) observed that humid tropical soils in South America and Africa typically exhibit three-layered profiles: a fine fraction mantle (topsoil, surface mantle), above a stony layer (stone-line), over weathered regolith or weathered bedrock. P.H. Nye (1954), working in Nigeria, subsequently gave two master horizon designations for such three-layered soils: a surficial Creep (Cr) Horizon that includes the surface mantle and the stone-line), and a Sedentary (S) Horizon for the subjacent weathered zone. J.P. Watson (1961), working in southern Africa, renamed the three horizons as follows: M for mineral mantle, S for stony layer (stone-line), and W for the weathered zone, a much simpler and more straightforward scheme. Donald L. Johnson (1994), in comparing humid tropical soils with humid midlatitude soils, averred that the midlatitude A-E-B-C scheme is basically the same as the M-S-W scheme, where A = M, E = S, and B + C = W, and that the same basic genetic processes produce them (many midlatitude soils have stone-lines at either the AB horizon interface, or the EB horizon interface).
The deeply weathered profiles developed in bedrock began to receive more attention from pedologists since the 1950s (Stolt and Baker, 1994). The term saprolite, as originally defined by Becker (1895), began to be used in U.S. soil surveys in the 1960s. Larry T. West (personal communication, 2000) stated that the earliest use of the term that he had seen was the Clarke and Oconee Counties, Georgia soil survey correlated in 1965 and published in 1968 (Robertson, 1968); and that the term appears to have entered the published soil science literature (at least in the USA) by 1973 (Ojanuga, 1973).
H.H. Eswaran and W.C. Bin (1978) recognized distinct zones within the weathered bedrock portion of profiles and modified the concept of G. Stoops (1967) to address the situation. Their zones are briefly described as: 
= A + B, ß = accumulated gravel either with (ß1) or without (ß2) petroplinthite, 
m = mottled zone with plinthite, p = pallid zone, = evident rock structure, and R = cohesive rock (Eswaran and Bin, 1978).
Stanley W. Buol, his colleagues and students, have studied profiles in deeply weathered rock worldwide for over 25 yr. C.S. Calvert et al. (1980) applied the designation R-S to the saprolite and the R-U to the unweathered bedrock portion of these profiles. Within a short time, E.L. O'Brien and Buol (1984) used C for saprolite. After further consideration, T.J. Rice, Jr. et al. (1985), R.A. Rebertus and Buol (1985), and Griffin and Buol (1988) applied Cr to the saprolite portion of the profile. The designation Cr was originally used in the FAO (1973, 1974, 1977) system for strong reduction from groundwater influence. However, the Soil Survey Staff (1981)(1993) chose to designate weathered or soft bedrock by Cr.
However, Buol found imprecision in the concept of saprolite, its use and application and has developed a provisional taxonomic classification for it (Buol, 1994). Most recently, P.J. Schoenberger et al. (1995), Li et al. (1997), and Buol et al. (2000) have used the C for saprolite.
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The Solum: A European Scientific Soil Concept |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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In 1926, Shaw (1927) defined the solum as the weathered part of the soil profile, and had restricted the term to the A and B horizons. Marbut (1928)(1951) called the solum the "true soil," the "mature soil," or the "soil layer." However, outside of the USA, some scientists, such as D. Baize (1993) in France, appear to retain Frosterus' original concept of the solum as the weathered portion of the earth's crust; his conceptual solum and reference profiles include the A, B, and C horizons.
The original solum concept embodied the entire soil profile, not just the A + B. However, the solum concept in the USA has been restricted to the A and B horizons for the last 70 yr and this notion has spread globally. Nevertheless, a concept of a total solum incorporating the entire A-B-C profile has utility and is suggested in the profile concept of Norton and Smith (1928), the soel concept of Whiteside (1959), and the pedoweathering profile of John P. Tandarich et al. (1994).
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Development of Homologous Profile Concepts |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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In the 20th century study of Pleistocene geology, the concepts of the geologic weathering profile (Tandarich et al., 1988), and soil stratigraphy (Morrison, 1967, 1978) evolved to form a geological basis for understanding soils. Initially this evolution took place in schools and governmental agencies within the mid-continental USA where glaciated landscapes were prevalent. These institutions included the Universities of Chicago, Illinois, and Iowa, and the geological surveys of midwestern states.
Colleagues of Shaler and Hilgard, Chamberlin, and Rollin Salisbury at the University of Chicago, trained George F. Kay (see cover). Kay was the originator of the term gumbotil (Kay, 1916) and geologic weathering profile (Kay and Pearce, 1920) concepts. Kay (1916)(p. 637) characterized gumbo(til) as "a grayish, tenacious, thoroughly leached, and nonlaminated joint clay." According to Kay (1916)(p. 637), "gumbotil is chiefly the result of weathering of till," but he never referred to it as soil. He gave a paper before the ASSA in 1929 (a reworking of portions of Kay and Apfel, 1928) entitled Gumbotil, its characteristics, origin and significance (Kay, 1930). Kay described stages of the alteration processes of the gumbotil and weathering profile:
solution, hydrolysis, the formation of colloids and crystalloids, precipitation and leaching, the gradual passage downward of all the transportable elements of the till, including the iron, the silica, the colloidal clays, and similar colloidal silicates. The resultant residuum of the chemical leaching process is a practically insoluble stratum—the gumbotil. In addition, such physical factors as wind action, freezing and thawing, and burrowing of ground animals may have played some part (Kay and Apfel, 1928, p. 111–112; Kay, 1930, p. 134–135).
However, Kay stopped short of declaring the processes listed above to be soil-forming processes and the weathering profile, including the gumbotil, to be coequal to a soil profile. Yet he (Kay and Graham, 1942) equates the gumbotil and weathering profile zones as defined by Morris M. Leighton and Paul MacClintock (1930; see below) to "soil profile horizons." Kay's weathering profile zones are unnumbered or otherwise symbolically designated: gumbotil, oxidized and leached till, oxidized and unleached till, and unoxidized and unleached till (Kay and Apfel, 1928; Kay and Graham, 1942).
We suspect that Kay was influenced by the work of Stevenson and J.F. Barker (1911) at Iowa State University on "gumbo soils" of Iowa. As Kay's archival papers on the weathering profile are missing and presumed lost, we may never know if he corresponded with soil scientists as he formulated his ideas. Kay collected publications on soils, particularly soil survey reports, and corresponded with soil scientists Bushnell, Conrey, Norton, Rice and Smith in the 1920s and 1930s (Kay, n.d.).
A student and colleague of Kay, Leighton (see cover), refined the weathering profile concept. Leighton (1958) relates that, during his early years at the University of Illinois, he was inspired both by Glinka's work (1914) and Marbut's. Between January and July of 1923, Marbut gave a series of lectures at the University of Illinois that Leighton attended, and field trips were organized by university faculty members (Smith and others) to allow Marbut to view Illinois soils and comment on their characteristics and classification. The note cards of the soil profiles Marbut saw on this field trip are in the Marbut Collection (Lankford et al., 1985).
As a result of this experience Leighton (1958)(1959; Leighton and MacClintock, 1930, 1962) credited Marbut for insights obtained on the soil profile and its application to studies of Pleistocene weathering profiles. In addition, Leighton had good rapport with the soils faculty at the University of Illinois during the 1920's. He particularly credited Smith and Norton, who were working on their own profile concepts at the time (see above and Table 2), for their "active collaboration" who "directed attention especially, and with great helpfulness, to the detailed characteristics of the soil and immediate subsoil materials" (Leighton and MacClintock, 1930, p. 30).
Leighton (1958)(p. 704) explained that the weathering profile "was used as the geologic homologue of the pedologic term soil profile and also in recognition of the differences in the objectives, scope, and application of geology and pedology." Leighton (1958)(p. 705) emphasized that "it should be clear that the geologic terms weathered zone and profile of weathering and the pedological terms soil and soil profile refer to the same thing." Unfortunately, many users have consequently assumed that the actual profiles are different because the words are different. This partitioning of geological and pedological contexts was decided in an unwritten agreement resulting from a meeting between Leighton and Marbut during the latter's 1923 lectures and field trips in Illinois (Leighton, 1958). As a result, the soil and geologic profile concepts were treated independently and, in many cases, differently or even mutually exclusive from each other. Hence, later concepts evolved beyond original intentions.
Quaternary geologists in the 1920s were interested in soil profiles, but considered them less important than other geological endeavors. Agricultural geologists at the time were trying to diminish or rid themselves of their dependence on geological theories and create an independent soil science, with a subdiscipline concerned with soil genesis known as pedology. The Leighton–Marbut agreement was seemingly a matter of convenience to delineate professional domains. This led to views that soil is not part of geology and vice versa.
The Leighton and MacClintock (1930)(1962) weathering profile is similar to the Kay and J.N. Pearce (1920) profile except that the weathering zones were numbered from 1 through 5. Horizon 1 was restricted to the part called the surficial soil, the A horizon. The gumbotil proper, later correlated with the B(g) horizon by Simonson (1941) was designated Horizon 2. Horizons 3 through 5 were within the C horizon: Horizon 3 was oxidized and leached; Horizon 4 oxidized and unleached; and Horizon 5 unoxidized and unleached (unweathered). The Leighton and MacClintock weathering profile was used in Illinois and elsewhere in Pleistocene geologic studies until a revision was made by John C. Frye, H.B. Willman, and Herbert D. Glass. This revision began to evolve in the late 1940s and the 1950s.
Frye, a Pleistocene geologist at the Kansas Geological Survey between 1942 and 1954, became acquainted with pedologist James Thorp, the U.S. Bureau of Chemistry and Soils, Division of Soil Survey regional correlator for the Great Plains. Glass (personal communication) stated that Frye became sensitive to the soil science literature and soil studies relative to Pleistocene stratigraphy through communication with Thorp and his published works (e.g., Thorp, 1949; Thorp et al., 1951).
Frye came to the Illinois Geological Survey and succeeded Leighton as Chief in 1954, holding the post until 1974. Willman, a stratigrapher, had been working at the Illinois Survey since 1926, and Glass, a clay mineralogist, since 1948. The three began collaborating on Pleistocene soil studies in 1958 (Glass, personal communication, 1987) and produced major works on the concepts of gumbotil, accretion-gley, and the geologic weathering profile concept (Frye et al., 1960; Willman et al., 1963, 1966).
Close linkage with the pedological profile is an integral part of the Frye, Willman, and Glass profile though they were uncomfortable with the term horizon, preferring instead zone. Their A-zone and B-zone are equivalent to the A and B horizons of the 1951 Soil Survey Manual (Soil Survey Staff, 1951). The subdivisions of the C-zone (pedological C horizon) were threefold: CL, leached and oxidized; CC, unleached and oxidized; and UU unoxidized and unleached.
The Kay–Leighton–Frye weathering profiles were all developed to describe pedogenic horizons that they observed below the solum in youthful glacial deposits. Outside glaciated regions of the world, some geologists (and pedologists) have been using the term weathering profile to encompass both the pedological profile (solum), and the subsolum extending down to the unweathered bedrock (Pavich, 1986, 1989a, 1989b).
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Interdisciplinary Communication And Concepts |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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Peter W. Birkeland, a Quaternary geologist influenced by pedologist Hans Jenny when at the University of California, Berkeley, has published on the interrelationships of pedology, Quaternary geology, and geomorphology (Birkeland, 1974, 1984, 1999). Birkeland modified the soil horizon designation system of the Soil Survey Staff (1951) by adding a Cox for an oxidized C horizon, and a Cn for unoxidized C (Birkeland, 1974). The latter was changed to "Cu" in 1981 in response to the horizon designation changes of the Soil Survey Staff that year (Birkeland, 1984).
In 1978, Quaternary geologist George R. Hallberg of the Iowa Geological Survey, and Iowa State University pedologists Thomas E. Fenton and George R. Miller developed a hybrid profile descriptive system that incorporated notations from both the pedological and geological profiles. Letter clusters represent observed conditions below the pedological solum in loess and till: e.g., OL = oxidized, leached; OU = oxidized, unleached; and UU = unoxidized, unleached (Hallberg et al., 1978).
Independent of the Iowa effort, pedologist and Quaternary geologist Leon R. Follmer of the Illinois Geological Survey, influenced more by Leighton's profile ideas than Frye's, developed a fourfold division of the C horizon (Follmer, 1979, 1984) that subdivided the region below the solum and included the unweathered portion of the profile (Table 2). More recently, Follmer et al. (1985) and Tandarich et al. (1994) introduced the pedoweathering profile concept, which contained pedogenic C and geogenic D horizons (Table 2), and integrated the functional parts of the pedological and geological profiles.
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Discussions and Implications |
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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In the USA, the soil profile as originally defined by Shaw, ranged from the surface to its unweathered base. However, the practical agricultural concerns of the Soil Survey Staff replaced the more flexible ideas of the ASSA regarding horizon definitions. The shallow profile model of the USDA has traditionally emphasized the solum: the A and B horizons of agricultural concerns, the focus of soil survey interest. For these reasons, the subsolum C horizon has traditionally been deemphasized and largely disregarded. Simonson viewed the C in his profile concept as vague, with an "ill-defined" upper and lower boundary; the FAO considered the C to be unaffected by soil-forming (pedogenic) processes.
The deep profile stratigraphic concerns of geologists and geomorphologists led to an expanded profile developed from, and essentially a homologue of, the pedological profile. In spite of efforts by Thorp, Ruhe and others to integrate them, these two approaches artificially created by Marbut and Leighton, the pedological and geological, were seen as unrelated by some practitioners. The subsolum emphasis of the weathering profile not only applied to Quaternary deposits, but also extended to deeply weathered bedrock (Pavich, 1986, 1989a, 1989b; Cremeens et al., 1994).
Recently, pedologists, Quaternary geologists, and soil geomorphologists have suggested and used profile concepts that are synthetic, i.e., they incorporate concepts and ideas from pedology and geology—what the German scientists of the late 19th century called geopedology (Yarilov, 1927). When pedologists expand their study of the soil profile to greater depth, they will find geopedological profile definitions and applications useful. A geopedologic model can aid communication, promote understanding of the whole profile to a higher level than the five-factor model of Jenny (1941) or current models can do, and will provide more reliable interpretations of soil genesis and soil use. Also, as a consequence of a deeper view, it will attract other disciplines that, in reality, have overlapping interests with pedology.
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ACKNOWLEDGMENTS |
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Received for publication June 5, 2000.
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TOPABSTRACTINTRODUCTIONEvolution of The Soil...The Diverse European Origins...The Soil Profile Concept...United States' Soil Profile...National and International...A-B-C Profile Expansion And...A-B-C Use in Deeply...The Solum: A European...Development of Homologous...Interdisciplinary Communication...Discussions and ImplicationsREFERENCES |
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