Agriculture Reference
In-Depth Information
and Portuguese (Botelho da Costa, 1954; 1959) literature. The Belgians introduced the term
Kaolisols
(Sys et al., 1961; Tavernier and Sys, 1965). Charter (1958), working in Ghana, used the
terms
. Though many descriptive terms were introduced to describe the
highly weathered soils of the tropics, most were not accompanied by quantitative deÝnitions. The
transitions of the Podsolics and the Latosols remained subjective and unresolved.
The term
Oxysols
and
Ochrasols
was created around 1954, during the development of Soil Taxonomy (Soil
Survey Staff, 1960; 1975), and the deÝnition was based largely on the Latosol concept. Thus the
class of Oxisols included many of the present-day Andisols, some Inceptisols, and some of the
AlÝsols and Ultisols. A more comprehensive deÝnition of the term Oxisols was published in 1960
by the USDA (Soil Survey Staff, 1960), and the concept, deÝnition, and classiÝcation were gradually
modiÝed and reÝned until the publication of Soil Taxonomy in 1975 (Soil Survey Staff, 1975). A
comprehensive review of Oxisols, including their use and management, is provided by Van
Wambeke (1992) and by Buol and Eswaran (2000).
Oxisol
A Consensus for Modern Classification
By the early 1970s, soil classiÝcation systems that had been initiated in the 1950s were maturing.
Soil Taxonomy was published in 1975 (Soil Survey Staff, 1975). But Dr. Guy D. Smith, the principal
contributor to Soil Taxonomy, felt that the knowledge and thus the classiÝcation of soils of the
tropics was incomplete, and indicated that these taxa and others in Soil Taxonomy should be
considerably modiÝed. FAO-UNESCO (1971Ï1976) began to publish the Soil Map of the World.
The legend of the soil map was developed and tested throughout the duration of the program, and
the Ýnal global soil map is good evidence that the legend served its purpose. The soil map of the
world, however, had areas where it was acknowledged that adequate information was not available,
and many such areas occur in the tropics. After publication of the global soil maps by FAO and
Soil Taxonomy by USDA-NRCS, an atmosphere of
descended on the richer countries,
and there was a visible decline in enthusiasm for reÝnements or other activities. Soil survey and
soil research in the tropics were also reduced, except in countries such as Brazil or in countries
that still maintained strong interest in the tropics, such as France and Belgium.
The cold war, ironically, turned out to be a boon for soil science in the tropics. The principal
global adversaries provided generous Ýnancial and technical support for Third World countries in
an attempt to garner political inÞuence. Some of the donor largesse trickled down to the technical
level and resulted,
fait accompli
, in increased soil resource inventory and pedological research. When
the relationships thawed during the decade of the last century, the richer countries lost interest in
the tropics and the tropical countries could not afford to support a similar research effort. In the
U.S., the international politics of the 1970s resulted in a major effort to improve Soil Taxonomy
for better application in the tropics. With funding from the U.S. Agency for International Devel-
opment, the Soil Management Support Services (SMSS) was created to enable the USDA Soil
Conservation Service (now the Natural Resources Conservation ServiceÏNRCS) to work in the
tropics (Eswaran et al., 1987).
Guy Smith, in collaboration with soil scientists from the U.S. and Europe, identiÝed many areas
in Soil Taxonomy that required priority attention. Several international committees (ICOMs) were
established by SMSS (Table 18.1) to rally soil scientists around the world to help improve Soil
Taxonomy. Simultaneously, there was an effort to develop a database of soils of the tropics to
backstop the ICOMs. In addition, the University of Puerto Rico, in collaboration with SMSS,
organized workshops (Beinroth, 1978a; 1978b; 1983; 1986) at which scientists could meet and
discuss the classiÝcation issues. Many of these activities are summarized by Eswaran et al. (1987).
The second edition of
inter alia
(Soil Survey Staff, 1999) has incorporated many of the
changes proposed by the ICOM as well as other changes submitted to NRCS from outside the U.S.
or suggested by soil scientists working in the U.S. Because of the investments involved and the
time available, not all soils in the tropics could be scrutinized in the manner done by the ICOMs
Soil Taxonomy
