Agriculture Reference
In-Depth Information
soil formation under ambient conditions. If this approach is used, an Anthrosol order should be
placed at the beginning of the key to allow use of these restricted criteria for Ýrst identifying a soil
as a member of this order. This approach is used in the Australian Soil Taxonomy, in which
knowledge of process is allowed in classifying anthropogenic soils, but subsequent orders are
deÝned using morphology-based criteria. Their experience should be evaluated prior to adopting
this approach. It seems probable that the most common debatable classiÝcation would arise from
the inclusion of a soil that some might argue has not been sufÝciently modiÝed by anthropogenic
processes to warrant inclusion in Anthrosols. Restricting modiÝed rules for deÝning criteria to a
single Anthrosols order is not a perfect solution. DifÝculties in deÝning extragrades within other
orders would continue to be a problem. For example, most taxonomists would probably prefer that
a moderately eroded Mollisol be classiÝed as an anthropogenic extragrade of Mollisols, rather than
an Anthrosol. Nevertheless, a separate soil order of Anthrosols that allows special rules for iden-
tifying anthropogenic soils and the broad spectrum of anthropogenic properties seems to be the
best option for incorporating anthropogenic processes in Soil Taxonomy, with minimal disturbance
to the rest of the system.
CONCLUSIONS
To those taxonomists who are purists with respect to the original fundamental principles of Soil
Taxonomy, the proposed approaches to incorporating anthropogenic processes in soil classiÝcation
systems such as Soil Taxonomy that utilize morphology-based criteria are sure to be unacceptable.
It could also be argued that adopting different rules of classiÝcation within a single soil order in
Soil Taxonomy is little more than publishing two separate classiÝcation systems within the same
topic. However, it is our opinion that incorporating all anthropogenic soil processes in Soil Tax-
onomy under the present set of principles of classiÝcation is not possible, because some anthro-
pogenic soil processes do not leave morphological evidence. The evidence of anthropogenic activity
is often expressed in the lack of horizonation, altered chemistry, or difference in landform relative
to surrounding parent soils.
Soil Taxonomy was designed in part for the purpose of classifying, in an objective manner,
soils that formed by natural processes of soil formation. It provides a framework for assessing our
knowledge of soil formation. By exempting all or part of the system from the principles that provide
for the objective classiÝcation of soils without the use of knowledge of process of their formation,
the system may be weakened with respect to this purpose of classiÝcation. However, the injury
may be minimized if the new rules are restricted for use within a single soil order that falls out
Ýrst in the key to soil orders. Taxonomists should decide just how important this aspect of the
system is for future applications. In our opinion, weakening this aspect of Soil Taxonomy in one
soil order is a reasonable alternative to restructuring classes throughout Soil Taxonomy, and to
being unable to incorporate anthropogenic soils into our classiÝcation (and mapping) system at all.
REFERENCES
Ahrens, R.J. and Engel, R.J. 1999. Soil Taxonomy and anthropogenic soils, in J.M. Kimble, R.J. Ahrens, and
R.B. Bryant, Eds. ClassiÝcation, Correlation, and Management of Anthropogenic Soils. Proceed-
ingsÐNevada and California, Sept. 21-Oct. 2, 1998. USDA-NRCS, Nat. Soil Survey Center, Lincoln,
NE.
Burghardt, W. 1994. Soils in urban and industrial environments.
157:205Ï214.
Chinese Soil Taxonomy Research Group. 1995. Chinese Soil Taxonomy (Revised Proposal). Chinese Agri
Sci. Tech. Press, Beijing, China (in Chinese).
Craul, P.J. 1999.
Z. PÞanzenern Bodenkunde
Urban Soils: Applications and Practices
. John Wiley & Sons, New York.
