Soil and the Environment - Soils for Fine Wines - page 6

Box 1.3 Soil Classification

Soil scientists have long sought to create order out of apparent chaos. The
traditional approach to classification in biology is to allocate “like individuals” to
the same class, whereas “unlike individuals” are assigned to other classes. Names
and a summary of the key distinguishing properties of each class identify the
classes. This is called classification .
With plants and animals, the genetic inheritance of traits in individuals is
strong and forms the basis of the Linnaean system of classification. The genetic
influence in soil formation is weaker and is often obscured by environmental
factors and human interference. So soil scientists have devised other ways of
classifying soils that take into account, to varying degrees, genesis of the soil, the
influence of environmental factors, and actual soil properties. Many systems have
been developed, usually for the soils of one country. Other systems purport to be
internationally applicable, such as Soil Taxonomy (Soil Survey Staff 1996),
promoted by the United States and the FAO-Unesco Classification (FAO-Unesco
1988), promoted by the Europeans. In Australia, the new Australian Soil
Classification (Isbell 1996) supersedes the previously used Great Soil Group
Classification (Stace et al. 1968). However, many of the highly prized soils for
viticulture continue to be called by their Great Soil Group names, or, as in France,
by class names modified from the FAO-Unesco Classification. The more common
class names, and their cross-correlations, are given in appendix 1. These names are
used where appropriate in this topic.
All these systems are general-purpose classifications. They have limitations
when detailed information is needed about the use of a particular soil for the
specific purpose of viticulture. Therefore, it is important always to describe a soil
in situ and to measure the key physical and chemical properties of that soil. These
data should be stored in a spatially referenced database, such as a Geographical
Information System (GIS) (section 8.2.1).

lower horizons in which these materials accumulate are called illuvial . The nota-
tion of A and B is used for the eluvial and illuvial horizons, and C horizon is used
for the parent material, as shown in figure 1.2. Organic litter on the surface, not
incorporated in the soil, is designated the L layer. Details of soil horizon nomen-
clature are given in specialist topics, such as the Soil Survey Manual (Soil Survey
Division Staff 1993) and the Australian Soil and Land Survey Field Handbook
(McDonald et al. 1990).
Soil formation or pedogenesis is normally more complicated than the simple
sequence in figure 1.1 suggests. Many soils have undergone successive phases of
development as a result of changes in climate and other environmental factors over
time. Such soils are polygenetic in origin. In other cases, two or more layers of dif-
ferent parent material, created at different times in the geological history of a site,
may be found in one soil profile. Soil formation can also be markedly influenced
by human activity. Around old settlements, people frequently deposited domes-
tic and animal waste to increase soil fertility. Such soils are usually rich in organic
matter and are called plaggen soils. Plaggen soils are common in European vine-
yards.