Agriculture Reference
In-Depth Information
challenged as being largely unnecessary; numerical analysis of soil data, it was argued, would
replace the former functions of soil classiÝcation.
In reply (Hewitt, 1987), it was noted that classiÝcation is basic to human thought processes.
We observe similar objects and Ýnd it efÝcient to group them and provide a label as a mental key
to the class. For example, we label the group of objects with a Þat surface and four legs ÑtableÒ.
Likewise the word ÑsoilsÒ assumes classiÝcation. A grouping of soil entities together constitutes a
kind of soil. Our formal soil classiÝcation is a codiÝcation of these Ñsoils,Ò deÝned so that we can
all communicate efÝciently. Soil classiÝcation is, therefore, primarily designed for human cognition.
Data is the currency of computers, and no matter how sophisticated the analyses, the results must
be summarized and reduced to make the results comprehensible for humans. A soil classiÝcation
provides a framework that greatly facilitates understanding and application of the results of numer-
ical analysis.
With this in mind, four purposes were given priority in development of the New Zealand Soil
ClassiÝcation:
1.
Communication and understanding.
Soil scientists and allied specialists are able to efÝciently
carry on informed discussion about a set of soils when there is prior agreement on concepts and
deÝnitions. As well as facilitating specialist communication, there is a pressing need to make soil
information more accessable to nonspecialists. Soil classiÝcation is the human face of soil science,
and often a soil name is the Ýrst contact the nonspecialist or nonscientist will make with it. When
it is learned that a soil name can be given to a soil, and what that name implies, new vistas of
understanding open up.
2.
Soil survey support and application.
Soil survey is becoming more quantitative with greater focus
placed on soil attributes rather than classes. However, the traditional role of soil classiÝcation to
support soil survey and interpretations, as promoted by Soil Taxonomy (Soil Survey Staff, 1999),
will remain as far as the need for human understanding of the process and results remain. There
will always be a need to express an overview of soil entities.
3.
Key soil database Ýeld.
Soil classiÝcation provides a frequently used key when using the New
Zealand National Soils Database, particularly when deÝning the data sets relevant to a query,
summarizing the results, and checking the regional and national representativeness of data.
4.
New synthesis of knowledge.
The new classiÝcation provides a synthesis of several decades of
intensive research on New Zealand soils. Providing a statement of our understanding or conception
of the natural soil system would be sufÝcient reason alone to develop a new national soil classi-
Ýcation. This is work that holds cultural as well as scientiÝc values. Synthesis is extremely
important in science. It is our responsibility to push our general model of the soil system so that
our minds and understanding do not become reduced to mere software; reduced to match our
neatly regimented data sets.
OUTLINE OF THE PRINCIPLES
To accomplish these purposes, the following principles guided development of the New Zealand
Soil ClassiÝcation:
1.
The classiÝcation should be hierarchical, providing ascending levels of generalization.
2.
The grouping of soils into classes should be based on similarity of measurable soil properties,
rather than presumed genesis.
3.
Classes must be designed to allow the greatest number and most precise accessory statements to
be made about them, consistent with their level in the hierarchy.
4.
Differentiae should be based on soil properties that can be reproducibly and precisely measured
or observed.
5.
Differentiae should, where possible, allow Ýeld assignment of soils to classes, either directly or
by tested inferences.
