Agriculture Reference
In-Depth Information
1980) and the Canadian system of soil classiÝcation (Canada Soil Survey Committee, 1978) both
place strongly gleyed podzols with Podzols, rather than with Gley Soils. Thus the precedent is
established that, for some soils, features other than gleying are marked so that they determine order
assignment. The New Zealand Soil ClassiÝcation applies this not only to the Podzols but also to
nine other orders.
FIELD ASSIGNMENT TO SOIL CLASSES
Principle 5 addresses a dilemma faced in the development of any soil classiÝcation concerning
the choice of differentiae. Should they be based on high-precision laboratory-derived measurements
or on lower-precision Ýeld-based measurements or observations? Laboratory-based attributes pro-
vide for more certainty and reproducibility in assignments. The disadvantage is that assignment
decisions frequently cannot be made in the Ýeld and must await the results of costly laboratory
procedures. As a consequence, few pedons in a survey area can be conÝdently assigned to the
classiÝcation. Although Ýeld-based differentiae have lower precision, they enable frequent Ýeld
assignment of pedons.
In the development of the New Zealand Soil ClassiÝcation, it was judged that better character-
ization of survey areas would result from frequent assignments based on lower-precision Ýeld
differentiae than from few assignments based on higher-precision laboratory differentiae. ConÝ-
dence that this was possible was based on improved deÝnition of morphological properties in New
Zealand (Milne et al., 1991; GrifÝths et al., 1999) that has resulted in more reproducible Ýeld
measurements.
This principle was adhered to in the deÝnition of most classes, but it was found necessary to
include pH, phosphate retention, Ýne earth dry bulk density, and electrical conductivity as differ-
entiae. Where possible, lab-based differentiae were used to back up Ýeld-based differentiae. For
example, in the deÝnition of allophanic soil materials, Ýeld differentiae involving stickiness, soil
strength, sensitivity, and the reactive-aluminium test were backed up by an alternative: phosphate
retention limit.
NOMENCLATURE
In the 1960s, the New Zealand genetic soil classiÝcation was recast as the New Zealand
Technical ClassiÝcation (Taylor and Pohlen, 1968). It did not endure, largely because of an
unfortunate nomenclature. The elegant nomenclature of Soil Taxonomy is efÝcient and connotative,
and suitable for an international system, but the New Zealand Technical ClassiÝcation presented
an unnecessary initial barrier for a national audience, which restricted effective use to the specialist.
Consequently it was decided that the nomenclature of the New Zealand Soil ClassiÝcation
should be acceptable to nonspecialists, and even to the general public. Names are obviously
important in marketing a product for which acceptability depends on initial appeal and public
exposure. An elitist scientiÝc nomenclature was to be avoided, especially at order level. It was
noted that, after all, English is now the international language of science and diplomacy. Accord-
ingly, a system of connotative, common, English words was used in an initial draft of the classi-
Ýcation. It was found, however, that common English words could easily create confusion between
common and technical uses of the same word.
The nomenclature of the published classiÝcation represents a somewhat uneasy compromise
between apparently appealing technical names and simple or modiÝed common English words.
Names such as ÑBrown SoilsÒ are differentiated as nouns by capitalization. Other names such as
ÑAllophanic SoilsÒ are clearly not based on connotative recognizable English words. In this case,
