Agriculture Reference
In-Depth Information
Table 9.4
Key to the Soil Groups
a
within the Deep Sands Soil Supergroup (Western Australia)
Calcareous within top 30 cm of surface, and usually throughout:
Calcareous deep sand
Yellow within top 30 cm, ironstone gravel common at depth:
Yellow deep sand
Brown within top 30 cm:
Brown deep sand
Red within top 30 cm:
Red deep sand
Gravelly below 15 cm and gravels a dominant feature of the profile, with
a minimum gravel layer requirement of 30 cm thick and > 20% ironstone
gravels starting within the top 80 cm. White, grey or Munsell value of 7
or greater (pale yellow) within top 30 cm. The sandy subsoil matrix may
be colored:
Gravelly pale deep sand
White, grey or Munsell value of 7 or greater (pale yellow) within top 30 cm:
Pale deep sand (
Figure
9.3)
Other deep sands:
(use DEEP SANDS Supergroup)
a
Adapted from Schoknecht (2001)
The Soil Groups have proven to be a very useful and practical tool for describing and commu-
nicating soil information. The terms used are simple and easy to understand for most people. The
system is not designed to replace the national classiÝcation system (Isbell, 1996), but is a user-
friendly tool and complements it, as shown in Figure 9.3.
SPECIAL-PURPOSE SOIL CLASSIFICATION
SYSTEMS
The following case studies have been selected to illustrate some of the developments in devising
special-purpose soil classiÝcation systems in Australia, to solve a wide range of practical problems
for end-users. The case studies discussed are selective, but various other classiÝcation systems have
also been developed and summarized in Table 9.5. These technical or special-purpose soil classi-
Ýcation systems rely mainly on soil attributes, but rarely also include other important environmental
aspects such as geology, terrain, vegetation, or hydrology, which may be relevant to a particular
end-user (Table 9.5). The combined use of soil and other information assists the understanding of
how soils vary in landscapes so that strategies can be developed for managing both spatial and
temporal changes within them.
Engineering Applications: Optical Fiber Cables
This case study summarizes the development of a suitable special-purpose soil classiÝcation
system to minimize soil damage to the Australian telecommunication optical Ýber cable network
(Fitzpatrick et al., 1995; 2001). Some types of optical Ýber cables can develop transmission faults
by soil movements caused from soil shrink-swell properties, and corrosion from saline soil solutions.
Such faults are very costly to repair and, if avoided, can save millions of dollars.
Field and laboratory investigations on a representative range of soils known to cause faults in
optical Ýber cables were undertaken (Fitzpatrick et al. 1995). Close liaison between soil scientists
and engineers ensured that research investigations led to the development of a practical soil
classiÝcation system comprising a user-friendly 1Ï10 rating of soil shrink-swell risk, which can be
derived logically by using a series of questions and answers set out in a manual titled: ÑSoil
Assessment Manual: A Practical Guide for Recognition of Soils and Climatic Features with Potential
to Cause Faults in Optical Fibre Cables.Ò The manual describes practical, surrogate methods to
assist engineers in estimating soil shrink-swell indices by using either published soil maps in ofÝce
assessments (Atlas of Australian Soils, Northcote, 1960Ï1968) or by undertaking simple visual
observations and chemical measurements of soil properties in the Ýeld (Table 9.5). This information
is incorporated in a planning operations and procedure manual for engineers.
Guided by the Manual, telecommunication engineers have learned how to use pedological,
climatic, and soil chemical information to, Ýrst, avoid the shrink-swell and corrosive soils along
