Agriculture Reference
In-Depth Information
For management purposes, classiÝcation needs to account for the thickness and severity of acid
sulfate soil horizons present, whether as actual or potential acid sulfate soil. These require speci-
Ýcation of sulÝde content, lime requirement, and an assessment of risk based on proposed volume
of soil disturbance. This information is used to develop comprehensive, technically valid soil
management plans.
Since the 1990s, this demand has led to the establishment of acid sulfate soils mapping
programs, training programs on identiÝcation and management, and policy development to
regulate use of these high-risk soils. These activities are most advanced in the states of New
South Wales (Naylor et al., 1995) and Queensland, and include the establishment of advisory
committees and acid sulfate soil-speciÝc planning policies/regulations, technical management
guidelines, and training programs. The mapping programs aided by research have led to a vast
increase in knowledge about AustraliaÔs acid sulfate soils. This was not available when the
Australian Soil ClassiÝcation of Isbell (1996) was being constructed, but provides the basis for
improvement in the future. Such new information (e.g., Ahern et al., 2000; Slavich, 2000) relates
to better methods of Ýeld assessment, the hydrological and chemical changes and processes that
occur following drainage or remediation, the variety of sedimentary facies possibly involved,
improved methods of soil testing, and recognition of distinctions in various sulfur minerals and
organic peats formed under contrasting pH and redox conditions. Acid sulfate soils with sapric
material and intense reducing conditions (low redox potentials) have been identiÝed in South
Australia (Fitzpatrick et al., 1993). These conditions appear to originate from high input of
detritus from seagrass and mangroves in the low energy environments and increased nutrient
loads. This information was used to amend Soil Taxonomy (Fitzpatrick et al., 1993) and to
develop preliminary proposals to modify the Australian Soil ClassiÝcation (Isbell, 1996). In this
case, soil properties and processes must be better understood if effective approaches to manage-
ment are to be developed and changes to classiÝcation systems made.
FUTURE DIRECTIONS
In Australia, land managers, planners, and researchers often operate with poor spatial informa-
tion on soil, and this limits their capacity to analyze and implement optimal systems of land use.
Conventional survey programs and national soil classiÝcation schemes have not always provided
appropriate information at relevant scales. New demands for information in Australia are exposing
further weaknesses in the land resource survey coverage and the communication capacity of existing
soil classiÝcation schemes.
Dryland salinity, soil acidiÝcation, declining stream water quality and a range of other emerging
problems have created a strong environmental imperative for large-scale land-use change in Aus-
tralia. Government, industry, and community groups wish to identify and analyze proÝtable pro-
duction systems that alleviate serious land and water degradation. Likewise, a range of other natural
resource management issues relating to international agreements (e.g., Kyoto Protocol, Montreal
Convention), environmental regulation, and trading systems (e.g., for water, salt, carbon) are
stimulating an unprecedented demand for analysis and prediction of soil and landscape function.
Methods of landscape analysis with a process-basis are required to provide spatial and temporal
predictions of properties controlling the function of agro-ecological systems. There is a need to
develop improved simulation models depicting spatial and temporal processes; measurement and
prediction technologies to provide appropriate model inputs; and monitoring and experimentation
to validate modeling predictions.
Both special-purpose and general-purpose soil classiÝcation systems are predicted to have a
role in these developments, but in generally different directions. Like the examples presented in
this chapter (Table 9.5), the special-purpose classiÝcation schemes will continue to be developed
to meet the speciÝc and practical needs of users of soil information. The general-purpose schemes,
