World’s Soil Resources

Figure 15.5 Agricultural lime sales 2005–12 in the south-west of Western Australia based on data for 85–90 percent of the market.
Other soil management challenges
A range of other serious threats to soil function are prevalent in southwest Western Australia. Dryland
salinity has been accelerated and enlarged by widespread clearing and land-use change. The problem affects
agricultural land, water resources, natural biodiversity and the built environment with an economic cost of
hundreds of millions of dollars annually. Currently, more than 1 million ha are severely salt-affected (McFarlane,
George and Caccetta, 2004; Furby, Caccetta and Wallace, 2010). Dryland salinity has expanded in most of this
region since 1998, especially following episodic rainfall events (George et al., 2008a; Robertson et al., 2010). In
areas cleared and developed for agriculture after 1960, most water tables continue to rise, despite a decline
in annual rainfall. Dryland salinity is a potential threat to 2.8–4.5 million ha of productive agricultural land
(George et al., 2005). The long-term extent of salinity may take decades to centuries to develop (George et al.,
2008b). The areas with the highest dryland salinity risk occur mostly in the highly productive, medium to high
rainfall dryland agricultural areas. Management to contain or adapt to salinity is technically feasible using
plant-based and engineering options, though recovery is economically viable in only a few areas (Simons,
George and Raper, 2013).
Wind erosion is a critical issue for the livestock and grain industries. Maintaining sufficient, stable soil
cover throughout the year is the challenge and this is difficult in a variable and generally drying climate. Water
erosion hazard during the growing season has diminished due to declining winter rains and more sustainable
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in the Southwest Pacific