World’s Soil Resources

15.6.3 | Case study two: Soil management challenges in southwest Western Australia
The southwest of Western Australia is dominated by ancient landscapes and widespread sandy soils that
are strongly weathered. By world standards, the soils are infertile and have a range of physical and chemical
constraints to plant growth. During the last one hundred years, large areas have been cleared for agriculture.
The original perennial, deep-rooted vegetation has been replaced with shallower-rooted annual crops and
pastures. Despite significant soil constraints, extensive cropping and pasture systems have developed,
benefitting from the existence of regular winter rains. The farming systems generally operate with low inputs
of fertilizer, farm chemicals and soil ameliorants. Despite this, the region generates a large proportion of
Australia’s agricultural exports.
The serious soil management challenges of the region are reasonably well understood and it is clear that
the pressures of climate change and degradation of soil resources are combining to threaten the viability of
many agricultural businesses. This case study focuses on just a few of the soil management challenges. The
account is based almost exclusively on the comprehensive report card for sustainable natural resource use for
agriculture (DAFWA, 2013).
The climate of southwest Western Australia is changing and over recent decades mean temperatures have
risen and annual rainfall has declined (Figures 15.3(a) and (b)). The pattern of rainfall is also changing with
declines in autumn and winter rainfall and increases in spring and summer rainfall. Predictions indicate that
these trends will continue and in the short term, year-to-year climate variability may be more important for
agriculture than the longer term trends.
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
500
in the Southwest Pacific