Soils of South Australia
South Australia’s soil diversity can be attributed to five dominant factors:
- Parent material – in South Australia, the main parent materials are ancient basement rocks, a range of younger, often unconsolidated sediments laid down by wind and water, and older soils.
- Climate – climatic conditions affect the rate of physical, chemical and biological soil forming processes. Past climates have led to extensive deposition of wind or waterborne sediments within which a distinctive range of soil types has formed. Climatic factors affecting soil formation are rainfall, wind, wetting and drying, temperature, streams and floodwaters, and lakes, lagoons and marine environments.
- Topography – the position of a soil in the landscape influences different rates of erosion and deposition, drainage, and leaching. Soil depth is determined predominantly by position in the landscape.
- Biological influences – soil organisms, plants, growing season, nature of organic matter and other factors that affect the proliferation of soil organisms. In turn, these influence mineral weathering, nutrient availability, and organic matter formation and decomposition in soils.
- Time – the longer soil materials are acted upon by soil-forming processes, the more weathered, leached and infertile they become. Australia is geologically very stable and has not experienced mountain-building, glaciation, or widespread and frequent flooding for many millions of years so no unweathered, reactive materials from newly exposed rock have been widely deposited in more recent geological times.
South Australian soils are largely formed from ancient, highly weathered materials. Therefore they are often inherently infertile and fragile and it is important they are carefully managed. The importance of appropriate soil management is emphasised by the fact that soil is effectively irreplaceable, given its very slow rate of natural formation.
Find out more:
The Soils of Southern South Australia (2009) publication provides a comprehensive documentation of the State’s soil resources. It is designed to build knowledge and understanding of soils for those involved with managing, planning, research, education, ecology, industry development, or anyone interested in improving the management and condition of our precious soil and land resources.
Factsheets summarising this publication are available from here: