Our soils, landforms and vegetation have co-evolved over millions of years. Their health and condition are inextricably linked. Soil health has a strong influence on the growth and condition of all types of vegetation. Conversely, changes to vegetation caused by fire, clearing, grazing or harvesting affect the condition of our soils.
The soil system performs many functions. It:
- produces biomass
- stores and filters water
- stores and cycles nutrients
- is a large carbon store
- hosts biodiversity
- provides raw materials (e.g. clay, sand, gravel)
- stores our geological, paleontological and palaeontological heritage.
Soil is essentially a nonrenewable resource, because it forms and regenerates very slowly, but can degrade rapidly. Some types of degradation, such as nutrient exhaustion, can be corrected, but this correction may be very costly. However, other forms of degradation, such as soil erosion, are difficult to remedy. Prevention is the key.
Soil is effectively privately owned across much of Australia. However, the influence of healthy soils on the environment as a whole—such as improving water quality, protecting biodiversity and mitigating excess greenhouse gases (GHGs)—means that soil is also a large public good.
Most of Australia’s soils are ancient, strongly weathered and infertile. Some areas have younger and more fertile soils; these mainly occur in the east. Australian soils have many distinctive features. Surface layers have low levels of organic matter, and are often poorly structured, a condition made worse by historical agricultural practices. Soils affected by salt—either now or in earlier geological times—cover large portions of the arable lands of our continent. We also have large areas of cracking clays, which are relatively fertile but have physical limitations that reduce agricultural options and affect key infrastructure. These constraints and their interactions with climate have made it difficult to develop sustainable systems of land use.