AddThis Social Bookmark Button

Soils are a vital part of the natural environment.  They are complex entities, and many different types occur in Australia.   The different properties of soils influence the types of flora and fauna that exist on them, and the ways in which we may use them.  

The Soils Downloads page has a range of information suitable for primary, secondary and tertiary students and teachers however you may be interested to read below about the many suprising attributes of soil and to learn of the State soils.

State Soils

New South Wales - Red Chromosol
Northern Territory - Kandosol
Queensland - Vertosol
South Australia - Calcarosol
Tasmania - Ferrosol
Victoria - Mottled Brown Sodosol
Western Australia - Yellow Chromosol

A detailed description of each State soil can be found on the relevant Branch page

Soil types

  • One teaspoon of a cracking clay soil has the surface area of a football field.
  • A shrink/swell clay soil can expand/contract by as much as 30% as it wets and dries.
  • A gram of smectite (shrink/swell clay) has a surface area of about 800 m²,
  • while a gram of kaolinite (a rigid clay) only has a surface area of about 10 to 20 m²

Soils and Greenhouse

  • Organic carbon (C), present in soil organic matter, is an important global carbon pool, estimated to be 1550 Gt (1 gigatonne = 100 million tonnes). The soil organic C pool (to a depth of 1 m) is approximately three times larger than the amount of C stored in vegetation and twice the amount stored in the atmosphere [1] .  
  • Mainly because of our dry climate, organic C stocks in Australian soils are much lower than the global average, and are estimated to be about 50 Gt [2] .
  • Soil cultivation and soil degradation result in losses of organic carbon which is released as CO² into the atmosphere.  
  • Agricultural soils, mainly through the use of N fertilisers, are also significant emitters of nitrous oxide (a greenhouse gas more potent than CO²).  
  • Emissions of greenhouse gas from Australian agricultural soils accounted for 19 million tonnes of CO² -equivalent in 2003, or about 3% of the national greenhouse total for that year [3] .
  • Land clearing and overgrazing also contribute to the loss of soil carbon.
  • Improved soil management strategies such as conservation cropping and reduced grazing pressure have the potential to increase the store of soil C, thereby acting as sinks for atmospheric C.  

[1] Statistics are from Lal, R (2004).   Soil carbon sequestration impacts on global change and food security.   Science 304 1623-1627.
[2] Jan Skjemstad, CSIRO Land and Water, Adelaide.
[3] AGO, National Greenhouse Gas Inventory (2003):   http://www.greenhouse.gov.au/inventory/2003/facts/pubs/04.pdf.

Species diversity

  • A single gram of soil is estimated to contain several thousand species of bacteria
  • One square metre of soil can contain about 10 million nematodes and 45 000 microarthropods (springtails and mites).   It has more species in it than 1km²  of rainforest

Sporting soils

  • Australia's cricket pitches use a particular type of soil - black cracking clays
  • Soil science is integral to developing sporting fields and golf courses that are playable in our variable climatic conditions.

Costs

  • The annual cost to industry for acid sulphate soils management in Queenslands coastal zones is estimated at $189 million dollars.
  • National costs to the community associated with soil salinity are estimated in excess of $100 million dollars.

Issues affecting soils in Australia

Safe-guarding the health of our soils is vital to Australia's future, from environmental, social and economic perspectives. There are many issues that affect our soils and landscapes including salinity, acidity, compaction, erosion, fertility decline and loss of biodiversity.