Comparing the recent basaltic soils of parts of NSW with deeply weathered soils of Western Australia

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Comparing the recent basaltic soils of parts of
NSW with deeply weathered soils of Western
Australia
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Australian soils tend to be

• Old
• Salty
• clayey - except in the west of the continent
  where they tend to be sandy
• Acidic
• nutritionally and organically impoverished
• structurally challenging

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Basaltic soils of East Coast

• Pockets of recently formed basaltic soils exist
  in parts the East Coast of Australia.
• Recent volcanic activity -oldest extinct volcano
  found in Northern Queensland 33 mil yrs oldn
  Youngest in Victoria 10 mil yrs old (Australia
  moved over hotspot)
• Eg Mt Warning Tweed Coast is a remnant of a
  volcano that spewed lava around 20 million years
  ago.

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Australian plate is moving North at around 7cm
per yr
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Basaltic Soil

• Parent rock basalt (mafic)
• Fine textured
• Deep red/ chocolate colour
• High in nutrients (high level of calcium
  phosphate which acts like fertilizer)
• Very fertile

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Deeply weathered laterite soils of Western
Australia

• Parent rock generally granite (felsic)
• Laterite (soil residue composed of secondary iron
  oxides)
• Coarse texture
• Old (long time of weathering, leaching)
• Nutrient poor
• Colour red (due to oxidation of iron)
• Rich in Aluminium and Iron

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• Australian soils have been subject to extensive
  degradation due to such practices as
  overgrazing, over cultivation, tree clearing, and
  irrigation.
• A continuous cover of vegetation on the soil
  results in the most stable situation. However
  this is not possible for many land uses,
  particularly those in the agricultural sector.
• Major forms of degradation
• wind and water erosion
• reduced fertility because of nutrient loss
  physical breakdown of soil structure soil
• acidification
• salinisation

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Soil Erosion
Is the movement of particles Of soil, surface
sediments and rocks by the action of water,
glaciers, winds, waves and so on
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Wind erosion
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Sheet erosion

• Removal of uniform layer of soil over a wide
  area. Usually caused by rainfall (rain drop
  splash)
• Removes the top soil layer (bulk of nutrients)

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Rill Erosion

• Numerous small channels

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Gully Erosion
Removal of soil by a concentrated flow Of water
with a sufficient velocity to cut Large channels