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

Western Australia

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

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.

Australian plate is moving North at around 7cm per yr

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

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

• 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 erosionreduced fertility because of nutrient loss physical

breakdown of soil structure soil acidificationsalinisation

Soil ErosionIs the movement of particles Of soil, surface sediments and rocks by the action of water, glaciers, winds, waves and so on

Wind erosion

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)

Rill Erosion• Numerous small channels

Gully ErosionRemoval of soil by a concentrated flow Of water with a sufficient velocity to cutLarge channels