Desert soils in Australia

Wind action is a dominant factor in determining the nature of soils in arid Australia. Wind strongly affects evaporation, it influences the accession of cyclic salt by the soil, and it is a powerful factor in the distribution of soil-forming materials. Desert surfaces include vegetation-covered sandhills, stony plains, and rock surfaces. It is likely that spinifex-covered sandhills were more widespread before the arrival of pastoralists in the arid and semi-arid regions. Gibber plains or stony deserts (serir) are formed by the removal of fine soil particles by wind and the leaving of polished pebble surfaces. Rock deserts (hamada) are characteristic of the Nullarbor Plain, where massive limestone outcrops.


Australians, like most Americans, have become generally aware only recently of the seriousness and extent of soil erosion. The widespread deterioration and removal of natural vegetation cover are largely responsible. The production of wheat on dry marginal areas, the extensive use of the fallow system, and the occurrence of dry years have provided the combination that permits dust storms to carry away the top soil from the subhumid interior farming districts. Overgrazing by sheep, rabbits and other livestock has removed the grass and brush cover that once protected the soil. Careless cultivation and fallowing of the rich red soils of the Darling Downs have led to their serious gullying, even on gentle slopes. Apple production on steep slopes in Tasmania has resulted in serious sheet wash and gullying of the podsol soils. Many soils in the Eastern Highlands erode seriously after the removal of timber cover.

Dust storms and muddy streams, gullies and rock exposures, reduced yields, and smaller carrying capacities are the usual evidences of soil destruction. Very little has been done thus far by either individuals or government to check the losses on a large-scale basis.

No comments: