Salinity in Australia
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Soil salinity and dryland salinity are two problems degrading the environment of Australia. It is a concern in most states, but especially in the south-west of Western Australia.
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The Eastern Mallee and the Western Mallee are areas that are prone to salinity with little remedial action being undertaken to rectify the problem. Lands surrounding Lake Bryde-East Lake Bryde and Dumbleyung Lake have also been affected.
In the Murray River valley irrigation has caused salinity problems. Land surrounding the town of Werrimull in the northwest of Victoria have been affected by salinity due to land clearing.
The problem is a land management issue, similar to severe drought in Australia and to Australia's efforts to control exotic weeds and pests, both threatening yields from agriculture in Australia.
[edit] Process
Some of the salts originate from marine sediments, as Australia once contained inner salt seas that over thousands of years, especially during the drying out of Australia, were removed leaving deep traces of salt water in aquifer like salt water tables underground. Though, most of the salt areas have been deposited in rainfall over thousands of years. Where topographic and climatic conditions are right, the salts have accumulated to high levels. Prior to English settlement in 1788, groundwater levels were in equilibrium; the salt water of the underground tables never rose to ground level due to absorption by native flora growing on the surface.
After the clearing of the native vegetation for European-style agriculture, excess water leached down into the saline layers of soil, and allowed them to move, sometimes into waterways or to the soil surface.
[edit] Effects
Over time this process caused the thin top-soil layers to become irreversibly salty, and no longer suited for agriculture. In 2001 an estimated 2.5 million hectares of land had become salinised since the introduction of European farming methods. Fact|date=January 2008}}
Muehlenbeckia horrida subsp. abdita, commonly known as the Remote Thorny Lignum, is a critically endangered species due to its intolerance to salinity.
[edit] Impact reduction
Where the land is not yet affected by salinity, it is sometimes possible for farmers to reduce the speed at which land becomes saline by re-establishing perennial plants, including perennial pastures, shrubs and trees.Where the land is already affected by salt, a number of salt-tolerant species such as Atriplex amnicola, are used to support livestock.
Another such species, the Saltgrow, a hybrid gum tree, is being utilized within Australia to try to reverse damage within affected high-salinity areas. The tree has been highly successful, and has been attributed to be able to completely remove salinity within damaged areas and allowed new grasses and shrubs that are not salt resistant, to grow. Economically, such a plant would be a viable choice as well, as the tree can be used for wood chips, paper and is being experimented. Alternatively, many farmers in Western Australia and parts of South Australia are attempting to return salt-affect land to traditional agricultural production by digging deep-open drains.
A number of organisations are seeking ways to reduce the impact of salinity on Australian agriculture, including the Cooperative Research Centre for Plant-Based Management of Dryland Salinity. Greening Australia and Australian Centre for Plant Functional Genomics have also implemented projects to alleviate salinity in Australia.
[edit] See also
[edit] References
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[edit] External links
- Australian Bureau of Statistics 2004 Year book
- Cooperative Research Centre for Plant-Based Management of Dryland Salinity
- David Pannell's publications of economic, social and policy aspects of dryland salinity
- Department of the Environment and Heritage
- National Dryland Salinity Program
- Extent of salinity in Australia
