Salt-affected soils of south-west Australia: implications for deep drainage
Bell, R.W., Mann, S. and Raphael, C. (2008) Salt-affected soils of south-west Australia: implications for deep drainage. In: 2nd International Salinity Forum: Salinity, Water and Society – Global issues, local action, 31 March - 3 April, Adelaide, Australia
Secondary salinity already covers about 10 % of the Western Australian (WA) wheatbelt, and could reach 23 % if action is not taken to arrest its spread (McFarlane et al., 2004). Engineering solutions such as deep drainage are under consideration for rehabilitation of a range of salt- and waterlogging affected soils (Dogramaci and Degens, 2003). Underlying the installation of deep drainage is the assumption that damage to salinised, waterlogged soils is largely reversible when water tables are lowered. The recovery of the costs of drainage depend on being able to improve soil productivity and generate increased income from the drained land. Alternatively, for natural resources managers, the justification for a deep drain may be to allow the restoration of the vegetation communities that existed on the site prior to salinisation. Productivity on salinised soils may also be achieved by planting of saltland pastures using halophytic species. This strategy has been shown to decrease water tables (Barrett-Lennard and Malcolm, 2003), but effects on recovery of soil properties has not been investigated.
Given the diverse nature of soils and climatic zones subject to salinity and waterlogging in south-west WA, the expected responses in soil productivity to drainage will vary. The texture, structure, and sodicity of the profile will be significant in determining how easily entrained salt is leached. Recovery of soil structure and soil organic matter levels will also have a significant bearing on soil productivity after draining. This paper reviews the properties of naturally saline soils, and of soils that have experienced secondary salinisation and waterlogging. In the full paper, data is also presented on soils before and after deep drains were installed. It also highlights crop productivity after deep drainage, and the value of treatments to accelerate the return of soil productivity to acceptable levels for sustainable and profitable land use after draining.
|Publication Type:||Conference Paper|
|Murdoch Affiliation:||School of Environmental Science|
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