Dryland salinity

Much of the hoped-for success of deep-rooted perennials in reducing the eventual extent of dryland salinity in Australia will depend on the farm-level economic performance of the available perennial-based farming systems. A diverse range of factors contributes to this economic performance, including short-term production-related issues, dynamic factors, sustainability factors, risk factors and whole-farm factors. Although some examples of profitable perennial-based farming systems can be identified, they are limited to particular niches in particular regions, which tend to be higher rainfall regions. For the great majority of land that is at risk of salinisation, no profitable perennial plant options are currently available. The benefits of perennials for on-farm salinity prevention are likely to be of secondary importance in determining their economic attractiveness to farmers. A case study is presented for lucerne (Medicago sativa L.) in the southern region of Western Australia. Lucerne appears likely to be profitable in suitable environments, even without considering salinity-related benefits. However, further improvements to its economic performance are needed if it is to be adopted voluntarily on a scale that would address the bigger, catchment-level problems such as river salinity and flooding risk. Policy implications of these findings are discussed.

Viewed in international terms, Australia is endowed with abundant energy resources and large land area, although much of the land is semi-arid and has low potential for agricultural production. This relatively optimistic picture must be moderated by four factors as follows: world greenhouse politics, future oil availability, widespread landscape problems in agricultural regions and declining economic fortunes of rural communities.

Groundwater chemistry was evaluated from 25 deep bores and 58 shallow piezometers. Groundwater in the fractured-bedrock aquifer is dominated by Mg and SO4 ions. Reactions within the colluvium include ion exchange of calcium for sodium in basal clays; dissolution of sodium chloride from dust-derived salt particles in the clay-rich colluvium; and microbiological reactions. Bivariate plots of sodium-versus-chloride and sodium-versus-calcium indicate that cation-exchange reactions occur in the colluvium. On the basis of hydrochemical modeling, it is concluded that the observed chemistry in the colluvial aquifer cannot be accounted for by evaporative concentration. Le chimisme de l'eau souterraine a étéétudiéà partir de 25 forages profonds et de 58 piézometres peu profonds. L'eau souterraine d'un aquifère fracturé de socle est marquée par les ions Mg et SO4. Les réactions dans les colluvions mettent en jeu des échanges de calcium avec le sodium des argiles de base, la dissolution du chlorure de sodium provenant de particules de poussière produite par le sel dans les colluvions argileuses, et des réactions microbiologiques. Des corrélations sodium – chlorure et sodium – calcium montrent qu'il se produit des réactions d'échange de cations dans les colluvions. Le recours à une modélisation hydrochimique conduit à conclure que le chimisme observé dans l'aquifère colluvial ne peut pas être expliqué par une reconcentration par évaporation. Del estudio de la química de las aguas subterráneas en 25 sondeos profundos y 58 piezómetros superficiales, se deduce que los iones dominantes en el acuífero fracturado son Mg y SO4. Las reacciones con los depósitos coluviales incluyen intercambio iónico de calcio por sodio en las arcillas basales, disolución de cloruro sódico procedente de partículas de sal en la zona coluvial rica en arcilla, y reacciones microbiológicas. Los diagramas de sodio-cloruro y sodio-calcio indican que las reacciones de intercambio de cationes tienen lugar en el coluvión. Basándose en un modelo hidroquímico, se concluye que la química observada en el acuífero coluvial no puede deberse a concentración por evaporación.

Solutions are tested in a physical sense, for a set of future and interconnected future challenges that centre on the losses of landscape function in Australia's farming zones, the possible depletion one human generation away of domestic oil stocks, and greenhouse gas emissions from the fossil energy sector. A partial solution to these intertwined problems could be the establishment of

Oil mallees are one of the preferred options to combat dryland salinity in the Western Australian wheatbelt, but their economics are uncertain. We compare three scenarios: on-farm mallee oil production, industrial oil and wood-based electricity production, and a combined oil, electricity and activated carbon system. Only the third option has any serious chances of being a profitable venture, with the

Australia is currently experiencing a process of escalating ecosystem degradation. This landscape degradation is associated with many outcomes that may directly or indirectly impact on human health. This study used a Bayesian spatial method to examine the ...

By 1994, an estimated 1.8 million hectares of cleared land in Western Australia was affected by secondary dryland salinity to some extent. The area affected is likely to double in the coming 20 years. The cause of this salinity is excessive recharge under traditional agriculture, leading to rising groundwater levels. Monitoring changes in groundwater levels is helpful in indicating the degree of threat to agricultural land and public assets. Many researchers have studied groundwater level rises and attempted to explain them ...

Clearing of trees and native vegetation over the past 160 years has led to increasing rates of dryland salinization in the Goulburn-Broken Catchment area. In its dryland section, within the Goulburn Highlands, South West Goulburn, and the Broken Highlands subcatchments, hydrologic balance exists. But in the Riverine Plains comprising the Goulburn and Broken Plains sub-catchments, where average annual rainfalls are

Meshed with the bio-physical and economic dimensions of rural land-use is a social dimension. Understanding the social and economic dimension of rural communities is critical if agencies are to develop effective policies and programs to improve natural resource outcomes. In this paper, we draw on research of the Boorowa community, located in the south-west slopes of New South Wales, to

Abstract  Previously existing sources of data regarding mosquitoes in inland areas of south-west Western Australia are few and qualitative in nature. This is the first attempt to quantitatively investigate mosquito fauna in this region. The existing data are reviewed and compared with the results of the quantitative surveys presented in this paper. Temporal comparisons appear to indicate that mosquito community structure in the region may have changed since the initial surveys in the 1950s from a combination of freshwater-breeding species towards a strong dominance of Aedes camptorhynchus (Thomson), a major vector of Ross River virus in southern Australia. It is speculated that this shift may have been brought about by the increasing area and severity of dryland salinity in the region over the last century, and also may increase the potential for Ross River virus disease transmission.