The Australian Academy of Science describes salinity as “the white death”.
According to the Academy “The term ‘dryland salinity’ strikes fear into the hearts of many Australian farmers. Some call it the white death because it conjures up images of lifeless, shining deserts studded with dead trees. Fears of the ‘white death’ seem justified. Dryland salinity currently affects about 2.5 million hectares of land, mostly in southern Australia and causes damage totalling $270 million each year.”
“Every day, another chunk of land about the size of a football field is quietly drowning in salt. By the time a baby born today reaches the age of about 30, a total area almost equivalent in size to the State of Victoria will have gone under: dead, useless, ugly, awkward, embarrassing and depressing.” Michael Archer and Bob Beale, Going Native, 2004
Salinity is a big problem in Australia. Some 2.5 million hectares of rural land are already affected by salinity, and there is the potential for this to increase to 15 million hectares. Much of this is Australia’s most productive agricultural land. The area damaged by salinity to date represents about 4.5 percent of present cultivated land.
There are lots of different definitions of a saline soil throughout the world. Generally in Australia, a soil is classified as saline when the soil chloride content is greater than 0.1% .
The extent of saline soils in Western Australia has been estimated based on the definition that a soil was saline when its salt content was sufficient to reduce the yield of normal crops and pastures by 50%.
Alberta Agriculture consider a soil saline when normal crop and pasture yield is reduced by 25%.
Yield reduction due to salinity is compounded by the interaction of salinity with waterlogging. Plants in waterlogged situations can tolerate far lower levels of salinity than can plants in well-drained, aerated situations.
Dryland salinity affects all areas of Australia where there has been a broad-scale change in land use and where there is a significant salt store in the soil profile. The area of agricultural land affected is the only available indicator of the spatial extent, however it must be noted that the impacts can extend downstream from the actual area affected.
At present the area of surface water systems that have been affected still coincides with the extent of salinised land to a large degree.
Clearing deep rooted bushland and replacing it with shallow rooted pasture grasses and crops has led to more rainwater making it’s way into the groundwater.
Compare the map of dryland salinity with the satellite image showing the area of native vegetation cleared in red.
Available data on the area of agricultural land affected by dryland salinity varies with scale. Good data is available on a local scale for many catchments, but state and national estimates are just that - estimates.
Of the approximate 3.31 million hectares of cleared land in the south-western region of Western Australia, 8.3% (approximately 273,800 hectares) was affected by salinity in 1994. It has been projected that by 2010-2020 some 18% of the region (595,500 hectares) will be affected by salinity (depending on the level of rainfall). It is also estimated that there is the potential for up to 25% of the region (820,000 hectares) to eventually be affected by salinity. These are scary statistics and you only have to fly across the region in a plane to recognise the extent of the problem.
