Thursday, April 26, 2007
Salt in the Soil = Economic Problems
Salt, is another huge problem for Australia’s soil, Jared Diamond says in Collapse. Just as the first farmers were not aware of the nutrient poverty in Australia’s soils, so they were not aware of all the salt in the ground.
In southwestern Australia’s wheat belt, the salt in the ground comes from its having been carried inland over the course of millions of years by sea breezes of the adjacent Indian Ocean.
In southeastern Australia, another prominent wheat belt, the basin of Australia’s largest river system, the Murray and Darling Rivers, lies at such a low elevation that it has been repeatedly inundated by the sea then drained, leaving much of the salt behind.
Another low-lying basin inland, was formerly filled by a freshwater lake that did not drain to the sea, but became salty by evaporation like Salt Lake in Utah and the Dead Sea in Israel, and eventually dried out, leaving salt deposits that were carried by winds to other parts of eastern Australia.
Some Australian soils contain more than 200 pounds of salt per square yard of surface area. Salt is easily brought to the surface by land clearance and irrigation agriculture, resulting in salty top soils in which no crop can grow. More about Australia, Monday; tomorrow: Friday Funnies.
In southwestern Australia’s wheat belt, the salt in the ground comes from its having been carried inland over the course of millions of years by sea breezes of the adjacent Indian Ocean.
In southeastern Australia, another prominent wheat belt, the basin of Australia’s largest river system, the Murray and Darling Rivers, lies at such a low elevation that it has been repeatedly inundated by the sea then drained, leaving much of the salt behind.
Another low-lying basin inland, was formerly filled by a freshwater lake that did not drain to the sea, but became salty by evaporation like Salt Lake in Utah and the Dead Sea in Israel, and eventually dried out, leaving salt deposits that were carried by winds to other parts of eastern Australia.
Some Australian soils contain more than 200 pounds of salt per square yard of surface area. Salt is easily brought to the surface by land clearance and irrigation agriculture, resulting in salty top soils in which no crop can grow. More about Australia, Monday; tomorrow: Friday Funnies.
