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By Root 2085 0

included what may have been the tallest trees in the modern world (the blue gums of Victoria’s Gippsland, up to 400 feet tall), they were deceived by appearances into thinking that the land was highly productive. But after loggers had removed the first standing crop of trees, and after sheep had grazed the standing crop of grass, the settlers were surprised to discover that trees and grass grew back very slowly, that the land was agriculturally uneconomic, and that in many areas it had to be abandoned after farmers and pastoralists had made big capital investments in building homes, fences, and buildings and making other agricultural improvements. From early colonial times continuing until today, Australian land use has gone through many such cycles of land clearance, investment, bankruptcy, and abandonment.

All those economic problems of Australian agriculture, forestry, fisheries, and failed land development are consequences of the low productivity of Australian soils. The other big problem of Australia’s soils is that in many areas they are not only low in nutrients but also high in salt, from three causes. In southwestern Australia’s wheat belt the salt in the ground arises from its having been carried inland over the course of millions of years by sea breezes off the adjacent Indian Ocean. In southeastern Australia, Australia’s other area of most productive farmland rivaling the wheat belt, the basin of Australia’s largest river system, the Murray and Darling Rivers, lies at low elevations and has been repeatedly inundated by the sea and then drained again, leaving much of the salt behind. Still another low-lying basin in Australia’s inland was formerly filled by a freshwater lake that did not drain to the sea, became salty by evaporation (like Utah’s Great Salt Lake and Israel’s and Jordan’s Dead Sea), and eventually dried out, leaving behind salt deposits that became 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. We shall discuss later the consequences of all that salt in the soil: briefly, they include the problem that the salt is easily brought to the surface by land clearance and irrigation agriculture, resulting in salty topsoils in which no crop can grow (Plate 28). Just as Australia’s first farmers, without modern analyses of soil chemistry, could not be aware of the nutrient poverty of Australian soils, they similarly could not be aware of all that salt in the ground. They could no more anticipate the problem of salinization than of nutrient depletion resulting from agriculture.

Whereas the infertility and salinity of Australia’s soils were invisible to the first farmers and are not well known outside Australia among the lay public today, Australia’s water problems are obvious and familiar, such that “desert” is the first association of most people overseas to mention of the Australian environment. That reputation is justified: a disproportionately large fraction of Australia’s area has low rainfall or is extreme desert where agriculture would be impossible without irrigation. Much of Australia’s area remains useless today for any form of agriculture or pastoralism. In those areas where food production is nevertheless possible, the usual pattern is that rainfall is higher near the coast than inland, so that as one proceeds inland one first encounters farmland for growing crops, plus half of Australia’s cattle maintained at high stocking rates; farther inland, sheep stations; still farther inland, cattle stations (the other half of Australia’s cattle, maintained at very low stocking rates), because it remains economic to raise cattle in areas with lower rainfall than sheep; and finally, still farther inland, the desert where there is no food production of any sort.

A more subtle problem with Australia’s rainfall than its low average values is its unpredictability. In many parts of the world supporting agriculture, the season in which rain falls is predictable from year to year: for example, in Southern California