Why has salinity become such a problem in Australia recently?
What we have done since European settlement is we’ve actually changed profoundly the water balance in the landscape. The vegetation, the woody trees and shrubs and perennial grasses had come to one way of living with the salt. What they have done is they have used all the water possible through evaporation or through runoff and so very little water in the native vegetation moved past the root zone. Now when we came along we tended to take out the deep-rooted trees and shrubs and perennial native grasses and now a great deal more water dribbles past the roots zones of our pastures and our annual crops. To give you some indication of the size of that, in terms of numbers, before we interfered with the system the amount of water that dribbled beneath or leaked beneath the native root system was between half a millimetre and maybe five millimetres a year. Now, under our agricultural system, under our annual crops and annual pastures, that number can be as high as 50 or in some cases even a
