In Australia, soil salinity is an enormous problem. At this time, it would appear that the worst affected areas relate to those areas with winter dominant rainfall.
Less severely affected areas are now being recognised in more uniform rainfall zones (that is, neither summer nor winter dominant), whilst some salinisation is evident in summer dominant rainfall zones, for instance Liverpool Plains.
This distribution also reflects the spread over time of the problem in Australia, with the highly winter dominant areas being those to first show signs of salinisation, and the summer dominant zones being the last to show salinisation.
Dryland salinity (on non-irrigated land) occurs when the concentration of soluble salts near the soil surface is sufficient to reduce plant growth.
In Western Australia, this is basically a water management problem: Increased recharge raises the watertable, bringing naturally stored salts from depth to the surface.
Problems that develop from surface salinity include loss of agricultural productivity, loss of natural biodiversity, damage to buildings, roads and other structures, and degradation of water supplies.
Salinity, which has developed by changing land use and management, is called secondary salinity. It is caused by a change in the water balance, leading to more water in the soil and a rising watertable. This mobilises stored salts, which rise with the watertable towards the surface. Clearing for agriculture has been the major cause of secondary salinity in Australia.
