Society for Experimental Biology Annual Main Meeting

Salinisation is the accumulation of water-soluble salts in the soil solum or regolith to a level that impacts on agricultural production, environmental health and economic welfare. Salt-affected soils occur in more than a hundred countries of the world with a variety of extents, nature and properties. No climatic zone in the world is free from salinisation, although the general perception is focussed on arid and semiarid regions. Salinisation is a complex process involving seasonal dynamics of salts, water movement in a soil profile and hydrological interactions of groundwater. While rainfall, aeolian deposits, mineral weathering and stored salts are the sources of salts, surface and ground waters can redistribute the accumulated salts. Sodium salts dominate in many saline soils of the world. But salts of other cations such as calcium, magnesium and iron are also found in specific locations. Different types of salinisation with a prevalence of sodium salts affect about 30% of the land area in Australia. While more attention is given to groundwater associated salinity and irrigation salinity, which affect about 16% of the agricultural area, recent investigations suggest that 67% of the agricultural area has a potential for Ftransient salinity_, a type of non-groundwater associated salinity. Agricultural soils in Australia, being predominantly sodic, accumulate salts under seasonal fluctuations and have multiple subsoil constraints such as alkalinity, acidity, sodicity and toxic ions. This paper also examines soil processes that dictate the exact edaphic environment upon which root functions depend and can help in research on plant improvement.