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Soil Salinisation

Salt affected soils cover extensive areas on each continent of the Earth. Salinity, alkalinity and sodicity are among the most important and widespread soil degradation processes and environmental/ecological stresses in the biosphere. They limit agro-ecological potential and represent a considerable ecological and socio-economical risk for sustainable development.

Soil salinisation is a process that leads to an excessive increase of water soluble salts in soil. The salts which accumulate include chlorides, sulphates, carbonates and bicarbonates of sodium, potassium, magnesium and calcium. A distinction can be made between primary and secondary salinisation processes. Primary salinisation involves accumulation of salts through natural processes such as physical or chemical weathering and transport from saline geological deposits or groundwater. Secondary salinisation is caused by human interventions such as inappropriate irrigation practices, use of salt-rich irrigation water and/or poor drainage conditions.

Soil sodification is a process that leads to an accumulation of Na⁺ in the solid and/or liquid phases of the soil as crystallised NaHCO₃ or Na₂CO₃ salts (salt ‘efflorescence’) in highly alkaline soil solution (alkalisation), or as exchangeable Na⁺ ion in the soil absorption complex.