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Water is taken up by the fine roots of plants through the process of osmosis, which involves the movement of water from regions of low salt concentration (such as the soil) to regions of high salt concentration (such as the inside of root cells). When salt concentrations in the soil are high, the movement of water from the soil to the root is slowed down. When the salt concentrations in the soil are higher than inside the root cells, the soil will draw water from the root, and the plant will wilt and die. This is the basic way in which salinization affects plant production.
The damaging effects of salt on plants are caused not only by osmotic forces, but also by toxic levels of sodium and chloride.
Fruit crops and woody ornamentals are especially sensitive to high levels of these elements.
Also, the high pH value (a measure of the acid/alkaline balance) caused by excess sodium may result in micronutrient deficiencies.

Plants vary in their sensitivity to salt. Those with the lowest salt tolerance include tomatoes, onions and lettuce. At the other extreme are halophytes, which occur most frequently in salt marshes, beaches and other saline environments.
Soil salinization is a common problem in areas with low rainfall. When combined with irrigation and poor drainage it can lead to permanent soil fertility loss. This type of salinity is a common factor of many drought-induced humanitarian crises.

Soil salinization as a feature of rapid-onset disasters is however limited exclusively to tsunamis. Because of this, FAO is aware that many humanitarian organizations working in Aceh may not have previously encountered the phenomenon, and there may be a lack of accessible information on identifying and dealing with salt-affected soils.

Fortunately, Aceh Province is endowed with abundant rainfall, which is not common in most areas with soil salinity problems. While the land rehabilitation efforts should make the most of this advantage, other conventional treatments, e.g. appropriate drainage, deep rooting crops, gypsums, might be introduced when and where appropriate.

Download: FAO Field guide: The impact of salt water on agricultural land in Aceh Province.

 contact: tsunami@fao.org © FAO, 2005