Adverse Effects of Salt on Soil

Soil Salinity

• All soils have some degree of water-soluble salts, but soils with a high concentration of salt are considered saline. Soils receive their salt content from water sources below that make their way up into soil, from irrigation water or fertilizers or from the breakdown of minerals in the soil. In non-saline soils, these salts are typically leached out by rain water or other natural occurrences. But in those climates where salt is not effectively leached out (deserts, for instance), salt can remain in soil where it can inhibit plant growth.

Effects on Plant Growth

• Salt primarily affects the way plants absorb moisture from soil. In excessively saline soils, it takes more energy for the plant to absorb the same amount of water than moisture uptake would require in non-saline soils. Because the energy the plant uses to absorb the water is diverted away from building new growth on the plant, soil salinity often becomes apparent as stunted new growth, leaf wilting and similar symptoms. Biologists call this process, whereby plants expend more energy to extract the same amount of moisture from soil, the osmotic effect.

Other Effects

• The osmotic effect can be observed in any plants growing in any saline soils, but there are other, less general effects of soil salinity as well. Plants that have a particular sensitivity to elements such as sodium, chlorine and boron can suffer a toxic reaction in saline soils. Salts in soil also regulate nutrition levels in plants, so a saline soil can interfere with a plant's nutrient balance and harm plant health.

Adjusting Soil Salinity

• Salts are usually removed from soil by drainage, so irrigation can remove salt from an excessively saline soil. However, if a soil has a high concentration of salt to begin with, chances are good that soil drainage will not be sufficient enough to remove the salt. If your plants repeatedly suffer from the ill effects of soil salinity, have the soil tested by a local university extension office to determine the source of the salt and advice on how to improve the soil's fertility.