Definition – What does Saline Soil Mean?
Saline soils – soil that contain excess soluble salts in the root zone.
Where is saline soil found
Saline, or salty, soils are found in a number of different regions, particularly those in arid and semiarid climates without enough rainfall to leach the salts through the soil. In desert areas, irrigation water itself may be high in salts.
Saline soils are also common near the ocean where strong onshore winds carry salty spray inland and deposit it on gardens, where it creates problems for plant roots and foliage. Salt spray on plant foliage makes leaves look as though they’re scorched or burned. In extreme cases, it can even kill the plant. In diagnosing the problems of ailing plants in these areas, it’s always wise to think about the possibilities of salt contamination.
Soils adjacent to walkways and roadways that are salted in winter to prevent icing often receive enough salts to damage plants. Storm drainage systems can carry this salty water into gardens a considerable distance from the original site.
Soluble salts in the soil that cause trouble for gardeners include common table salt (sodium chloride) as well as salts of potassium, magnesium, and calcium. Those soil salts are the product of the weathering of soil minerals and the residue left on soil surfaces when water evaporates. Water carries dissolved salts from subsoils as it moves upward through the soil. If the water evaporates from the surface, the salts are deposited in the soil there.
One indication of saline soils is a white or black crust of salt on the soil surface. Salts not carried away by rain or irrigation can accumulate enough to cause serious plant damage. This situation often occurs in areas with poor drainage.
Saline soils may also be sodic, extremely alkaline with a high concentration of free sodium. Sodium ruins soil structure and makes the soil impermeable to water. It may form caustic soda (sodium hydroxide), which dissolves organic matter.
Water is one of the management tools for saline soils, so gardening in areas with low average rainfall can be a challenge.
Causes of soil salinity
- High salt content in the parent material of the soil and low rainfall leading to low leaching of salts from the soil.
- High salt content in parent rock of soil and high rainfall (or over irrigation) with poor internal drainage leading to low percolation and much accumulation of salts on the surface.
- Over use of ground water for surface irrigation. ( Ground water contains more salt content than surface fresh water).
- Growing water intensive crops in dry areas( high PET- Potential EvapoTranspiration) where plants absorb ground water through capillary action from their roots to surface leaving behind salts to accumulate.
- Application of high dosage of chemical fertilisers.
How to prevent soil salinization
- Improving internal drainage and soil washing.
- Using Magnetised water for irrigation, it improves filtration and dissolving properties of water.
- Sodic soils can be treated with addition of gypsum.
- Soil relaying, it is costly, less effective and leads to soil loss elsewhere.
- Following agro-climatic guidelines, growing crops suitable to the local geology, pedology, climatic and economic conditions.
- Effective irrigation practices and rationing the use of ground water.
- Using organic fertilizers in hand with chemical ones.
- Growing salt resistant grass like cynadon which can act as fodder.
- Developing saline resistant crop varieties with genetic engineering.
Methods of removing salt from soil
Soil salinity can be reduced through good drainage that will allow salts to be washed out of the soil. While adding certain amendments to the soil will not by itself reduce or clear up soil salinity problems, amendments can help with the soil’s drainage and in turn, leads to helping to reversing soil salinity.
Using water from a well, water softener or the irrigation runoff water from local fields can do a lot to add salts to the soil. If your well water is used for drinking, then it should be just fine to use on your garden areas.
Gardening in Arid Regions
In arid regions of the United States, such as the Southwest, which is noted for salty alkaline soils, gardening is far easier if plant choices are limited to natives. It’s usually too difficult to correct and maintain large areas of saline soils because of the amount of water required to leach salts from the soil. Plants not constituted to tolerate salt can be grown in raised beds or containers with prepared or commercial soil mixes. Read more from How to Improve and Manage Soils of Arid Climates
Gardening by the Sea
Oceanside gardens can be somewhat protected from salt spray borne onshore by wind by placing them on the inland side of sheltering structures. Fences and wind screens also provide some protection from salt-laden breezes. Once again, the choice of salt-tolerant plants makes gardening far easier.
Plants in the path of runoff from areas treated with salt during the winter often have their roots in salt-affected soils at the same time that their foliage is being sprayed with salty water from passing vehicles.