Some Notes on Saline Soils
- Most crops are more sensitive to soil salinity in hot, dry conditions than in cool,
humid conditions. - Choosing to grow salt tolerant species and varieties may be the simplest solution;
- Plants growing in poor, infertile soils may appear to be more salt tolerant than
plants growing in fertile soils. In these cases it is the soil fertility and not the soil
salinity which is the more important factor limiting plant growth. - As more and more water is lost from the soil, by drainage, evaporation and
transpiration, the soil moisture becomes more and more concentrated with salts. As
a result, plants experience increased salt stress as well as water stress when the soil
dries out. - Crops are generally more sensitive when they are seedlings than when they are
mature plants. This is partly explained by the fact that soils are normally more
saline in the upper horizon, where the young seedling roots grow, than lower down
in the soil. - The level of soil salinity is constantly changing, due to changes in rainfall and/or
irrigation, temperature and wind. Farmers who understand how and when these
changes occur can sometimes produce crops on saline soils where others would fail.
What Can be Done about Saline Soils?
- Irrigate, applying extra water to leach (flush out) the salts.
- Install an underdrainage system to remove the saline drainage water away from the
roots. - Add hydrated calcium sulphate (Gypsum); this replaces the sodium in the soil,
reduces the alkalinity and balances the salts in the soil. - Add powdered sulphur; this makes sodium and chlorine more soluble, and allows
other elements such as calcium and magnesium to replace them.
Salt Tolerance of Plants
Crops differ in the degree to which they are affected by soil salinity; some species such
as barley can produce a reasonable yield in highly saline soils up to 18 dS/m, while
others such as beans and carrots grow very poorly in soils with only 5 dS/m.
In general, plants with low drought tolerance also have low saline tolerance.
Tolerant
Barley Hordeum vulgare Jojoba Simmondsia chinensis
Bermuda Grass Cynodon dactylon Leucaena Leucaena leucocephala
Cotton Gossypium hirsutum Saltbush Atriplex spp.
Date Palm Phoenix dactylifera Silt Grass Paspalum vaginatum
Durum Wheat Triticum turgidum Sugar beet etc Beta vulgaris
Guayule Parthenium argentatum Triticale Triticosecale
Grow salt tolerant crops—see list below.