A high level of salinity in soil and water can be a cause of serious concern among farmers, restricting agricultural productivity, degrading the natural environment, and having a negative economic impact.
It may cause physiological upset or even death in livestock.
If we are specifically talking about livestock there are a number of things to consider when it comes to the suitability and usability of drinking water, including salinity.
Water source: If you use shallow wells and streams as a source of water it is more likely that they can become contaminated or chemically imbalanced compared to water from larger wells and streams.
Seasonal changes: Seasonal changes can affect water in a number of ways. During hot, dry periods salinity may increase due to evaporation. Livestock also require more water in hot conditions, and the temperature of the water may also increase.
Species: The species of the animal has an affect on how much salinity they can tolerate.
Age and Condition of Livestock: Weak animals along with young and lactating ones are typically more susceptible.
It is therefore always a good idea to regularly check water sources to see if the quality or quantity of water has changed. It would also be wise to take samples to test, as any problems may not be immediately obvious just by appearance.
A good rule of thumb for water salinity, which is measured in electrical conductivity (ECw), is to assume that livestock drinking water 5 dS/m will be satisfactory under almost any circumstances.
5-8 dS/m is generally fine for all livestock, though may cause temporary diarrhoea if not used to such salinity. This level of salinity would be unsuitable for poultry though, decreasing their growth and increasing mortality rates.
8-11 dS/m is completely unfit for poultry. Dairy and beef cattle, swine, horses, and sheep should be okay with this level of salinity.
11-16 dS/m has very limited use and is likely best avoided to be on the safe, Over 15 dS/m should not be used any under circumstances.
Plants and Crops
If we are talking about plants and crops, salinity can have an effect in three ways. Firstly, plants may have stunted growth with reduced yield due to the difficulty to withdraw water from the soil.
Some salts may be directly toxic to plants, damaging the plant internally and affecting its physiological process. The worst-case scenario is death, but reduced growth and leaf burn may also occur.
High amounts of Na and Cl may affect the availability and use of other ions that are paramount to plant growth. These ions may include P, N, Mg or K.
As is the case with different species of livestock, different species of plants have varying tolerances to salinity. These differences may relate to the rate of yield decline and to the salt content of the soil and/or water.
Tolerance may also vary due to different soil types; climatic conditions including light, humidity and temperature; water management practices such as the method of irrigation used, waterlogging as well as the frequency and intensity of these practices; and the stage of growth the plant is in.