Salt of the Earth – Salinity
The presence of soluble salts in soil and water is known as salinity. These salts occur naturally, resulting from the weathering of the earth’s crust. Throughout the earth’s history, this weathering has resulted in the deposition of salts throughout the landscape. The distribution of these salts is not even, with many areas being more saline than others. Below are answers to some frequently asked questions about salinity.
What does salinity mean to me?
Well that depends on who you are. Soluble salts are present in all waters and have a direct impact on plant growth, both in the short and long term. If you’re a farmer, gardener, landscaper or responsible for the ongoing management of plant growth, salinity in soil and water will directly affect the health of your plants.
If you’re a construction manager, builder or responsible for maintaining or upgrading facilities, salinity in soils poses significant risks to the structural integrity of buildings, roads and other infrastructure. It also plays a huge role in the stability of the soil on which you plan to develop.
How does salinity affect buildings?
The salts present in saline soils have the potential to move into concrete, brick and other construction materials via capillary action. The crystallisation of the salt has the potential to severely damage construction materials, which can potentially compromise essential components of some structures (such as footings and foundations). Additionally, saline soils provide the electrolyte required for corrosion of concrete, steel and other construction materials within a structure. Decreased resistivity of a soil renders infrastructure within it more susceptible to corrosion.
How does salinity affect soil stability?
Soils are much more complex than their appearance would suggest. Their physical properties can be affected by a complex relationship of soluble and exchangeable cations and anions. When sodium makes up a significant portion of the exchangeable cations in a soil, the soil’s structure is typically more susceptible to collapse when exposed to water. This can result in weathering and erosion, which can be detrimental to a landscape, river or infrastructure.
Can saline waters be used for irrigation?
In certain instances, yes.
Generally speaking, strict irrigation regimes must be followed and careful monitoring is essential for a successful outcome. SESL Australia’s team has been involved in some very successful projects that utilised saline waters for irrigation. A common example of this is irrigation of waters from wastewater treatment plants, which typically contain elevated salts. This scenario usually requires modelling to ensure that irrigation is delivered effectively.
SESL Australia has a team of experienced consultants, including environmental consultants servicing the construction industry, agricultural consultants, urban horticultural consultants and hydrogeology specialists. The diverse nature of our team means that we can assist on any number of issues or potential issues arising from salinity. We encourage you to give our friendly staff a call today to find out how we can help you.