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Publications
Environment Australia, 2001
Salinity means “saltiness”. Just that – too much salt. Soil can become too salty for plants to grow, and in turn the rivers and streams that run through this salty land become salty themselves and pollute areas downstream.
Strangely, for a land as dry as Australia, it all starts with rain. When rain falls on the ground, some evaporates, some ends up in streams and rivers and some is directly absorbed by plants. But some of it also ends up in groundwater – way below the surface, where it moves through tiny holes and gaps in the rocks and the soil.
Some taller trees have roots so deep that they get a lot of the water they need from that groundwater and these trees pump this water into the atmosphere. Groundwater also flows out, often very slowly, through springs, streams and rivers.
But what do you think might happen if too many trees and shrubs have been cleared? Where will the water that soaks into the soil go? It just keeps going down. But what if the groundwater can't flow away fast enough? What might happen to this groundwater?
Well, the groundwater just collects where it is. This means that after a while, there is too much groundwater, so it starts rising towards the surface because there is nowhere else for it to go.
But it isn't just a case of too much water. As the groundwater rises, it also dissolves the salts in the soil, and that salt comes to the surface too. The result? – topsoil that gets saltier and saltier and saltier.
Dead tree in saline billabong, Photo Andrew Tatnell
Do plants like to grow in salty soil? No, they don't! Most plants hate drinking salty water just as much as you would. If they don't have ordinary water, they die.
As the soil gets saltier and saltier, more and more of the plants die. The result? - land that gets barer and barer of vegetation because nothing will grow there.
What happens when all the vegetation dies? What are all the animals that eat this vegetation going to have for dinner? What is going to keep the soil in place when the wind blows and the rain pours down, now that the grass and trees aren't there to keep it where it belongs?
The final result of this frightening process is not just the loss of the trees and grasses, but also loss of the soil itself. There is nothing to keep it there, so it blows and washes away, and with all the salts, so the land downstream also becomes too salty!
What was present in the first drawing that is missing in the second? Live trees and shrubs! Planting more vegetation can stop the salinity process and save the land for the generations to come – generations of farmers and farm animals as well as generations of native plants and animals! And these trees can be good for lots of other reasons - can you think what? But it takes a long time to grow a tree and we have already lost so many trees that replanting them all is an impossible task.
Although it is best to plant trees and shrubs, there are other things, such as pumps and drains, which we can sometimes use to lower groundwater levels.
Think about it! What do you think is the best solution to all this salt?