|
|
Soil Degradation
in Australia
Katajura, or the Olgas as they were known
Soil degradation is the term used to describe different ways in which soil is damaged. It is a serious problem in Australia.
One form of soil deradation is wind and another is water erosion.
Other forms of soil degradation have different causes.
Salinity
There is salt in Australia's soil, but mostly it is deep underground and plants are not affected. Underground water in the soil, called the water table, carries dissolved salt. As the water table rises, more and more salt gets dissolved in it. Clearing the land of deep-rooted plants like trees has caused the water table to rise, bringing salt to the surface where it forms a crust on the land. The salt-encrusted land cannot be used for farming, and very few plants will tolerate salty soil. This is called dryland salinity.
In some places, where crops have been heavily irrigated, the excess water has caused the water table to rise, and salinity has resulted.
It is not fully understood how trees help fight salinity, but it is known that planting trees in salt infected areas has reduced salinity. It is thought that trees lower the water tables. Deep rooted plants and crops such as lucerne also help. In areas where the soils will be salty for some time yet, saltbush and other salt tolerant plants have been planted. Sheep can eat saltbush, so the land can be grazed. Some farmers are able to pump their salty ground water into evaporation tanks, and sell the salt.
Other soil degradation problems are where the structure of the soil has become damaged, so that the soil cannot absorb water as well as it did or it becomes lacking in nutrients. 
Poor farming practices can cause this to happen, such
as over grazing, animals making the soil hard and compacted, or
ploughing. Once the nutrients are lacking fertilisers are added,
but over use of these can make the soil acid and therefore poisonous
to plants and water systems.
Land clearing is still happening at a rate faster than replanting. This has an impact on soil degradation and biodiversity loss.
Read some FAQs (frequently asked questions) about Salinity in Australia
If you use any of this information in your own work acknowledge this source in your bibliography like this: Soil Degradation (2007). [Online], Available: www.kidcyber.com.au
updated March 2007