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9.4 Caring for the country: 2. Soil as a resource
| Syllabus reference (October 2002 version) | ||
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2. Soil as a resource that requires careful management. |
Students learn to:
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Students: |
Extract from Earth and Environmental Science
Stage 6 Syllabus (Amended October 2002). © Board of Studies, NSW
[Edit: 24 Jul 08]
Prior learning: Preliminary module 8.3 (subsections 2 and 5)
Background: Australia’s soils have taken a long time to form and are quite fragile. Our natural flora and fauna have evolved with the soil, resulting in flora that cope well on low nutrient soils and fauna that does minimal damage to the soil due to their soft feet and generally small size. The Australian Aborigines managed the soil for up to 60 000 years. They didn’t clear land as European settlers did so didn’t have the erosion problems that occurred later.
plan and perform a series of investigations to determine the effect of compaction or tracking on a soil
Plan how to do this investigation by brainstorming in a group. Below are two ideas that you could use to perform the investigation.
Idea one:
- Each group obtain a sample of soil. Consider using
soils of the local area. You might use sandy soil, loamy soil, or clay
soil, or a mixture such as sandy loam. If there are different soils types
available, each group could use a different soil type so that comparisons
can be made.
- Test your soil for properties such as: ability
to hold water; ability to hold together (friability); aeration (amount
of air in the soil).
Down to earth: soil testing
LMP, NSW Department of Education and Training.
Click on soil testing then click on whichever test you want to investigate.
- Compact the soil. This could be done by using a
hammer or crow bar to pack soil into an appropriate container, such as
a tin can.
- Retest the soil for the same properties above.
Idea two:
- Find two or three sites in your area that show
different degrees of compaction. Some examples might be a driveway, a
footpath, an oval and a garden.
- Cut the two ends out of an empty tin can and place
it firmly over the soil of a sample site.
- Measure 500 mL of water and pour this into the
can.
- Start timing immediately and record the amount
of time the water takes to enter the soil.
- Repeat this procedure for each soil sample site.
Perform your investigation and make conclusions about the effect of compaction of different soil types.
gather information from first-hand or secondary sources to evaluate a program or strategy used in NSW to treat soil erosion
If you live in a rural area where there has been a problem of soil erosion, you could gather first-hand information and evaluate a strategy that has occurred locally. If you live in an urban area look at soil erosion around building sites. Identify where the erosion has occurred and identify if it has been remedied. If there is a sign telling you who the authority is that has run the program, contact them to obtain details. If there is no sign, go to the local council and ask them for contact details for the organisation involved. It may have been a local land care group or the NSW Department of Land and Water Conservation. Consider what information you could gather. Ask questions such as:
- What appears to have caused the soil erosion?
- Was it mostly natural or caused by human intervention?
- Has the local community been consulted or involved in the repair work?
- Has the solution been successful?
- Has the local Aboriginal community been consulted to take advantage of its long connection with the land?
To gather secondary information, go to sources in the library, such as journals, CD–ROMs or the Internet. It would be best to use Australian sites as our soils are different from most other soils, particularly those in the northern hemisphere. You may want to talk to NSW Agriculture, the NSW Department of Land and Water Conservation or contractors who do soil conservation work. Prepare your questions carefully before making a time to talk to them.
Evaluate the program you have studied by deciding how effective it has been. There may be an evaluation with the program or you may need to check yourself to see how successful it has been. Some criteria you could use are:
- Is there continued soil erosion or has it since appeared near the original site?
- Is it impossible to identify where the erosion used to be?
outline a cause of soil erosion in NSW due to:
- an agricultural process
- urbanisation
and identify a management strategy that prevents or reduces these causes of soil erosion.
Agricultural process
There are many potential causes of soil erosion in agriculture, but one simple example is overcultivation. Overcultivation means that the soil is disturbed by ploughing it too often and to too great a depth, thus leaving it exposed for long periods of time and susceptible to erosion by wind and water. A management strategy that prevents this type of soil erosion is minimum tillage or conservation tillage. Minimum tillage involves the planting of the next crop into the stubble of the previous crop using specially designed seed drills that create minimum disturbance to the soil structure and the protective cover of stubble from the previous crop.
Urbanisation
Siltation of many lakes, such as Lake Macquarie near Newcastle is accelerated due to soil erosion from housing estate developments entering the stormwater drains. To prevent soil reaching the lake, traps are built to catch the silt. Most councils make it compulsory for all building sites to have silt traps to prevent soil washing away from the sites. Contact your local council to find out what their regulations are for building sites to minimise silt flow into creeks, rivers and lakes.
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