Soil Flashcards
Define soil
A mixture of air, water, broken down rock and organic material taking thousands of years to form.
Renewable or non - renewable
Non renewable
How is soil formed
From the gradual breaking down and weathering of rock.
How are rocks weathered
Sun
Wind
Ice
Chemical changes
Water - dissolves minerals found in rocks, reacting and forming new minerals which break down the rock.
Oxygen - combined with minerals can weather the rock
The acid of rain
Rocks rubbing up against each other in a stream or river.
What happens to the minerals of rocks when breaking down
Minerals become available to plants
Seeds from weathered rocks are able to germinate and send roots into new soil
As plants die and leaves fall onto the soil they decompose and add to the soil fertility
Define Horizons
Layers of soil
What do Horizons do
Determine how to best farm different areas and how and when to treat soil.
How are horizons layered
Using letters so they are easily identified and compared
From top to bottom: O (Organic matter), A, B, C, and Rock
Does all soil have all horizons
No, some soils may have all horizons - others may have only one or two
3 characteristics that describe Australian Soil
Less fertile - The constant weathering has washed away many of the nutrients and minerals creating poor soil
Saltier- The continent was once covered by ocean but when receded the salt minerals remained
Clay composition - Much of soil is composed of clay which restricts water drainage and creates difficulty for the roots of plants to penetrate
Define penetration
where the water cannot absorb into the roots of plants
Solutions to these issues
- Adding nutrients and chemicals to soil
- Regularly testing soil
- Adding fertilizer containing the chemicals the plants require - as crops grow these nutrients are drawn from the soil and farmers continue to replace them (annually)
