Erosion is the
transportation of earth materials, particularly soil, and it is a BIG problem
for Australia. Soil erosion is more than 10 times faster than soil formation in
Australia. Our coasts suffer erosion from storms and riverbanks are washed away
after flooding.
Why is
soil erosion such a big deal?
Healthy
soil is vital for growing healthy food. According to Australia’s 2016 State of
the Environment Report, up to 10 million hectares of land has less than 500
years until the topsoil is completely eroded away. Much of this soil is in
fertile growing regions of southern Queensland.
When soil
is washed away it makes streams cloudy so that it is difficult for water plants
to grow and clogs the gills of water animals. Soil being blown away pollutes
the air, making it difficult for animals to breathe and coating the leaves of
plants where it lands.
Topsoil is blown
away in this dust storm on the outskirts of Adelaide (R Merry 1994, CSIRO
Science Image)
Webpage:
- Soil:Formation and erosion(Australia State of the Environment Report 2016)
Farming
for healthy soil
In order to
protect valuable topsoil and keep the land productive, many Australian farmers
have adopted minimal tillage. This means that they leave the stubble of a crop
on the field instead of ploughing the remnants into the soil. Minimal tillage
helps keep water and organic material in the soil, as well as protecting it
from wind and water erosion. New crops are sewn in the stubble of the previous
crop.
Ploughing
the soil helped to control weeds. Now that they don’t plough, farmers use herbicide
to control weeds. Colour-seeking technology can detect green weeds growing
among brown stubble. Herbicide is only applied to the weed, reducing the amount
needed.
Young
cotton plants grow in the stubble of the previous wheat crop (USDA NRCS Texas 2010,
Public domain)
Webpage:
Preventing
erosion in the city
The large
amount of pavement and buildings in cities means there is less soil exposed to
absorb water. After rain, there is a huge amount of runoff that flows into the
stormwater system. Stormwater empties into local streams. After a big rain, the
huge volume of stormwater rushing down the streams carves away at the banks. Some
strategies used to prevent this include paving stormwater drainage areas and
planting trees along streams to help hold the soil together.
Hillsides, construction
sites and places where many people walk are also at a high risk for erosion. Look
around your local area. Can you see places where there is mulch or tree
planting to reduce erosion? Have you ever noticed hay bales around construction
sites? These are all ways of stopping soil from being washed away.
Stormwater has carved away a large portion of
this hillside, exposing tree roots
Explore erosion
at home
Observe erosion
and see if you can prevent it using soil, pans, mulch, plants and a watering
can (check out the video here). Or adapt your experiment to look at the impact of wind too.
Sculpt some sand dunes using sand and straws.
Try out
erosion control using sand, vegetation, a bucket and a watering can.
Investigate an area that has been changed by erosion.