|It takes a really long time to form topsoil, so we need to protect
and conserve soil. A
rule of thumb is that it takes a hundred years to form one inch of
topsoil. A thousand years!
Remember, just as we need good soil today, so will people in the years to
||When the ground is left bare
like this, soil could be blown away by the wind, or carried away by water.
This is called erosion, and we need to prevent it from happening. A
lot of soil erosion happened in the 1930ísóso much soil was blowing
around in the air that it became known as the Dust Bowl.
|Do you see how the top layer
almost looks like a crust on top of the soil profile?
That is because this soil has been plowed, and the structure of the
soil has been destroyed.
|Letís look below the plow layer.
See how this horizon is all cracked?
It looks like a whole bunch of blocks stacked together.
Letís remove some of these blocks and take a closer look at them.
|Here are some more of those blocks.
They still hold together when you pull them out of the profile.
Soil structure is the arrangement of smaller soil particles to form
larger pieces, such as these blocks.
It is important to have good soil structure.
Remember how the A horizon had a thick crust on top of it?
|| That is a bad thing, because soils need cracks and holes, or pores.
Why does soil need pores? Because
the pores are where water is stored, and without soil structure and pores,
water has a hard time getting down into the soil profile and to plant
||A worm has been through here.
How do I know? You can see the tracks (look at the tip of the pencil)!
The soil is home for many animals and microorganisms.
Can you think of some other animals that live in the soil?
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