Whats the difference between soil and dirt

1
Whats the difference between soil and dirt?
Dirt is what you find under your fingernails.
Soil is what you find under your feet.
2
Think of soil as a thin living skin that covers
the land.
Lets take an elevator ride from the surface to
the bedrock below.
Well pass several distinct layers, or horizons,
as we go.
3
Soil horizon A layer of the soil made of the
same kind of material.
Together, these layers form the soil profile.
Soil profile The horizontal layers (horizons)
in the soil from the surface to the bedrock. Each
layer has a unique history.
4
Ground level

• Plants grow and animals live here.
• A thick cover of plants can keep the soil cool
  and keep it from drying out.

Decomposer An organism that breaks down dead
plant and animal organic matter. Most decomposers
are bacteria and other fungi.
5
Humus The matter left over after all the
nutrients and minerals are gone from dead plant
and animal matter.

• recycle dead plants and animals

6
Topsoil

• Plants grow and animals live on top of the soil.
  
• This is sometimes called the organic layer.
• A thick cover of plants can keep the soil cool
  and keep it from drying out.

7
Subsoil

• This is a mix of mineral particles and some
  humus near the top.
• Subsoil is very low in organic matter compared
  to the topsoil.
• This is the layer where most of the soil's
  nutrients are found.
• Deep plant roots come here looking for water.
• Clays and minerals released up above often stick
  here as water drains down.

8
Organic matter All of the matter in the soil
that first came from living thingsplants,
animals, fungi, and protozoa. It may be fresh or
decomposed.
9
Weathered parent material

• This horizon can be very deep.
• There's no organic matter here at all.
• We're out of reach of all living and dead
  organisms down here.
• It's all rock particles, full of minerals.

10
Parent material The non-living part of all soil
comes from the parent material. It may be broken
off of bedrock underneath. Or a glacier, wind, or
water, can pile up material removed from bedrock
somewhere else.
11
Bedrock

• We finally found solid rock!
• The bedrock formed before the soil above it.
• It will wait here until erosion or an earthquake
  exposes it to the surface.
• Then some of it will be weathered to become the
  next batch of parent material.
• The soil-making process will start all over
  again.

12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)