Soil

1. All All About
About
Soil
Soil
4.7A

2. Soil can basically be separated
into 5 main parts:
1. Humus
2. Clay
3. Silt
4. Sand
5. Gravel

3. Humus: A dark, moist soil composed of bits of
dead, rotting insects, animals, leaves, roots, sticks,
and food. Humus adds nutrients to the soil which
plants need to grow and live.

4. Clay: A soil that holds water. When wet, clay feels
slippery and slimy. It is made of particles that are
smaller than 0.004 millimeters.

5. Silt: Soil that looks like fine grains or tiny pieces of
rock. Particles classified as silt measure from
0.004 millimeters to 0.006 millimeters.

6. Sand: Soil that is coarse and drains quickly. Sand
particles measure from about 0.006 millimeters to
2.00 millimeters.

7. Gravel: Visible rock particles, sometimes referred
to as pebbles.

8. Soil Profiles
• A soil profile is a view of
a cross section of soil.
• Most living material
exists in the top section,
or topsoil.
• Plant roots often extend
into the second layer,
called the subsoil.
• The bottom two layers
consist mostly of rock.

9. Characteristics of Soil Horizons
• 0 Horizon-located on surface, mostly O.M. (organic materials)
• A Horizon-Called Topsoil, good amounts of O.M. and minerals.
• B Horizon- Known as Subsoil, Less O.M.
• C Horizon- Mostly parent material, does little for plant growth.

10. Soil Texture
Soil texture is the
relative sizes of the
different soil particles.

11. Major Soil Texture Classes
• Sand is the largest particle.
• Silt is a medium-sized
particle.
• Clay is the smallest particle
in size.

12. Characteristics of a
Sandy Soil

13. Characteristics of a
Silty Soil

14. Characteristics of a Clay Soil

15. Soil Structure
• Sand, silt and clay
particles combine with
one anther to form
cluster called
aggregates.
• The way in which
aggregates or clusters
are arranged is
referred to as soil
structure.

16. Soil Structure Categories

18. Modified from a presentation by Carrie
Nagle, Mecklenberg Public Schools.