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.
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.
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.
