All About Soil

1
All About Soil
All About Soil
4.7A
2

• Soil can basically be separated into 5 main
  parts
• Humus
• Clay
• Silt
• Sand
• 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 aSandy 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
17
(No Transcript)
18

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