Soil

1
Soil

• Its Ecosystem
• Chapter 8

2
Objectives

• Understand basic properties of soil and their
  characteristics
• Describe a typical soil profile.
• What are the 4 common soil groups.
• Why is soil degradation so important?
• Describe problems that develop from poor
  management.

3
What is soil?

• A complex natural material derived from
  disintegrated and decomposed rocks and organic
  materials, which provides nutrients, moisture and
  anchorage for land plants.

4
Four Principal components of soil.

• 1. Mineral
• 2. Air
• 3. Water
• 4.Organic Material

5
How soil are formed

• 1- Parent material, material from which soils
  were formed.
• 2- Climate, temperature and moisture.
• 3- Living organisms, microscopic and macroscopic
  plants and animals.
• 4- Topography, shape and position of land
  surfaces.
• 5- Time, period during which parent materials
  have been subjected to soil formation.

6
Plants and Soil

• Nutrients are released by decomposers
• Productive soil is a dynamic process
• Nutrient cycling is key to understanding

7
Soil characteristics

• Soil Profile
• Organized into horizons
• O-Organic
• A-Topsoil
• B-Subsoil
• C-Parent material

8
(No Transcript)
9
Soil Texture

• Clay is the smallest
• Silt
• Sand the largest
• Loam a mixture

10
(No Transcript)
11
Soil Structure 4 types of aggregates.

• 1. Granular (organic matter content is high)
• 2. Prismatic (found in subsoils and common in
  arid semiarid regions)
• 3. Blocky (most common in subsoils, particularly
  those in humid regions)
• 4. Platy (can occur in any part of the profile)

12
Soil Classes

• Mollisols-Very fertile dark soild found in
  temperate grassland biomes. Deep A horizon.
• Oxisols-Soils of the tropical and subtropics
  regions. Have thin layer of iron and Al oxides
  in B horizons. Limited fertility.

13
Soil Classes

• Alfisols-Widespread weathered forest soils. Not
  deep they have well developed O,A,B,C can be
  farmed.
• Aridisols-found in drylands and deserts, lack
  vegetation and precipitation. Thin light
  colored. Can lead to salinization due to high
  evaporation rates.

14
Soil Plants

• Nutrient-Holding Capacity
• Water Holding Capacity (permeability)
• Aeration ( porosity)
• pH

15
Soil as an Ecosystem

• Soil organisms support food web
• Residue from decomposition is Humus
• Structure arrangement
• Plants protect topsoil, roots support structure

16
(No Transcript)
17
Soil Degradation
18
(No Transcript)
19
Erosion and Desertification

• Splash
• Sheet
• Gully
• Wind
• Desert pavement

20
Causing and Correcting Erosion

• Over cultivation
• Overgrazing
• Deforestation
• Sedimentation

21
Addressing Soil Degradation

• SAREP
• LISA
• BIOS
• BIFFS