1. 1. Soil as a Natural Resource

2. Learning Outcome
At the end of this section the students will be able to define soil and identify the major components of a soil

3. Natural Resources
Living – Animals and Plants (Renewable, Non Renewable)
Non Living –
Perpetual : Solar Energy, Wind, Tide, Flowing Water
Renewable : Fresh air, Soil, Fresh Water
Non Renewable : Fossil Fuels, Metallic Minerals, Non-metallic minerals
Perpetual = Permanent, Everlasting, long-lasting

4. Soils as a Natural Resource
What is a soil?
“The thin layer of soil covering the Earth’s surface represents the difference between survival and extinction of most terrestrial life”

5. Soil Medium for plant growth – food production
Without soil, terrestrial ecosystems would not exist
Forms relatively a thin mantle over the earth
Early civilizations – Nile, Tigris, Euphrates, Indus, Yangtze, Hwang Ho – fertile soils
Civilizations declined due to decline and misuse of land and soil

6. Soils Crucial to land use planning Waste disposal
Evaluation of natural hazards
Flooding
Landslides
Earthquakes
Evaluation building construction

7. A renewable resource
Man’s actions made it very fragile – highly susceptible to damage and misuse
Takes hundreds to thousands of years to develop few centimeters of soil
If not managed properly, it will become a non-renewable resource

8. Soils defined
Natural body that occurs on the land surface, occupies space, and is characterized by one or both of the following:
Horizons or layers
Upper limit is air or shallow water (less than 2.5 m) and Lower limit is either bedrock or the limit of biological activity (usually set at 2 m)

9. Soil Definition Soil Scientist:
Solid earth material that can support rooted plant life
Unconsolidated mineral matter on the surface of the earth that has been subjected to and influenced by genetic and environmental factors of: parent material, climate (moisture and temperature), macro and micro organisms, and topography, all acting over a period of time and producing a product soil that differs from the material from which it is derived in many physical chemical and biological properties and characteristics (SSSA)

10. Non Soil Areas Beaches Active pits Urban Lands Deep water habitats
Bed rock
Areas that do not support plant growth are not considered soil but are mapped as miscellaneous areas in soil survey reports.

11. Soil Components Soils consist of four major components:
(1) mineral (or inorganic),
(2) organic,
(3) water, and
(4) air.
Relative proportions vary with soil type and climatic conditions.