Soil Origin and Development

1. Soil Origin and Development Original by Nancy Williams Modified by Georgia Agricultural Education Curriculum Office July, 2002

2. Soil Body • Terms to know: • Pedon is a section of soil extending from the surface to the depth of the root penetration of the deepest rooted plants. • Polypedon a collection of pedons that are much the same. • Weathering it is where weather, plants are the major agents responsible for forming soil from rock.

3. Soil Body • Physical Weathering- • refers to the effects of such climatic factors as Temperature, water, and wind. One of the most important is frost wedging. • Chemical Weathering- changes the chemical makeup of rock and breaks it down. • Hydrolysis- water reacts with minerals to produce new and softer compounds

4. Rocks and Minerals • Igneous Rock: • it is the basic material of the earth’s crust. It is created by the cooling and solidification of molten materials from deep in the earth. • Sedimentary Rock • Forms when loose materials like mud or sand are deposited by water, wind, and other agents

5. Rocks and Minerals • Metamorphic Rock: • This is where igneous and sedimentary rocks are subjected to great heat and pressure so they change to metamorphic rock.

6. Rocks and Minerals • Sedimentary rock- • Is like limestone or sandstone,formed by deposition of materials in water or by wind. Note: fresh mud and sand that will someday be sedimentary rock. • Igneous rock- • like basalt,formed from molten rock as in volcano. Most of the earth’s crust is igneous rock overlain by sedimentary rock

7. Rocks and Minerals • Metamorphic rock- has been altered by heat, pressure or chemical action. Examples are limestone becomes marble and sandstone becomes quartzite.

8. Rocks and Minerals • What is Residual Soil- • this is soil formed right from bedrock. They are actually less common than soils of parent material carried from elsewhere by wind, water, ice and or gravity. • They form very slowly as the rock must be weathered first.

9. Rocks and Minerals • Glacial Ice- • Carried parent materials all over the northern part of the North America during the four separate periods of glaciations • What is glacial drift? • It is the melting and the shrunk between the glacial periods and transported materials remained in deposits. This is how we got the most beautiful landscapes in the United States.

10. Rocks and Minerals • What is Glacial Till- • It is the melting process where some debris simply dropped in place to form deposits. Eolian is where the wind will carry and leave soil somewhere else. Alluvial Soils- are soils whose parent materials were carried and deposited in moving fresh water to form sediments

11. Rocks and Minerals • Colluvium- • this is where the soil will slide down or roll down a slope. This is scattered in hilly and mountainous areas • Some examples are: Avalanches, mudslides, and landslides.

12. The Soil Profile • Soil does change over time today Scientist have classified them into four areas • They are: • Addition • Losses • Translocations • Transformations

13. The Soil Profile • What is Additions? • It is materials such as fallen leaves windblown dust or chemicals from air pollution may be added to the soil

14. The Soil Profile • What is Losses? • It is materials that may be lost from the soil as a result of deep leaching or erosion from the surface.

15. The Soil Profile • What is Translocation? • It is materials that may be moved within the soil as with leaching deeper into the soil or being carried upward with evaporating water.

16. The Soil Profile • What is Transformation? • It is the materials that may be altered in the soil, for example organic matter decay weathering of the minerals to smaller particles or chemical reactions.

17. The Soil Profile • Each of these processes will occur at different depths of the soil. • For example: • Organic Matter will be at the top or the near the surface of the soil.

18. The Soil Profile • What is a horizon? • They are the layers of the different types of soil and the different depths that the layers will be located at.

19. The Soil Profile • What is a soil profile? • It is the vertical section through the soil and extending into the unwreathered parent materials and exposing all the horizons.

20. Master Horizons • What is the Master Horizons? • The are A, B and C horizons are known as the master horizons. They are a part of a system for naming soil horizons in which each layer is identified by a code O, A, E, B, C and R

21. Horizons • The O Horizon- • Is the organic layer made of wholly or partially decayed plant material and animal debris . You can normally find this layer in a forest with fallen leaves, branches and other debris.

22. Horizons • The A Horizon- • It is usually called the topsoil by most farmers. This is where the organic matter accumulates over time. This layer is very prone to leaching and losing iron and other minerals. The A horizon provides the best environment for the growth of plant roots, microorganisms and other life.

23. Horizons • The E Horizon- • This is the zone of the greatest leaching of clay, chemicals and organic matter.

24. Horizons • The B Horizon- • This is also called the subsoil is often called the zone of accumulation where chemicals leached out of the A horizon

25. Horizons • The C Horizon- • lacks the properties of the A and B horizon. It is the soil layer that is less touched by soil forming processes and is usually the parent material soil

26. Horizons • The R Horizon- • Is the underlying bedrock such as the limestone, sandstone, and or granite.