all types of soils and soil formation

1. SOILSSOILS

4. Soil: Definition
Engineering definition:
Anything that can be
removed without blasting
Solid earth material that has been altered by
physical, chemical and organic processes so
that it can support rooted plant life.

5. Soil Production

6. Conversion of rock to soil
Soil Production: Inputs

7. Soil Production: Outputs
Downslope movement of soil

8. Factors of Soil Formation
• Climate
• Organisms
• Parental Material
• Topography
• Time

9. Climate
• Temperature and precipitation
• Indirect controls (e.g., types of plants)
• Weathering rates
The greater the rainfall, the faster the rates
of erosion and leaching.
Factors of Soil Formation

10. Organisms
• Types of native vegetation
• Weathering is dependent of plant growth
• Plant and animal activity produces humic
acids that are powerful weathering agents.
• Plants can physically erode as well as
chemically erode.
• Plants stabilize soil profiles, Animals
(including humans) tend to increase erosion.
Factors of Soil Formation

11. Parental Material:
• Chemistry
• Mineralogy
• Grain size
Factors of Soil Formation

12. Soil Texture

13. Topography:
• Ground slope
• Elevation
• Aspect (e.g., north facing vs. south facing slopes)
Factors of Soil Formation

14. Downslope transport of soil is a function
of slope:
The steeper the surface slope, the more
likely any eroded material is to be
transported out of the system.
Factors of Soil Formation

15. Soils on hillslopes reach an equilibrium
thickness, often about 1 m.
Soils on flat surfaces, such as floodplains
or plateaus, tend to thicken through time
due to weathering rates being greater than
sediment transport rates.
Factors of Soil Formation

16. Time
• Development and destruction of
soil horizons
• Reaction rates are slow, the
longer a rock unit has been
exposed, the more likely it is to be
weathered.
Factors of Soil Formation

17. Soil Development

18. Decomposition of organic matter
Humification to form complex organic matter
Weathering of rocks to produce more stable
forms
Physical weathering
 Fragmentation of rock
Freeze-thaw; drying-wetting; fire
 Physical abrasion
Abrasion by glaciers
Chemical weathering
 Dissolves primary minerals
 Forms secondary minerals
Transformations

19. Saprolite is weathered rock that retains
remnant rock structure.
Saprolite
Soil
Bedrock

20. Weathering Products:
Product of weathering is
regolith or soil
Regolith or soil that is
transported is called
sediment

21. Weathering often
proceeds along
fractures and
joints, resulting in
progressive
development of
corestones.

22. Weathering often proceeds
along fractures and joints,
resulting in progressive
development of corestones
that when exposed at the
surface can form tors and
larger bornhardts (also
known as inselbergs or rock
islands).

23. Inselberg (bornhardt), Mali

24. Inselberg (bornhardt), Ayers Rock, Australia

25. Inselberg (bornhardt), precambrian granite, central Texas

26. Typical
soil
profile

27. Cookport soil,
Pennsylvania
C Horizon
B Horizon
A Horizon

28. Laterites

29. Deforestation removes the fertile organic layer. The underlying soil is
infertile, dries to brick-like hardness when it dries out, and is difficult to
cultivate. Aluminum (from bauxite) and iron (from limonite) can be mined
from these soils.
DEFORESTATION

30. Carajas, Brazil

31. Limits of Soil Development
Balance Between:
Downward Lowering of Surface
Downward Migration of Horizons
If erosion rapid or soil evolution slow, soils may
never mature beyond a certain point.
Extremely ancient soils may have lost
everything movable

32. Weathering with Climate
Polar Temperate TropicalArid

33. Soil Production Function

34. Sugar Loaf, Rio De Janiero, Brazil

35. Convex, soil-mantled hillslopes, Northern California

36. Agricultural Soil Loss
Erosion of unprotected soils during periods
where they remain fallow and without
vegetative cover leads to increased erosion

37. Samples of
different types of
soil

38. Alluvial soil
The most fertile
soil found in the
northern plains of
India

39. Black soil
Also known as Regur
soil found in peninsular
India

40. Red soil
Rich in Iron Suitable for wheat
and rice

41. We know more about the movement of
celestial bodies than about the soil underfoot.
- Leonardo da Vinci

42. Done by
Snehal
Sneharsh
Yogaksh
Prallam
Deep
Rudresh
