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The Origin of Soil and Its Properties
Andrew Hammermeister
Organic Agriculture Centre of Canada
Dalhousie University, Faculty of Agriculture

2. How can I live my life stepping on this
stuff and not wonder at all?
William Bryant

3. “Probably more harm has been done to soil
science by the almost universal attempts to look
upon the soil merely as a producer of crops
rather than as a natural body worth in and for
itself of all the study that can be devoted to it,
than most men realize.”
--- C. F. Marbut, 1920

4. A Rainbow of Soil
A rainbow of soil is under our feet;
Red as a barn and black as a peat.
It’s yellow as lemon and white as the
snow;
Bluish gray. So many colors below.
Hidden in darkness as thick as the
night;
The only rainbow that can form
without light.
Dig you a pit, or bore you a hole,
you’ll find enough colors to well rest
your soul.
F.D. Hole, 1985

5. Soil is any naturally-occurring, unconsolidated
(loose) material on the surface of the earth,
which will support plant growth.

6. Soil
• Basic resource sustaining all terrestrial
ecosystems.
• Soils are not a renewable resource in the scale of
human lifetimes.
• Most soil profiles are thousand of years in the
making
• In some regions of the world, human activities
are destroying some soils faster than nature can
rebuild/restore them

7. Soil performs 3 main functions:
1. Provide a medium for plant growth
2. Regulate and partition water flow through the
environment
3. Serve as an environmental buffer
a.
Can hold nutrients and release them as required by plants
b.
Can also breakdown harmful compounds into substances that
are not toxic to plants and animals (limited ability).

8. Soil is a product of:
Parent material
Climate
Topography
Biology
Time
Humans!

11. Influence of Parent (geological) Material
Glacial deposition
(Photo K.Murray)
Glacial Action
(Photo J.C.Miller)
Soil formed on Glacial "Till"
(Photo Dr.J.A.Robertson)

12. Fluvial materials – sorted by water

13. Aeolian materials – sorted by wind

14. Influence of Parent (geological) Material
Bedrock
(Photo A.R.Aandahl)
Fluvial sediment
(river deposits)
(Photo A.R.Aandahl)
Loess (wind deposits)
(Photo A.R.Aandahl

15. Influence of Parent (geological) Material
Tidal deposits
(Photo J.C.Miller)
Tidal landscape (Stewiacke River)
(Photo J.C.Miller)

16. Influence of Climate (precipitation)

17. “Essentially, all life depends upon the soil ...
There can be no life without soil and no soil
without life; they have evolved together.”
--- Charles E. Kellogg, USDA Yearbook of Agriculture, 1938

18. Soil Ecology
The soil biological community can weigh from 1100 to 14000
kg/ha; a similar weight as 2 to 28 yearling steers!
Over 1 billion microbes in 1 tsp of a fertile soil

19. Soil biology
(soils.usda.gov/sqi/concepts/soil_biology/arthropods.html)

20. Earthworm burrows

21. Topographic (land shape) effects

22. Slope effects on soil
serc.carleton.edu/details/images/12506.html

23. Ecosystems and biology

24. Ecosystem and biology
Eastern Acid Forest Soil &
Landscape (Podzol)
Prairie Black Soil
(Chernozem)
(Photos - Agriculture Canada)
(Photos - Agriculture Canada)
Poorly drained soil
(Gleysol)

25. “The nation that destroys its soil, destroys itself.” --Franklin Delano Roosevelt
“Plowed ground smells of earthworms and empires.” --Justin Isherwood

32. Soil colour is related to organic matter
content, iron oxides, and drainage.

33. Munsell soil color charts

34. •
www.organicagriculture.co/

35. Soil organic matter
Component
Rate of
decay
• Serves as food for soil
organisms
• Stores and provides plant
nutrients
Decades
• Enhances soil structure,
porosity and water holding
capacity
Hundreds to • Holds nutrients (Cation
thousands
Exchange Capacity)
of years
• Stabilizes microaggregates
Light fraction Weeks to
months
Physically
protected
Chemically
stable
Primary Function

36. Organic matter builds structure
Sticky byproducts of decay
Soil aggregation - organic "glue" binds
mineral particles together

37. Soil organisms shape the soil
Soil aggregation - burrowing
organisms (S.S.S.A.)
Worm castes (S.S.S.A.)

38. The stability of soil structure

39. Soil Minerals
Clay Mineral
Clay Mineral (Koalinite)
Clay minerals - shrinkage & swelling

41. Soil Particle Size Classes
Most Important Aspect of Soil Texture = SPECIFIC SURFACE.
(Specific Surface = Total area on particle surfaces / total mass of particles)
Separate Class
Size (mm)
# of particles per
gram
Specific Surface
Coarse Sand
1 mm
400
22.5 cm2/gram
Fine Sand
0.1 mm
400,000
225 cm2/gram
Medium Silt
0.01 mm
400,000,000
2250 cm2/gram
"Illite" Clay
0.0001-0.001 mm
7 x 1013
1,200,000 cm2/gram
4 x 1014
8,000,000 cm2/gram
= 1/5 Acre
= ave. house lot (per gram)
"Montmorillonit
0.0001-0.002 mm
e" Clay

43. Influence of soil separates on other
soil properties (T.J. Rice, 2002)
Property
Water holding
Aeration when moist
Soil organic matter
Organic matter decomp
Warmup in spring
Shrink-swell
Compactability
Water erosion risk
Cation exchange cap.
Resistance pH change
Sand
Low
Good
Low
Rapid
Rapid
Very low
Low
Low
Low
Low
Silt
Med-high
Med
Med-High
Med
Med
Low
Med
High
Med
Med
Clay
High
Med-poor
High - Med
Slow
Slow
Mod-High
High
Low if aggreg.
High
High

44. Soil Structure (aggregation)

46. Factors influencing soil structure
Soil aggregation wetting/drying & clay content
Soil aggregation - Tillage

47. Andy’s favorite:
Solodized
Solonetic
Soil
(Found in the
prairies)

48. Cation Exchange Capacity (CEC)
CEC: The capacity of the soil to hold cations
(positively charged molecules)
Black – colloid of clays & humus with a negative
charge, attract cations (+ ions).
Molecules including nutrients in the soil come in the
form of ‘ions’, molecules with a ‘+’ or ‘-’ charge:
Cations (+): NH4+, Ca++, Mg2++, K+, Fe2++, H+, Al+++
Anions (-): HPO4-, SO4-, Cl-, HCO3-, HPO3--, OH-

49. Cation Exchange Capacity (CEC)
Black – colloid of clays & humus with a negative charge, attract cations (+ ions).
Dark blue - inner zone around the colloid has more cations (+) than anions (-). Cations
within this zone are said to be "adsorbed", or "exchangeable".
Light blue - The outer soil solution (lighter blue) has a balance of anions & cations. The
cations within this zone are "free" to move with & within soil water.

50. Soil pH
• pH: measure of the concentration of H+ in soil
solution:
pH = - log [H+]
• Therefore, low pH value, means high H+
concentration, and more acidic
• Higher concentration:
– Acidic or sour
– Corrodes metals
– Bumps desirable cations off of soil exchange
– Nutrient imbalance

52. “... only rarely have we
stood back and
celebrated our soils as
something beautiful,
and perhaps even
mysterious. For what
other natural body,
worldwide in its
distribution, has so
many interesting secrets
to reveal to the patient
observer? ” --- Les Molloy, Soils
in the New Zealand Landscape: the
Living Mantle, 1988

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54. Visit
•
•
•
•
•
•
OACC.INFO for
Production, research and market information
Upcoming workshops & symposiums
Virtual farm tours
Organic award winners
Organic policy toolbox
Monthly e-zine