1. SOIL: Make it Work for You!
We Study Soil Because It’s A(n)
Great integrator:
all parts of ecosystem
Medium of crop production
Snapshot of geologic, climatic,
biological, and human history
Producer and
absorber of gases
Waste decomposer
Medium for plant growth
Source material for construction,
medicine, art, etc.
Home to organisms
(plants, animals and others)
Filter of water and wastes
Essential natural resource

2. SOIL: Make it Work for You!
Soil Forming Factors
Parent Material
Topography
(The first four factors over) Time
Climate
Biota
These five factors work together to create a unique soil profile made of layers called horizons.

3. SOIL: Make it Work for You!
What is “Soil?”
Each discipline defines soil in a different way, depending on how soil affects it.
“In an engineering sense, soil is the relatively loose agglomerate of mineral and organic materials and sediments found above the bedrock.”
R.D. Holtz and W.D. Kovacs (1981)

4. SOIL: Make it Work for You!
Physical Characteristics
Soil Texture, Consistency, & Structure
Soil Compaction (Bulk Density)
Soil Moisture
Nutrient Characteristics (Soil Chemistry)
Chemical bonding pH
Cation Exchange Capacity (CEC)
Nutrient Availability

5. SOIL: Make it Work for You!
Physical Characteristics of Soil:
Texture: the mineral components
Consistency & Structure: How the mineral components are put together
Bulk Density
Soil Moisture

6. SOIL: Make it Work for You!
Soil Texture:
The way the soil “feels” is called the soil texture.
Soil texture depends on the amount of each size of mineral particles in the soil.
Sand, silt, and clay are names that describe the size of individual mineral particles in the soil.
Sand are the largest particles and they fell “gritty”
Silt are medium sized, and they feel soft, silky or “floury”
Clay are the smallest sized particles, and they feel “sticky” 9 9

7. SOIL: Make it Work for You!
Soil Texture: Relative Size Comparison of Soil Particles
beachball
Sand
(feels gritty)
( mm, USDA)
( mm, ISSS)
frisbee
dime
Clay
(feels sticky)
Silt
(feels floury)
 The way a soil “feels” is called the soil texture.
 Soil texture depends on the amount of each size of particle in the soil.
 Sand, silt, and clay are names that describe the size of individual particles in the soil.
Sandare the largest particles and they feel “gritty.”
Siltare medium sized, and they feel soft, silky or “floury.”
Clayare the smallest sized particles, and they feel “sticky” and they are hard to squeeze.
(< mm, USDA)
(< mm, ISSS)
( mm, USDA)
( mm, ISSS)

8. SOIL: Make it Work for You!
Soil Texture Triangle
SiCL
% Sand
% Silt
% Clay S LS SL L
SiL Si CL
SiC C SC
SCL
100
Triangle Key:
S = sand or sandy
Si = silt or silty
C = clay
L = loam or loamy

9. SOIL: Make it Work for You!
Effects of Soil Texture:
Soils are more cohesive when they have more fine particles (Clays).
Soils are more loose when the have more coarse particles (Sand).
Different combinations of coarse and fine contents produce different soil textures.
A loam is a mixture of sand, silt and clay: sandy clay loam is best in landscapes.
Many other inclusions, such as cobbles, boulders.

10. SOIL: Make it Work for You!
Soil Consistency
Describes the general organization of the soil.
Hold a moist sample between the thumb and forefinger, and gently squeeze it until it falls apart.
The soil is classified by the following categories
Loose: You have trouble picking out a single sample and the structure falls apart before you handle it.
Friable: The sample breaks with a small amount of pressure.
Firm: The sample breaks when you apply a good amount of pressure and dents your fingers before it breaks.
Extremely Firm: The sample can't be crushed with your fingers (you need a hammer!).

11. SOIL: Make it Work for You!
Soil Consistence
Loose*
Extremely Firm
Firm
Friable
* Soils with “single grained” structure always have loose consistence.

12. SOIL: Make it Work for You!
Soil Structure: the shape that the soil takes based on its physical and chemical properties. Possible choices of soil structure are:
With Structure:
Granular
Blocky
Platy
Prismatic
Columnar
Without Structure
Single Grained
Massive 2 2

13. SOIL: Make it Work for You!
Soil Structure:
With Structure:
Without Structure
Single Grained:
beach sand
Massive
solid mass with no shape 2 2

14. SOIL: Make it Work for You!
Soil Structure: with Structure
Granular
Blocky
Prismatic
Columnar
Platy

15. SOIL: Make it Work for You!
Soil Structure: without Structure
Single Grained
Massive

16. SOIL: Make it Work for You!
Bulk Density: a measure of soil compaction
Sample is made of Solids and
Pore Spaces
1 cm. (so, there is 1 cubic centimeter of soil)
1.33 gms.
To calculate Bulk Density:
Volume = 1 cm3
1.33
Bulk Density = 1
Weight = 1.33 gms
Bulk Density =
Weight of Soil
Volume of Soil
Bulk Density =
1.33 gms / cm3

17. SOIL: Make it Work for You!
Bulk Density & Compaction Zones
Depth
Bulk Density (grams / cm3
0 inches
1.43
Plow Layer
1.90
7 inches
1.87
8 inches
Compacted Zone
9 inches
1.84
10 inches
1.80
Uncompacted
subsoil
1.60

18. SOIL: Make it Work for You!
Basic Soil Components
Soil Particles: Mineral and Organic
Pore Spaces: location of air and water

19. SOIL: Make it Work for You!
Soil Moisture: some terms and concepts
Field Capacity: water that remains in soil beyond the effects of gravity.
Permanent Wilting Percentage: amount of water after the permanent wilting point is reached.
Available Water: amount of water in the soil between the field capacity and the permanent wilting percentage.

20. SOIL: Make it Work for You!
Relationship between soil texture and water availability 4
Inches of Water Per ft. of Soil 3
Field Capacity
Available
Water 2
Permanent Wilting Percentage 1
Sand
Sandy
Loam
Silt
Loam
Clay
Loam
Clay

21. SOIL: Make it Work for You!
Soil at Different Moisture Levels:
At Saturation
At “Available Water
Water on soil
particle surface
Pore Spaces are filled with water
Pore Space

22. SOIL: Make it Work for You!
Soil at Different Moisture Levels:
At Permanent Wilt
Compacted
No water remains attached to soil particles
Pore spaces are collapsed

23. SOIL: Make it Work for You!
Compacted Zone
Impermeable Layer
H2O
Non-Compacted
Compacted

24. SOIL: Make it Work for You!
Sand Over Clay
Impermeable Layer
H2O

25. SOIL: Make it Work for You!
Clay Over Sand
Perched Water Table
H2O

26. SOIL: Make it Work for You!
Soil Sandwiches
Wet & Dry Layers
H2O

27. SOIL: Make it Work for You!
Soil Salads
Patchy Soil Moisture
H2O

28. Summary of Water Movement:
SOIL: Make it Work for You!
Summary of Water Movement:
Rate depends on:
pore space (structure) and consitence
particle sizes (texture) and particle size distribution.
Changes in bulk density:
changes water movement (e.g. compaction).
may result in perched water tables through creating an impermeable layer.

29. Surface Drainage (Run-Off)
SOIL: Make it Work for You!
Surface Drainage (Run-Off)
Severity of slopes
Angle and length of slopes
Soil or surface type
Presence or absence of vegetation
Total surface area of drainage basin
Must include structural surface area
Structures modify soil saturation, contact areas, and volume contact/unit area

30. SOIL: Make it Work for You!
Controlling Surface Drainage
Divert run-off from adjacent sites
Stabilize slopes with synthetic materials, mulches or vegetation
Break up straight line flows, slows velocity
Construct sediment fences
Line drainage channels with coarse aggregates
Contoured beds and or terracing
Re-vegetation mats
Organic vs. synthetics
Run strips parallel to slope
Soil modifications;
Replace high bulk density soils
Incorporate OM or aggregates
Break up soil surface crusts

31. Altering Subsurface Drainage
SOIL: Make it Work for You!
Altering Subsurface Drainage
Deep plowing (sub-soiling) can damage tree roots where landscape is established, utilities, impractical for small sites
Avoid abrupt changes in soil type
Incorporate OM or large quantities of aggregates
Huge variety of drains

32. SOIL: Make it Work for You!
Large Subsurface Drains
Concrete pipes
Usually for heavy traffic or very large drains
High handling and transportation costs
Large diameter - 12” to 24” diameter metal culverts
Preferred under vehicular traffic
Damaged ends hinder linking
Expensive
Smaller Subsurface Drains
Ceramic tiles, out moded
Corrugated plastic pipe
Cheap, light, flexible
Perforated - areas of collection of release
Non-perforated - transport areas
Avoid clods contacting during installation
Cover on 3 to 4 sides with 3” to 4” of aggregates
Cover with back-fill, preferably 12”+
Topsoil in non-roads, road bed material in traffic areas

33. SOIL: Make it Work for You!
French Drains
Old-fashioned, but very effective
Numerous variations;
With or without pipes
Covered or exposed
Often connected to the surface with water permeable material
Essentially a trench filled with aggregates
Always slope to a lower elevation!
Very useful for draining contained planting sites

34. SOIL: Make it Work for You!
Soil Horizons:
Horizon “A” = topsoil
Specified by texture, OM content, available nutrients and drainage characteristics.
Critical to landscape success.
Should be removed prior to construction and stock piled on site
Incorporate 1/3 into sub-soils after construction to create smoother transition zone
Sharp transition between topsoil and subsoil creates perched water tables.
Horizon “B” = transition zone
Constitutes much of the exposed soil in areas where construction has occurred and in some formerly cultivated portions of Ohio
Horizon “C” = true subsoil
Little or no soil development.
Often contains accumulated soluble salts, lime, etc. beneath cultivated areas.

35. SOIL: Make it Work for You!
Characterization and Sampling Options
Soil Pit
Exposed Profile (road cut)

36. SOIL: Make it Work for You!
Soil Chemistry
Chemical bonding pH
Nutrient Availability
Cation Exchange Capacity (CEC)

37. SOIL: Make it Work for You!
What is “chemistry?”
Elements: the simplest kind of matter. They cannot be broken down into anything simpler.
Elements can exist alone. Nitrogen (N), Phosphorus (P), Potassium (K), Oxygen (O), are elements and they can be made to exist alone, but in nature they seldom do.
Elements tend to combine with each other. These are called “compounds.” When they combine, it’s called a “chemical reaction.”

38. SOIL: Make it Work for You!
What is “chemistry?”
Chemistry is the study of the “how” and “why” elements combine, and break apart, through chemical reactions.
Soil Chemistry is simply studying how and why compounds are formed and broken apart in the soil, and how these chemical reactions affect plants.

39. SOIL: Make it Work for You!
Chemistry Made Simple: The Atom
(+) -
The Electron = negative charge
The Nucleus = positive charge
Hydrogen

40. SOIL: Make it Work for You!
Chemistry Made Simple: The Atom
(+) -
The Nucleus = positive charge
Hydrogen

41. SOIL: Make it Work for You!
A Water Molecule
H2O
(+)
Hydrogen
Hydrogen
Oxygen

42. SOIL: Make it Work for You!
What happens when an atom has too many electrons?
It has a negative charge ( - )
These atoms are called: anions
What happens when an atom doesn’t have enough electrons?
It has a positive charge (+)
These atoms are called: cations

43. SOIL: Make it Work for You!
What happens when an anion meets a cation?
Anions have a negative charge (-):
Cations have a positive charge (+):
When they meet, they combine to become a molecule, the simplest compound:
NaCl (sodium chloride = salt).
Chlorine: Cl-
Sodium: Na+

44. SOIL: Make it Work for You!
Common soil cations and anions, their chemical symbols and ionic forms

45. SOIL: Make it Work for You!
The Chemistry of Clay: - - - - - - - - - - - - - - -
Clay Particle - - - - - - - - - - -
Clay particles carry negative charges

46. SOIL: Make it Work for You!
With Magnets
In Soil
CLAY
NH4+
Ammonium
CLAY K+
Potasium
Unlikes Attract - - + +
CLAY
NO3-
Nitrate
Likes Repel - + - +

47. SOIL: Make it Work for You!
The Strange Properties of Water:
Water ionizes: it falls apart into ions.
H2O ® H+ + OH-
Called the self ionization of water.
Only a small amount.

48. SOIL: Make it Work for You!
What is pH?:
It’s simply a measure of the relative amount of H+ ions
In the soil, it is driven by the ionization of water: H2O ® H+ + OH-
We us pH to measure the acidity or the alkalinity (basicity) of a solution (a soil solution)

49. SOIL: Make it Work for You!

50. Most agricultural soils Extreme pH range for most mineral soils
Possible pH Ranges Under Natural Soil Conditions
black walnut:
Most desirable
carrot:
cucumber:
spinach:
tomato:
white pine:
Very
strong
Strong
Moderate
Slight
Neutral
Acid
Basic 3 4 5 6 7 8 9 10 11 1 2 12 13 14
Most agricultural soils
Extreme pH range for most mineral soils
cranberry:
apple:

51. SOIL: Make it Work for You!
Clay and organic particles have a negative charge
Soil reactions in neutral to high (alkaline) pH conditions -
Mg+2 H+ K+
Ca+2
PO4-3
NO3- - - - - - -
NO3- - - - - K+
Clay Particle - - - - - - - -
Al+3

52. SOIL: Make it Work for You!
Clay and organic particles have a negative charge
Soil reactions in low (acid) pH conditions - H+
Al+3 K+
PO4-3
Clay Particle
NO3-
NO3-

53. SOIL: Make it Work for You!
Physical and Chemical Characteristics of Soil: what does it all mean to you?
Soil Texture and physical nature of the soil
Water availability:
soil texture
bulk density
Soil Chemistry:
Charged elements / molecules & soil particles
pH and nutrients