1. Soil Science Chapter 14 (R&B) Chapter 14 (Miller) Ch 21 (R&B)
Some diagrams and information in this presentation have been used and/or modified with permission from Dr. Greg Pillar, Soil & Environmental Science professor at Queens University in Charlotte, NC.

2. Your Responsibility!!! SOIL READING GUIDE
Major Soil Groups
Soil Problems
… in both R&B and Miller books! 2

3. The Rock Cycle Erode & Weather SEDIMENT Cool & Harden Melt
IGNEOUS
ROCK
SEDIMENTARY
METAMORPHIC
Erode & Weather
SEDIMENT
Cool & Harden
Compaction & Cementation
Melt
Erode & Weather
Heat & Pressure
Erode & Weather
MAGMA
Melt
Heat & Pressure
Melt

4. What is SOIL????
The relatively thin surface layer of the Earth’s crust consisting of mineral and organic matter.

5. Q: What’s the difference between soil and dirt?
Soil is not DIRT!
Q: What’s the difference between soil and dirt?
A: Location,
location, location!

6. The 5 Soil-Forming Factors
Formed from parent material (bedrock) that’s slowly broken down through weathering processes.
climate (water, wind, temperature)
biology (macro- and microorganisms, plants)
relief (topography)
parent material (rocks/minerals)
time
Which is the MOST important??
CLIMATE!!!

7. How would you describe soil?
What is Soil?
How would you describe soil?
Color
Texture
Texture
Dr. Greg Pillar, Queens College

8. Goethite: yellowish brown Ferrihydrite: reddish brown
Why the color?
Hematite:
red
Goethite: yellowish brown
Ferrihydrite: reddish brown
Calcite: off white
Quartz: white
Organic matter: black
Dr. Greg Pillar, Queens College

9. Soil Color Variation Did you know ??????
There are more than 20,000 different soil types in the United States
….and each one tastes different 9

10. Dr. Greg Pillar, Queens College10

11. Soil Composition Mineral matter comes from parent material
Air & Water percents are interchangeable
Humus is organic matter!
Water
(~25%)
Humus
(~5%)
Air
(~25%)
Mineral
(~45%)

12. Soil Composition continued…
Mineral Matter
Provides nutrient minerals for plants
Provides pore space for water & air
Older soils are:
More weathered
Lower in certain
essential nutrient minerals
Humus: black/dark brown organic material remaining after decomposition
Leaf litter, animal dung, & decaying organisms
Increases the soil’s water-holding capacity by acting like a sponge

13. Soil Organic Matter In USA

14. Soil Composition continued…
Porosity
POROSITY =
amt of soil pore spaces
Pore spaces occupy ~50% of a soil’s volume
Filled with varying proportions of soil water and soil air
Soil Air contains the same gases as atmospheric air, but in different proportions.
More CO2 and less O2
(from organism respiration)
Some bacteria need nitrogen (why??)
The CO2 can accelerate weathering
CO2 + H2O  H2CO3
(carbonic acid)

15. Soil Composition continued…
As water infiltrates the soil, it can carry dissolved materials with it.
Leaching: Removal of dissolved materials from the soil by water percolating downward
Illuviation: Deposition of leached material in lower layers
Some substances completely leach out of the soil because they’re so soluble that they migrate right down to the groundwater.

16. Observe this SOIL PROFILE through soil
O: Organic material
(may be absent)
A: Topsoil - Organic material & mineral grains
E: Leached zone
(may be absent)
B: Subsoil – rich in clay, iron, aluminum
C: Weathered bedrock
Soil layers are horizons and assigned letters
R: Bedrock
(parent material) 16

17. Fun Fact: It takes 200 to 1,000 years to form an inch of topsoil.
Soil Color by Horizon
Fun Fact: It takes 200 to 1,000 years to form an inch of topsoil.
A horizon: organic coatings
B horizon: Iron coatings
C horizon: little coating

18. Soil Color – Variation by Geography
Red soils:
Southeast US
Dr. Greg Pillar, Queens College

19. Soil Color – Variation by Geography
Brown/black soils:
Midwest
Dr. Greg Pillar, Queens College

20. Soil Color – Variation by Geography
White (gypsum) sands:
New Mexico
Dr. Greg Pillar, Queens College

21. Soil Organisms
Ex: bacteria, fungi, algae, microscopic worms, protozoa, plant roots, insects, earthworms, moles, snakes, groundhogs, etc.
Soil organisms provide several Ecosystem Services (important environmental functions).
maintaining soil fertility
preventing soil erosion
breaking down toxic materials
cleansing water
affecting atmospheric composition

22. Earthworms & Ants: Mycorrhizae Cycle minerals Aerate the soil
Decomposing corpses contribute organic matter
Assist plants in reproduction by burying seeds
Mycorrhizae
Symbiotic relationship between fungi and the roots of vascular plants
Fungus absorbs nutrients from the soil, and provides it for the plant.
Plant produces food (photosynthesis), and provides it for the fungus.

24. Physical Soil Properties
PHYSICAL properties:
Texture (%sand, silt, clay)
Porosity & Permeability
Ionic Charge

25. Physical Property: Texture
Texture is determined by its % sand, silt, and clay.
Texture determines the type of soil, and the soil’s properties.
Loam: ideal for agricultural soil

26. Q: What did the shy pebble say to the big rock?
Soil Components
Q: What did the shy pebble say to the big rock?
Do you think I’ll ever
be a little boulder?
Dr. Greg Pillar, Queens College

27. Dr. Greg Pillar, Queens College
Fine Texture - Clay
Dr. Greg Pillar, Queens College

28. Dr. Greg Pillar, Queens College
Course Texture - Sand
Dr. Greg Pillar, Queens College

29. The relative portions of sand, silt, and clay-sized particles
Soil Texture
The relative portions of sand, silt, and clay-sized particles
Sand: 2.0 – 0.05 mm
Silt: 0.05 – mm
Clay: < mm

30. Soil Texture Diagram Practice
What type of soil has:
20% clay, 40% silt, 40% sand
40% clay, 10% silt, 50% sand
30% clay, 60% silt, 10% sand
Find the % of each particle at: A B C
(1) Loam
(2) Sandy clay
(3) Silty clay loam B A C
60%clay, 20%silt, 20%sand
30%clay, 40%silt, 30%sand
10%clay, 30%silt, 60%sand

31. Why is Soil Texture Important?
PROPERTY
SAND
SILT
CLAY
Water holding
Low
Med-high
High
Aeration
Good
Med
Poor
Nutrient supplying
Pollutant Filtering

32. SOIL TOUCHY
FEELY TIME!

33. Physical: Porosity & Permeability again… Think it is important??
Definition?
amt of soil pore spaces
Permeability
Definition?
ability of water to percolate through
____ porosity = ____ permeability

34. Physical: Ionic Charge
Soil minerals are often present as ions.
Minerals ions are either positively or negatively charged.
Clay particles have mostly negative charges on their outer surfaces.
Positively charged mineral ions are attracted to the soil particles and are held for plant use.
potassium K+ and magnesium Mg2+
Negatively charged mineral ions are repelled by the soil particles and are washed away from roots.
nitrate NO3-

35. Physical Characteristics (review)
Why would 100% sand be undesirable for plants?
Why would 100% clay be undesirable for plants?
Answer SAND / SILT / CLAY for the following:
A soil with a lot of _____ would have good drainage, but poor nutrient-holding characteristics.
A soil with a lot of _____ would have poor drainage, but good nutrient-holding characteristics.
A soil with a lot of _____ would have low porosity.
A soil with a lot of _____ would have high permeability.

36. Demonstration Two soil cores Bottom of core contains filter paper and
cheese cloth 36

37. Demonstration Two unknown liquids Liquids passed through soil cores
Leachate
collected below
Pollutant #2
Pollutant #1 37

38. Demonstration What happened to the original liquids? What does
a change or no change
in color mean?
Soil
Soil
To what extent did the
soil contribute to
this change? 38

39. Adsorption of Organic Dyes
CR-
Chlorophenol red
MB+
Methylene blue

40. CR-
MB+
MB+
Soil

41. Chemical Property: Acidity
Most soil pH is Plants are happiest at 
Plants are affected by soil pH.
(1) The solubility of certain nutrient minerals varies with differences in pH
Low pH = Al & Mn are more soluble, and can be absorbed in toxic amounts.
High pH = some salts are less soluble, and are less available to the plants.
(2) Soil pH affects the leaching of nutrient minerals.
Acidic soil = positively charged ions are less soluble and are unavailable for plants.

42. What is Soil?

43. 1 teaspoon of good soil contains more than 1 million bacteria!
Why is Soil Important?
1 teaspoon of good soil contains more than 1 million bacteria!
There are more living organisms in a cubic foot of soil then all of China!
Soil supports
life
L. Clarke and Corbis, 2008

44. Soil stores important nutrients
Phosphorus (P)
Nitrogen (N)
Potassium (K)
Calcium (Ca)
Magnesium (Mg)

45. Dr. Greg Pillar, Queens College
Soil Holds Water
Dr. Greg Pillar, Queens College

46. Soil provides support for buildings

47. Soil filters, buffers, detoxifies….

48. Soil Pollution Part II
Chapter 21 (R&B) 48

49. Soil Pollution
= any physical or chemical change in soil that adversely affects the health of plants and other organisms living in and on it.
Many soil pollutants…
ARE MOBILE!
move into groundwater, surface water, or air
ARE PERSISTENT!
seep into tiny cracks called micropores and adhere to the soil particles
COME FROM FERTILIZERS / PESTICIDES!
CAN ACCUMULATE!
Sustainable Agriculture practices can help…
…more on this later… 49

50. Salinization of Irrigated Soil
Irrigation water soaks through the soil area where the plant roots grow, adding to the existing water.
The additional irrigation water causes the underground water-table to rise, bringing salt to the surface.
QUESTION?!?! WHAT IS IRRIGATED SOIL?
Soil that has been hydrated from an anthropogenic source- NOT rain!
QUESTION?!?! IS IRRIGATED SOIL GOOD OR BAD?
Good: crops receive needed water
Bad: water has a much higher salt concentration than rain
When the irrigated area dries & the underground water table recedes, salt is left on the surface soil.
Each time the area is irrigated this salinity process is repeated.
ALL IRRIGATION WATER CONTAINS SOME DISSOLVED SALTS. 50

51. Salinization of Irrigated Soil
This is in Australia – occurred not from irrigation, but from lack of water-loving plants.
Extra water flows through the soil, mixing w/ salt underground, and bringing it to the surface.
Irrigation salinization is basically the same concept, and the ground would look just like this. 51

52. Effects of Salinized Soil on Plants
Normally, the water concentration inside plant cells is lower than that in the soil resulting in a net movement of water into the root cell.
When soil contains a high amount of salt, its relative water concentration can be lower than the water concentration inside cells. This causes water to move out of the roots into the soil, even when the soil is wet. 52 52

53. Soil Remediation
Until recently, the only way to remove soil contaminants was to…
Why is this a bad thing to do??
Impractical, kills all beneficial organisms, creates waste, expensive…
DIG IT UP
& INCINERATE IT! 53

54. Soil Remediation Techniques
In Small Groups: define these, then make a pro/con list. Use your book if necessary.
Dilution
Add lots of water; leach out pollutants
Vapor extraction
Inject air into soil to remove volatile organic compounds
Bioremediation
Use microorganisms to degrade organic contaminants
(oil, sludge)
Phytoremediation
Use plants to absorb contaminants such as salts or heavy metals. 54

55. DILUTION: Pump & Treat / Soil Washing
Water
Extraction well
GROUND LEVEL
Pollutant low sorption potential = not attracted to soil
easily washed away
Pollutant high sorption potential = attracted to soil
NOT easily washed away 55 55

56. … But what’s the problem here?
GROUND LEVEL
How can this problem be fixed???
Source Identification and Removal !!!! 56 56

57. Bioremediation (Bioventing)57 57

58. ACTIVITIES THAT THREATEN SOIL
15.06.b
OVERGRAZING
FARMING/AGRICULTURE
SOIL CONTAMINATION
REMOVING VEGITATION
NOTES
Overgrazing: Namibia, southern Africa
Clear cutting: Mount Rainer, Washington
Terracing to prevent erosion: Peru
Soil contamination (salt build up and pesticides): Colorado 58 58

59. PREVENTING SOIL EROSION
Agricultural: 10% of the worlds best agricultural land damaged due to soil erosion and overuse over last 50 years.
contour plowing
no-till agriculture (no plowing)
terracing slopes
crop rotation - fallow 59 59

60. Salinization Lab  Answer Prelab Questions Gather Materials
4 ziploc bags
20 radish seeds
4 paper towels
Follow instructions on the lab sheet
BE SURE TO LABEL YOUR BAGS!!!
Leave them in the box in the front.
We’ll inspect their germination progress and take data over the next week. 60

61. Your Responsibility!!! Soil Reading Guide
Major Soil Groups
Soil Problems
Soil Conservation & Regeneration
… in both R&B and Miller books! 61

62. Soil Pedon USDA Soil Profile Activity: