1. Soils NOT Just Dirt
Chapter 8

2. Defining Soil
“a natural body consisting of layers (horizons) of mineral and/or organic constituents of variable thickness, which differ from parent material in their morphological, physical, chemical, and mineralogical properties and their biological characteristics”
Birkeland, 1999; Joffe 1949
I need a brave student to read this slide for me. I am not too good with names but you can read them at the end there. Do you think they wrote a definition this long and weird sounding definition just to freak out high school students? No, each part is really important so lets break it down.

3. Why not Dirt? Soil is a living environment Has nutrients
Earthworms and insects
Diverse
Bacteria
Layers
Have the words come in after you have asked what the students think: Why do you guys think soil is different from dirt? I want about 5 difference answers so everyone better be thinking of something

4. Soil Importance Medium for plant growth Water purifier
Facilitates waste decomposition
Viewing a world without soil.
No plants so not sufficient amount of oxygen
Ground water and aquifers are toxic and gross
Nothing decomposes

5. Water Purification Natural filtration
Chemical absorption and adsorption
Living organisms
Human interaction and manipulation of soils can interrupt the process of natural water purification.

6. ORGANIC RICH
SOIL

7. How Soils Form
There are multiple processes happening at the same time to allow soil to form.
Parent Material
Climate
Topography
Organisms
Time
Pedogenic regimes: Remember the part of the definition I wanted you to remember? What was it? And why do you think I am asking you now
Soil Succession: Primary = 1000 years, soil is not present and in a lifeless and barren area. Secondary = some soil is already present years
Clay Factories = weathering of primary materials and formation of clay materials shows stability of soil formation
Complexity = different factors that happen over a long period of time
Energy = always need energy. What type of energy process might occur to produce soils?

8. Average Soil Sample Contains
What is mineral?
Solid inorganic substance of natural occurrence

9. Soil Horizons O – Organic: leaf litter and humus
Basics
O – Organic: leaf litter and humus
A – Topsoil: seeds germinate and plant roots grow, made of humus and mineral B – Subsoil: clay and mineral deposits C – Regolith: slightly broken up bed rock, plant roots cannot break through
Picture is called a soil profile
Humus = decompose organic matter
B: mineral deposits come from mineralized water that drips from the layers above
C: very little organic matter

10. Categorizing Soil Color Density Texture Temperature Structure Moisture
Porosity

11. Color
Munsell System quantitatively measures differences in color characteristics
It measures
Hue: yellow, red, blue, green
Value: high value= light colored, low value = dark colored
Chroma: purity of color, high chroma = pure color, low chroma = less pure
Yellow and red are dominate hues, blues and greens are waterlogged soils
Reason for value being opposite is that we are looking at the function of the amount of light reflected
Less pure is diluted by grey

12. Evaluating particle size
Texture
Evaluating particle size
Gravel feels coarse
Sand feels gritty
Silt feels like flour
Clay feels sticky and wet

13. Soil types

14. Too Much Sand
Soils with lots of sand have to much space between particles. This makes it hard for them to hold water or any nutrients. Plant’s roots cannot hold well.
Soils with lots of sand have to much space between particles. This makes it hard for them to hold water or any nutrients. Plant’s roots cannot hold well.

15. Too much Silt
Soils with too much silt is very light. Commonly found in flood plains and is the components of soil that makes mud. Lots of silt makes excellent farmland, but increase erosion. This is that part of soil that blows away in sand storms
Soils with too much silt is very light. Commonly found in flood plains and is the components of soil that makes mud. Lots of silt makes excellent farmland, but increase erosion. This is that part of soil that blows away in sand storms

16. Too Much Clay
Soil with too much clay is heavy and dense. There is almost no space between the particles. Bacteria and microorganisms in the soil cannot get oxygen. Plant roots cannot push through.
Soil with too much clay is heavy and dense. There is almost no space between the particles. Bacteria and microorganisms in the soil cannot get oxygen. Plant roots cannot push through.

17. That’s Just Right
LOAM
Perfect soil for plants has about equal parts sand and silt with less clay. There is large enough space between particles for air, water, and nutrients. There should be enough clay to help stick together.
Perfect soil for plants has about equal parts sand and silt with less clay. There is large enough space between particles for air, water, and nutrients. There should be enough clay to help stick together.
Everything is good. Plant roots can grow. Farmers and gardeners get really happy and proud of this type of soil

18. Structure Effected By: Chemicals Biological activity Soil use
Water content
Overburden
Texture

19. Porosity Fraction of void space in the material
Can contain water or air

20. Permeability
Is the relative ease in which water and air can move through soil. Soils with low permeability do not have much drainage.

21. Density Less dense More Dense Someone tell me what density is
Based on your previous knowledge of density “Which do you think is more dense?”
Less dense
More Dense

22. Temperature Becomes important with seed germination and crop growth
Minimum temperature
Optimum range of temperature
Optimum temperature
Maximum temperature
Measured with thermometer placed 3 to 4 inches into the ground
Lettuce and Spinach have the lowest minimum temperature at 35
Turnips, watermelon, okra, cucumber, and corn have the highest maximum temperature at 105
Optimal temperatures range from 65 to 95
Temperature can vary throughout the year or latitudinally

23. Moisture
Moisture is key to controlling the exchange of water and heat energy between land surface and atmosphere

24. Acidity in Soils pH measures the acidity or alkalinity of soil
Neural = 7.0
Acidic < 7.0
Alkaline > 7.0
Effects solubility of plant nutrients
Soils normally range from pH
Most cultivated plants like slightly acidic soil
pH 0-14
Before a nutrient can be used by a plant it most be dissolved in the soil solution

25. Soil Erosion
Soil degradation is the loss of some or all of the ability of soils to support plants. One of the major causes is erosion. It can take centuries for lost topsoil to be replaced.