1. SOIL

2. mixture of eroded rock, mineral nutrients, decaying organic matter, and billons of living organisms (mostly decomposers)
SOIL

3. Formation of soil takes….
And depends on
even up to a 1000 years for 1 inch!

5. darker = more nutrients (N)
Soil Horizons layers of soil based upon…… color, size, texture, structure, consistency, root quantity, pH, and voids.
O horizon = Organic materials; leaf litter, waste, dark brown/black
A horizon = topsoil; location of most organisms, humus (decomposed organic matter with inorganic minerals)
darker = more nutrients (N)
B horizon = subsoil; mostly inorganic, made of weathered rock; lighter color due to less organic matter
Soil horizon development animation
Leaching  removal of soil materials dissolved in water, occurs mostly between A & B
C horizon = weathered bedrock
R horizon = unweathered bedRock

6. Variations with Climate and Biomes
Soil formation greatly depends on the climate, and soils from different biomes show distinctive characteristics.
Temperature and moisture affect weathering and leaching. Wind moves sand and other particles, especially in arid regions where there is little plant cover. The type and amount of precipitation influence soil formation by affecting the movement of ions and particles through the soil, aiding in the development of different soil profiles.

7. Soil Profiles in Different Biomes
Mosaic
of closely
packed
pebbles,
boulders
Weak humus-
mineral mixture
Dry, brown to
reddish-brown, with
variable accumulations
of clay, calcium
carbonate, and
soluble salts
Desert Soil
(hot, dry climate)
Grassland Soil
(semiarid climate)
Alkaline,
dark,
and rich
in humus
Clay,
calcium
compounds

8. Tropical Rain Forest Soil (humid, tropical climate)
Acidic
light-
colored
humus
Iron and
aluminum
compounds
mixed with
clay
Forest litter
Leaf and
mold
Humus-mineral
mixture
Light, grayish-
brown, silt loam
Dark brown
firm clay
Tropical Rain Forest Soil
(humid, tropical climate)
Deciduous Forest Soil
(humid, mild climate)
Coniferous Forest Soil
(humid, cold climate)
Acidic litter and humus
Light colored and acidic
Humus with iron and aluminum compounds

9. Soil Characteristics

10. Texture
Based on the size and amount of the particles that make up the soil

11. Texture is determined by one of two methods…….
Ribbon Test
The more clay in the soil the
longer the “ribbon” may be

12. Soil Triangle 2. Mason Jar test Mix sample with water and let sit
overnight. Measure the depth of
each layer and use the soil triangle
to ID the texture

14. Soil Properties Affected by Soil Texture
Porosity refers to that part of a soil volume that is not occupied by soil particles or organic matter. Pore spaces are filled with either air, other gases, or water. Large pores allow the ready movement of air and the drainage of water.

15. Soil Properties Affected by Soil Texture
Permeability- rate at which water and air move from upper to lower layers
Permeability ANIMATION

16. Soil Properties Affected by Soil Texture
LOAM= between silt and clay (inorganic); crumbly, spongy texture; excellent for plant growth

17. Soil pH (Alkalinity/Acidity)
directly affects the availability of plant food nutrients and survival of bacteria
Too acidic or basic will not
Allow compounds to dissolve
Allow presence of certain ions
Each plant has an ideal pH range, most between 6 and 8

18. Ex. If natural or anthropogenic acid deposition lowers the pH of soil it increases the solubility of Aluminum. This in turn inhibits the growth of plants.

19. Is your soil too acidic or alkaline?
If soil is too acidic, add ground limestone/lime (CaCO3)
If soil is too basic, add organic material like steer manure

20. Major Nutrients Nitrogen Stimulates above ground growth
Produces rich green color
Influences quality& protein content of fruit
(Taken up by plants as NH4+ and NO3-)
Phosphorus
Strong root system
Increases seed yield & fruit development
Component of ATP
Potassium – AKA potash
Improves color of flowers
Improves quality of fruit
Offsets too much N

21. Is your soil low in nutrients? Try….
1. Inorganic fertilizer (man made) OR

22. 2. Organic fertilizer compost
refers to the how the fertilizer was made…. naturally
compost
Consequence of overuse of ANY fertilizer through runoff or leaching extra nutrients the plants cannot absorb could end up in waterways and lead to eutrophication

23. Soil Problems

24. Soil Problems are most common in
Tropical Rainforests
Arid Areas - Sub-Saharan Africa
American West & Midwest

25. Land Degradation is the number one cause of the soil problems of the world
When human or natural activities damage land to the point it cannot sustain its ecosystem

26. Areas of serious concern
Areas of some concern
Stable or nonvegetative areas

27. 1. Erosion
Transport of sediment from one location to another usually by wind or water
Sheet erosion
uniform removal of sediment
Gully erosion
Rill erosion
Water coalesces into small channels
large channels are formed

28. Farming practices usually increase erosion b/c plowing loosens topsoil and removes plants
The American Dust Bowl

29. Agricultural practices to conserve soil……
Shelterbelts/ windbreaks
Strip cropping & contour plowing
Terracing
Alleycropping/ intercropping
Conservation tillage/ No till

30. Accumulation of salts in the soil, stunts plant growth, lowers crop yields, and can kill the plants
2. Salinization
Major issue in areas that irrigate with water that is “saltier” than rain water.
Ex. Ca and Az
WHY??

31. WATERLOGGING  too much water in the root zone of a plant
To prevent salinization, farmers may irrigate more to leach the salts deeper into the soil away from the roots. If there is not proper drainage this may cause…..
WATERLOGGING  too much water in the root zone of a plant
Inundation of fields is a sign of waterlogging occurring beneath the surface.

32. When land in arid or semi arid areas becomes more desert-like
3. Desertification
Causes
Consequences
Overgrazing
Deforestation
Surface mining
Erosion
Salinization
Soil compaction
Worsening drought
Famine
Economic losses
Lower living
standards
Environmental
refugees