Soils Flashcards
What are the main mineral components that make up soil?
Sand, Silt, Clay, Oxides
What other components are present in the soil?
Half of soil = space filled with air or water
Organic matter
Humus (main source)
Layer of pure organic matter (humus)
O-Horizon
Sand, clay, oxides, and humus
What does it make?
A-Horizon (topsoil)
Sand, clay, and oxides
What does it make?
B-Horizon (subsoil)
Weathered bedrock
C-Horizon
What are some examples of how bedrock chemistry can affect the fertility of soil?
Can provide the chemicals plants need to grow (N, P, and K) Example: volcanic ash Sometimes lacks natural fertilizers Example: quartz sand Can contain toxic metals (Mg, Cr) Example: Peridotite
How does topography affect the thickness of soil?
Steep mountain slopes lose soil constantly
Flat plains allow the soil to stay in place and grow
How does a dry climate affect both the fertility and thickness of soil?
Very little soil
Salts in soil water precipitate to form CALICHE or hardpan
How fast does soil form?
Very slow
What activities destroy soil?
Grazing, farming, and deforestation
Steps of Soil Construction
Barren rock
Soil Crust
Thin soil
Thick soil
Soil Variability
USA has:
Thick ice, age soils
Soil Variability
China has:
Thick soil from floods
Soil Variability
Africa has:
Poor clay-oxide soils
