Test 1 Flashcards
Soil
The earths living mantle. Its the vital link between the physical and the living world in terrestrial environments.
Soil Composition
is a dynamic, natural body composed of minerals. organic materials and living forms.
Functions of soil
- Medium for plant growth.
- Recycler of raw materials/ environmental filter
- Regulator of water supplies
- Habitat for soil organisms
- Engineering medium
Five Soil Forming Factors
- Climate (Rainfall and temperature)
- Organisms (vegetation)
- Parent material (original unconsolidated material)
- Relief-topography
- Time
Active soil forming factors
- Climate
2. Organisms
Passive soil forming factors
Parent material
relief
time
Solids
-D minerals -silicates -organic matter (carbon based)
Pores
-Air -water (dissolves nutrients)
4 major components of soils
- Minerals
- Organic matter
- Water
- Air
Soil Texture
Proportion of sand, silt and clay in the soil
soil size
less than 2mm
Sand Particles
2.0-.05mm can be seen by the naked eye and feels grity. Particles do not stick together.
Silt Particles
.05-.002mm to small to see with out microscope but feel smooth when wet.
clay particles
Soil Colloids
Anything smaller than clay. most reactive fraction of soil because of large surface area/mass ratio. usually clay minerals and organic materials
soil horizons
not in a uniform depth but it consists of layers
Master horizons
O, A, E, B, C, R
O
comprised of organic horizons that form above the mineral soil. Usually occur in forested areas and are generally absent in grassland areas.
A
Highly biological activity, including rooting. humus accumulates to darken the soil. Also a zone of leaching. Rapid weathering of minerals and leaching of soluble products by rainfall moving through the soil surface.
E
Zone where large amounts of clay and iron have been removed. E represent the word eluvial, which means removal. The E horizon is a zone of maximum leaching (eluviation).
B
Material that has leached from the A and E horizon accumulates in the B horizon. The B horizon is known as the zon of illuviation i=imput. Illuviation is the process of deposition in lower soil horizons of material eluviated from upper horizons.
C
Zone of unconsolidated soil parent material. For example, this horizon may be composed of wind-blown silt (loess), river deposits, or glacial till.
R
Consolidated hard rock
Soil Profile
a vertical section of the soil from the surface through all of its horizons. A two dimensional slice of soil.
