Soil Resources Flashcards
List 5 soil forming factors
- Parent Material
- Organisms
- Climate
- Topography
- Time
The process when rocks physically disintegrate and chemically decompose
Weathering
Physical weathering
The processes that cause rocks to disintegrate into smaller particles by some mechanical means (ex: plant roots, freezing/thawing rocks,
confining pressure…)
Chemical Weathering
The process where individual mineral grains within a rock decompose due to chemical reactions.
Why does climate play an important role in chemical weathering?
Because many of the chemical reactions involving rock forming minerals are affected by temperature and the presence of water.
The mineral ______________ is resistant to chemical weathering.
Quartz
Name 2 silicates that weather to form clays.
- Feldspar
- Ferromagnesian silicate minerals
Horizontal layers within the soil zone that form as the result of chemical and biological processes and physical transport of material vertically within the soil.
Soil Horizons
List the 6 soil horizons in order from top to bottom
O
A
E
B
C
R
Describe soil horizon O
~Loose and partly decayed organic matter
~Blackish brown color due to decaying plant matter
Describe soil horizon A
~Mineral matter mixed with some hummus
~Blackish brown color due to decaying plant matter
Describe soil horizon E
~Zone of eluviation and leaching
~Appear whitish or blonde because they lack pigmenting materials (oxide minerals have been leached and transported downward by infiltrating water)
Describe Soil Horizon B
~Accumulation of clay, iron and aluminum from above, zone of illuviation and known as zone of accumulation
~Exhibit a range of colors because they represent the zone where various oxide materials accumulate withing the soil profile. The specific color of B horizons varies on the presence of free oxygen.
~The color of B horizon is a useful indicator as to the level of drainage and saturation within a soil.
Describe soil horizon C
Partially altered parent material
Describe soil horizon R
Unweathered parent material, bedrock
In addition to horizons, other important soil characteristics are color, structure and _________.
Texture
Is soils classified loam or sandy loam considered to be a better agricultural soil? And why?
Loam since they provide the best combination of drainage and fertility.
A soil characteristic that refers to the way in which the soil particles themselves are arranged.
Soil Structure
What is peds or aggregates?
When previously undisturbed soil is dug up, it will naturally break up into separate clumps that can take on different shapes.
What is the soil classification system used by scientists?
Soil Taxonomy
What 2 things is soil taxonomy based on?
- Characteristics of the horizons found in particular soil
- Soil’s temperature and moisture regime
The engineering classification of soils is based on ___________________ properties.
physical
Name the 7 Soil Properties
- Porosity
- Soil moisture and drought resistance
- Permeability
- Plasticity
- Compressibility
- Shrink-swell
- Ion exchange capacity
What is cohesive vs. adhesive forces?
Cohesive: Same molecules attracted to each other, such as water attracted to water through hydrogen bonding
Adhesive: One substance attracted to another substance, such as water attracted to the glass
Texture refers to the amount of ________, _________________, and ________-________ material within a particular horizon,
sand, silt and clay-sized material
Name 2 specific ways is soil used as a resource?
- Farming
- Several important mineral and energy resources (aluminum, bauxite)
Why is teh loss of organics in soil loss so important?
Organics and clay minerals are what make the soil so rich in the first place.
Name the 9 soil mitigation techniques.
- contour plowing
- Strip cropping
- No till farming
4.Grassed waterways - Terracing
- Stream buffers
- Silt fencing
- Retention basins
- Slope vegetation cover
What is a paleosol?
A soil sequence that has been buried during some geologic event, representing a distinct time marker that can be useful in scientific investigations.
