SCSC 301 TAMU Test 1 questions with
correct answers
Principle Components of Soil - ANSWERS✔✔ -Air 25%
-Water 25%
^ (healthy soil composition, those two vary from 50-0% to 0-50%)
-minerals ~45%
-Organics ~5% (again healthy soil it varies)
% are by volume not mass
Soil - ANSWERS✔✔ Dynamic natural body having properties due to the combined
effects of climate and biota as modified by relief acting on parent material over
time.
5 thing that affect soil - ANSWERS✔✔ Active:
-climate
-biota
Passive:
-parent material
-time
Modifying:
-relief (topography)
Biosphere - ANSWERS✔✔ from roots to canopy, all things living
Atmosphere - ANSWERS✔✔ from top soil on up
Lithosphere - ANSWERS✔✔ from top soil down
,Soil - ANSWERS✔✔ from top soil to bedrock
Functions of Soil - ANSWERS✔✔ Medium for plant growth
-Nutrients
-Support
-Water
-Oxygen (more absorbed through roots than leaves)
Regulates water flow (erosion)
Habitat for soil organisms (10^8-9 microorganisms in one gram of soil)
Engineering medium (build with or on)
Soil Profile - ANSWERS✔✔ a vertical section of soil through all its horizons and
extending into the parent material
Solum - ANSWERS✔✔ horizons A and B
Soil Horizons - ANSWERS✔✔ layer of soil about parallel to the soil surface, differing
in properties and characteristics from adjacent layers above or below it.
Parent Material - ANSWERS✔✔ The bedrock that lies beneath the soil horizons. Can
be termed either C or R.
-C: bedrock can be dug when wet
-R:solid rock
Eluviated - ANSWERS✔✔ A horizons, clay moves out of it
Iluviated - ANSWERS✔✔ B horizons, clay moves into it
Pedon - ANSWERS✔✔ Smallest 3-d unit of soil measurments with all characteristics
of soils. (smallest pedon is 1m^2 and 2m deep)
, Regolith - ANSWERS✔✔ everything unconsolidated; A,B, and C horizons but never R
horizon.
Colloids - ANSWERS✔✔ smallest soil particle (clay sized)
-suspended in h2o
-very small
-large surface area per size
-very reactive
Abundance of Elements in Crust - ANSWERS✔✔ 1. Oxygen
*2. Silicon
3. Aluminum
*4. Iron
*5. Calcium
*6. Magnesium
*7. Sodium
*8. Potassium
* = plant essential nutrients that come from the soil
Groups of Minerals - ANSWERS✔✔ Silicates
Oxides
Carbonates
Phosphates
Sulfates
Halides
Silicates - ANSWERS✔✔ -Quartz (SiO2) - dominate sands, very resistant
-Feldspars such as orthoclase, KAlSi3O8
-Amphiboles, pyroxenes, micas
correct answers
Principle Components of Soil - ANSWERS✔✔ -Air 25%
-Water 25%
^ (healthy soil composition, those two vary from 50-0% to 0-50%)
-minerals ~45%
-Organics ~5% (again healthy soil it varies)
% are by volume not mass
Soil - ANSWERS✔✔ Dynamic natural body having properties due to the combined
effects of climate and biota as modified by relief acting on parent material over
time.
5 thing that affect soil - ANSWERS✔✔ Active:
-climate
-biota
Passive:
-parent material
-time
Modifying:
-relief (topography)
Biosphere - ANSWERS✔✔ from roots to canopy, all things living
Atmosphere - ANSWERS✔✔ from top soil on up
Lithosphere - ANSWERS✔✔ from top soil down
,Soil - ANSWERS✔✔ from top soil to bedrock
Functions of Soil - ANSWERS✔✔ Medium for plant growth
-Nutrients
-Support
-Water
-Oxygen (more absorbed through roots than leaves)
Regulates water flow (erosion)
Habitat for soil organisms (10^8-9 microorganisms in one gram of soil)
Engineering medium (build with or on)
Soil Profile - ANSWERS✔✔ a vertical section of soil through all its horizons and
extending into the parent material
Solum - ANSWERS✔✔ horizons A and B
Soil Horizons - ANSWERS✔✔ layer of soil about parallel to the soil surface, differing
in properties and characteristics from adjacent layers above or below it.
Parent Material - ANSWERS✔✔ The bedrock that lies beneath the soil horizons. Can
be termed either C or R.
-C: bedrock can be dug when wet
-R:solid rock
Eluviated - ANSWERS✔✔ A horizons, clay moves out of it
Iluviated - ANSWERS✔✔ B horizons, clay moves into it
Pedon - ANSWERS✔✔ Smallest 3-d unit of soil measurments with all characteristics
of soils. (smallest pedon is 1m^2 and 2m deep)
, Regolith - ANSWERS✔✔ everything unconsolidated; A,B, and C horizons but never R
horizon.
Colloids - ANSWERS✔✔ smallest soil particle (clay sized)
-suspended in h2o
-very small
-large surface area per size
-very reactive
Abundance of Elements in Crust - ANSWERS✔✔ 1. Oxygen
*2. Silicon
3. Aluminum
*4. Iron
*5. Calcium
*6. Magnesium
*7. Sodium
*8. Potassium
* = plant essential nutrients that come from the soil
Groups of Minerals - ANSWERS✔✔ Silicates
Oxides
Carbonates
Phosphates
Sulfates
Halides
Silicates - ANSWERS✔✔ -Quartz (SiO2) - dominate sands, very resistant
-Feldspars such as orthoclase, KAlSi3O8
-Amphiboles, pyroxenes, micas
