GEOG 1266 Lecture Notes - Lecture 6: Soil Science
13 Jun 2018
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GEOG NOTES 4/23
SOILS
I. Definitions
a. Soil – elements and minerals/particles – organic matter - of earth’s surfae that
opose the Earth’s rust
i. His definition: A combination of mineral and organic matter formed at
earth’s surfae ad apale of supportig plats.
ii. Soil is the hidden secret friend that is the root domain of lively darkness
and silence
b. Francis D. Hole – pedologist – soil scientist – Quaker – often spoke to children
about soil, made Wisconsin adopt the first state soil, now every state has one
c. ON exam – shows slides of soils and you must identify
II. Properties
a. Horizons
i. A – at the surface – dark in color, high in organic
matter, contains most of the roots
ii. E – eluvial horizon – pale in color, depleted in Fe3+,
Al3+, clay, and organic matter
iii. B – subsurface horizon – brownish/reddish, often
enriched with Fe3+, Al3+, clay
iv. C – Subsurface horizon – weathered paret
aterial (rok or sediment)
v. R-rock
vi. O-organic Material
*Not all soils contain all these horizons
*Horizon boundaries are not usually clear- gradual/ difficult to agree upon
*Horizons may be subdivided
*Also subordinate designations – lowercase horizons too
b. Color
i. Reds, browns, etc.
ii. Dark color indicates organic matter
iii. Red color indicates presence of iron oxide, Fe3+
iv. Blue/Grey colors indicate iron in its reduced state, Fe2+
v. Pale colors indicate absence of organic matter and absence of iron
vi. White indicates presence of calcium carbonate CaCo3
vii. Munsel soil color chart
c. Texture
i. Sand vs. Silt vs. Clay- memorize the boundary in size between these kinds
ii. Texture - Relative percentage of sand/silt/clay in the soil/horizon
iii. Loam – mixture of sand/silt/clay – agriculturally good mixture
d. Structure
i. PED- naturally occurring aggregate of soil
O
A
E
B
C
R
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