2: How Do Soils Form?

Question 1

5 soil forming factors

Answer 1

Parent material
Climate
Organisms
Topography
Time

Question 2

4 soil forming processes

Answer 2

Addition of materials
Loss of materials
Translocations
Transformations

Question 3

Soil profile

Answer 3

The vertical arrangement of soil horizons

Question 4

Order of soil horizons

Answer 4

O: organic materials
A: topsoil
E: loss of material, eluviated zone
B: subsoil
C: weathered rock
R: solid rock

Question 5

Felsic rock

Answer 5

Made out of light elements

Question 6

Mafic rock

Answer 6

Made out of heavy elements

Question 7

6 master horizons

Answer 7

The most common horizons found in developed soils (not all are always found)

Question 8

Transition horizons

Answer 8

May be dominated by properties of one horizon but have properties of the other

Question 9

Subordinate distinctions

Answer 9

Horizon suffixes applied to further describe master horizons

Question 10

What are the 4 different unique environment distinction horizons

Answer 10

M, L, V, W

Question 11

M horizon

Answer 11

Human-made layer (asphalt, landfill, liner)

Question 12

L horizon

Answer 12

Horizon of biologically produced material deposited in water

Question 13

V horizon

Answer 13

Horizon dominated by vesicular pores

Question 14

W horizon

Answer 14

Water (liquid or frozen)

Question 15

Entisol

Answer 15

Soils with little or no profile development

Question 16

Inceptisol

Answer 16

Soils with subtle profile development

w: reddening or change in soil structure

Question 17

Andisol

Answer 17

Soils developed from volcanic ejecta and volcanic ash
High fertility

Question 18

Gelisol

Answer 18

Soils with permafrost: W layer

Permafrost is a layer of frozen soil for more than 2 consecutive years

i: slightly decomposed organic material (OM)
e: intermediately decomposed OM
f: frozen

Question 19

Histosol

Answer 19

Comprised mainly of organic vs. mineral matter
~20% or more organic

Fibric (Oi) - slightly decomposed
Hemic (Oe) - moderately decomposed
Sapric (Oa) - highly decomposed

Question 20

Aridosol

Answer 20

Desert soils, subsoil clay and carbonates/salt accumulation

V: vesicular pores
k: accumulation of CaCO3
m: cemented

Question 21

Vertisol

Answer 21

Self-churning soils by shrink-swell process

ss: slickensides (surfaces on the soil that are shiny)
BC: transitional between B and C properties

Question 22

Mollisol

Answer 22

Soils with thick surface accumulation of soil organic matter

t: illuvial accumulation of clay
k: accumulation of CaCO3
BC: transitional between B and C properties

Question 23

Alfisol

Answer 23

Soils with subsurface accumulation of clays
High base saturation (Na, K, Ca, Mg)

t: accumulation of translocated clay
1, 2: distinctive layers with different texture and/or color exist within the same horizon

Question 24

Ultisol

Answer 24

Highly weathered soils with subsurface accumulation of clay and low base saturation (low fertility)
Developed under most warm conditions. In the US only in the south east (North, South Carolina, Alabama)

i: slightly decomposed organic material (OM)
p: plowed
g: graying, prolonged soil water saturation resulting in the reduction of iron leading to dull gray coloration

Question 25

Spodosol

Answer 25

Common in boreal forests
Defined by the process of podzolization

e: intermediate decomposition
s: illuvial accumulation of Fe and Al oxides with OM
h: illuvial accumulation of humus
BC: transitional between B and C
r: soft or weathered bedrock (used with C)

Question 26

Oxisol

Answer 26

Completely weathered soils
Strongly weathered, few (<10%) weatherable minerals, predominantly Fe and Al oxyhydroxides

p: plowed
o: residual accumulation of Fe and Al oxides

Question 27

State factor equation

Answer 27

S = f(cl, o, r, p, t)

Soil is the result of climate, organisms, parent material, topography, and time