Soil Flashcards
What is the study of soil?
pedology
Derivatives of pedology
Pedon (soil) and Logos (reason)
Russian soil scientist
Dokuchaev
How do soils form?
They develop over identical bedrock exposed to various climates
Who introduced the idea that climate plays a major role in soil formation to the US?
Marbut
5 Categories of Soil Influence
- Parent material
- Climate since accumulation
- Plant and animal life
- Land relief
- Time other factors have interacted
What climatic forces act on the parent material?
Precipitation, temperature, humidity, wind
What is immature soil?
Lacks well-developed layers
What is a profile?
Vertical column of soil
What are horizons in a profile?
Soil layers
What is the O Horizon?
Dominated by Organic material such as leaves, lichens, etc.
How deep is the O Horizon?
0-2 inches
What is the A Horizon?
AKA the surface layer in a soil survey, Accumulation of organic matter and minerals
In which horizon does most root activity occur in plants?
A Horizon
How deep is the A Horizon?
2-10 inches
How deep is the B Horizon?
10-30 inches
How deep is the C Horizon?
30-48 inches
What makes up the E Horizon?
Sand and silt-sized particles
What is lost in the E Horizon?
Silicate clay, iron, aluminum
Which horizon is referred to as subsoil?
B Horizon
What horizon is known as the “zone of accumulation?”
B Horizon
What is leaching?
Water moves nutrients from the A Horizon to the B Horizon
Which horizon is referred to as the “zone of leaching?”
A Horizon
Why are some minerals drawn upwards from lower soil layers?
High evaporation rates and plant absorption
What is the fragipan layer?
Dense, nearly impermeable subsurface layer
What is claypan?
Fragipan layering caused by extreme soil compactness
What is hardpan?
Cementation of soil particles
What are layers of soil cemented by calcium carbonate called?
Caliche
What are layers of soil cemented by iron oxide called?
Ironpan
What horizon is known as the substratum?
C Horizon
What is the lowest horizon?
R Horizon
a
highly decomposed organic materials
b
buried soil horizon
c
concretions — grains, pellets, or nodules of various sizes, shapes, and colors consisting of concentrated compounds or cemented soil grains
d
physical root restriction
e
organic material of intermediate decomposition
f
frozen soil
g
strong gleying — soil that is formed under poor drainage, resulting in the
reduction of iron and other elements and in gray colors and mottles
h
alluvial accumulation of organic matter
i
slightly decomposed organic matter
k
accumulation of carbonates
m
cementation
n
accumulation of sodium
o
residual accumulation of sesquioxides
p
tillage or other disturbance
q
accumulation of silica
r
weathered or soft rock
s
alluvial accumulation of sesquioxides and organic matter
t
accumulation of alluvial clay
v
plinthite
w
development of color or structure
x
fragipan character
y
accumulation of gypsum
z
accumulation of salts more soluble than gypsum
Soil separate: very coarse sand
2.0-1.0 mm
Soil separate: coarse sand
1.00–0.50 mm
Soil separate: medium sand
0.50–0.25 mm
Soil separate: fine sand
0.25–0.10 mm
Soil separate: very fine sand
0.10–0.05 mm
Soil separate: coarse silt
0.05–0.005 mm
Soil separate: fine silt
0.005–0.002 mm
Soil separate: clay
less than 0.002 mm
What is mechanical analysis?
Process by which soil separates are obtained
How many textural class names exist?
12
12 Textural Class Names
sand, loamy sand, sandy loam, sandy clay loam, sandy clay, clay, clay loam, loam, silt
loam, silty clay loam, silty clay, and silt
