Lecture 10: Chapter 19- Soil Classification

Question 1

pedon

Answer 1

the smallest sampling unit of soil that displays the full range of characteristics (1-10 m^2)

Question 2

polypedon

Answer 2

made up of pedons with similar properties

Question 3

epipedon

Answer 3

a horizon that forms at or near the SURFACE and in which most of the rock structure has been destroyed (darkened)

Question 4

describe the classification criteria of soil taxonomy for soil orders and suborders

Answer 4

soils are named by the presence/absence of diagnostic surface horizons (epipedons) and/or subsurface horizons

Question 5

moisture regime: aquic

Answer 5

-soil is saturated with water
-virtually free of gaseous oxygen for sufficient periods of time
-evidence of poor aeration (gleying and mottling)
-common in wetlands

Question 6

epipedon: anthropic (A)

Answer 6

-human transported or modified materials like glass
-can have puddled condition (rice paddies)

Question 7

epipedon: folistic (O)

Answer 7

-organic horizon saturated for less than 30 days per normal year
-more or less freely drained horizon that formed in organic material

Question 8

epipedon: histic (O)*

Answer 8

-a 20-60 cm thick layer of ORGANIC SOIL MATERIALS (peat or muck) overlying mineral soil
-formed in wet areas
-black to dark brown color
-very low density
-saturated horizon

Question 9

epipedon: melanic (A)*

Answer 9

-thick, black, high in organic matter (>6% organic carbon)
-common in volcanic ash soils

Question 10

epipedon: mollic (A)*

Answer 10

-thick (generally >25 cm)
-dark colored
-high base saturation
-well developed structure
-most common in grassland soils

Question 11

epipedon: ochric (A)*

Answer 11

-lighter in color
-lower in organic matter or thinner than a mollic
-may be hard and massive when dry

Question 12

epipedon: plaggen (A)

Answer 12

-human made sod-like horizon created by years of manuring
-often with artifacts and spade marks

Question 13

epipedon: umbric (A)*

Answer 13

similar to mollic except low base saturation

Question 14

moisture regime: udic

Answer 14

-soil moisture is sufficiently high year round in most years to meet plant requirement
-common in humid regions

Question 15

moisture regime: ustic

Answer 15

-soil moisture is intermediate between udic and aridic regimes
-generally plant available moisture during the growing season
-severe periods of drought may occur
-common in semi arid regions

Question 16

moisture regime: aridic

Answer 16

-soil is dry for at least half of the growing season
-moist for less than 90 consecutive days
-common in arid (desert-like) regions

Question 17

moisture regime: xeric

Answer 17

-found in mediterranean-type climates
-cool, moist winters and warm, dry summers
-long periods of drought in the summer

Question 18

alfisols

Answer 18

alf
well developed

Question 19

andisols

Answer 19

and
organic

Question 20

aridisols

Answer 20

id
desert, rocky, not a lot of vegetation, need stable land surface

Question 21

entisols

Answer 21

ent

Question 22

gelisols

Answer 22

el
tundra frozen below 1m
soil needs to be frozen for at least 2 years

Question 23

histosols

Answer 23

ist
no particular climate just organic

Question 24

inceptisols

Answer 24

ept
baby soils
pretty common in temperate areas

Question 25

mollisols

Answer 25

oll
arid

Question 26

oxisols

Answer 26

ox
inner tropics
continuous tropical climate

Question 27

spodosols

Answer 27

od

Question 28

ultisols

Answer 28

ult
ULTIMATE soil because they take so much time
lots of weathering so need warm and humid climate
stable land surface
common in south east like florida
no glaciers!

Question 29

vertisols

Answer 29

ert
super rich in clay
interesting patterns because they shrink and swell