Chapter 2 Soil Science
Except for a surface layer of plant debris, mineral soils contain less than __ % organic matter
20
Organic soils contain ____ % or more organic matter
20
A pedon is a human device for studying soil. It is section of soil 3ft x 3 ft x _______________.
5 ft
Top soil; organic matter accumulates; dark colored
A
Form below hills and mountain ranges where streams flowing down-slope deposit material in a fan shape at the base
Alluvial fan
parent materials were carried and deposited in moving fresh water to form sediments
Alluvial soil
Of the following, which is not a way climate affects soil development
Amount of sedimentary rock in parent material
Subsoil; "zone of accumulation"
B
"Parent" material of soil; little touched by soil-forming processes
C
Soil parent materials moved by sliding or rolling down a slope; scattered in hilly or mountainous areas
Collivium
Greatest eluvation; depleted in clay, chemicals, organic matter; light colored
E
Soil losses of clay, iron, and other material in downward moving water
Eluviation
Soil parent materials carried by wind
Eolian deposit
T or F: Human activity should not be called a sixth soil-formation factor
False
T or F: It is true that metamorphic rock is formed by great cold and pressure
False
T or F: Lacustrine deposits form under rapidly rushing water
False
T or F: Physical weathering is the disintegration of rock by only temperature, water, and wind
False
T or F: Slope aspect refers to degree of incline
False
Pedology is the study of soil formation, classification, and mapping. Soil formation is also known as soil __________.
Genesis
____________ rock is the basic material of the Earth's crust
Igneous
"Zone of accumulation" where chemicals leached out of the A and E horizon accumulate
Illiviation
Wholly or partially decayed plant and animal debris; undisturbed soil; example forest
O
Underlying hard bedrock; may be cracked, fractured; intrudes into soil
R
When a river cuts deeply into a floodplain to flow at a lower elevation, the old floodplain is called a _____________.
River terrace
Rock formed by pressure applied to lose materials is called ____________
Sedimentary
The three types of bedrock are igneous, metamorphic, and ___________.
Sedimentary
Deltas form when river flowing into an ocean and deposit sediments at the mouth of the river. Delta soil has very ________ particles and tends to be wet. The Mississippi River Delta of Louisiana and Rio Grande Valley of Texas and Mexico are examples
Small
Soil formation
Soil genesis
T or F: Frost wedging occurs when water freezes and expand in rocks or in cracks in the rock, causing it to break apart
True
T or F: Levees are formed along river banks where coarse materials are deposited
True
T or F: Loess soils are made up of wind-deposited silt and are important agricultural soils in much of Iowa, Illinois, and neighboring states
True
T or F: Soil formation begins with rock
True
T or F: The A, E, and B horizons make up the solum, which contains the most plant roots
True
T or F: Topography changes soil formation by changing water movement and soil temperature
True
T or F: Two important features of topography are slope and aspect
True
Organisms that can impact soil are burrowing animals, earthworms, and nitrogen- fixing _________
bacteria
minerals dissolve in water
dissolution
Flood waters spreading over large, flat areas called ______________ can leave deposits of the fine particles
floodplains
Clay, sand, rocks, and other materials that were picked up, crushed and ground, and deposited elsewhere by glaciers
glacial drift
Coarser material from glacier meltwater that was deposited near the glacier and in nearby streams and rivers
glacial outwash
Debris dropped in place to form deposits during glacier melting
glacial till
water molecules join with the crystalline structure of minerals
hydration
Minerals react with the hydrogen in water molecules and spilt the water
hydrolysis
Caliche is a hard subsoil layer cemented by _______
lime
soil genesis begins with rock breaking into smaller particles that provide the ________ materials
parent
Horizontal layers that develop as a soil age
soil horizon
A vertical section through the soil extending into unweathered parent material and exposing all the horizons
soil profile
The four soil-formation processes do not include which of the following __________
transpiration
A talus, sand, and rocks that collect at the foot of a slope, is an example of colluvial material but does not include one of the following:
waterslide
Roots growing into a crack in rock is called root ________
wedging