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