Introduction to Soils (Tim)

Question 1

Soil definition:

Answer 1

collection of natural bodies on earth’s surface containing living matter and supporting, or capable of supporting plants. Its upper limit is the atmosphere (air) or water, and at its lateral margins it grades to deep water or barren areas of rock and ice. Its lower limit is normally considered to be the lower limit of the common rooting zone (root zone) of the native perennial plants, a boundary that is shallow in the deserts and tundra and deep in the humid tropics.

Question 2

what is a soil profile?

Answer 2

vertical display of sopil horizons

Question 3

Pedon

Answer 3

a 3-D unit that represents the entire soil body and is the smallest volume of soil that shows all of the characteristic properties of a particular soil.
Typically represents 10-100 ft2 of surface area.

A group of pedons is called polypedons.

Question 4

soil series

Answer 4

soils that have developed from similar materials by similar processes resulting in similar appearances and properties.
The characteristic properties of a soil series are unique.
There are more than 20,000 soil series in the United States.

Question 5

soil colour

Answer 5

can suggest soil properties that may influence plants.

Dark soil near the surface may indicate a high organic matter content, which may lead to easier cultivation and higher nutrient content

(smear the soil into the notebook next to a pedon for colour)

Question 6

colour and maturity of soil

Answer 6

A young, unweathered soil may have a soil of uniform color.

In older, weathered soils, yellow and red colors may dominate well below the surface of the soil.

Question 7

Soil forming Factors

Answer 7

CL - Climate
OR - Organisms
P - Parent Material
T - Time
T – Topography

=CLORPTT (an easier way to remember the soil forming factors)

Question 8

Climate:

Answer 8

refers to rainfall and temperature.

The main effects are: weathering, the production of organic matter , and the decomposition of organic matter

Question 9

Organisms (or biotic activity

Answer 9

Vegetation is the main biotic factor.
The type of vegetation affects the soil color and organic matter content, especially in the A (or top) horizon

also- WORMS

Question 10

Grasslands vs. Forests

Answer 10

Trees contribute less organic matter to the soil each year when compared to grasslands.

Question 11

Parent Materials

Answer 11

defined as the materials underlying the soil and from which the soil developed.
There are many different parent materials, including:
Residual minerals and rocks (bedrock)
Glacial deposits
Loess deposits
Alluvial and marine deposits
Organic deposits

Question 12

Loess Deposits

Answer 12

Loess deposits formed as high speed winds picked up predominantly silt-sized particles and carried them across open areas.
As the wind speed slowed the particles fell to the ground covering the native soil and parent material.

Question 13

Alluvial Deposits

Answer 13

Alluvial deposits refer to sediments carried by and deposited in fresh water.
Flooding events carry rocks and minerals, which are deposited in bands.

Question 14

Marine Deposits

Answer 14

Marine sediments refer to sediments carried by fresh water but deposited in salt water.
Marine sediments can build up over long periods of time until eventually they are quite deep.

Question 15

Organic Deposits

Answer 15

Organic deposits originate from plants that have died or shed their leaves.
Organic deposits are common to areas such as swamps and marshes since the chemical and biological process that decompose the organic matter are greatly limited by the saturated conditions

Question 16

Time as a Soil Forming Factor

Answer 16

Time zero is the point in time at which a catastrophic event (flood or earthquake) is completed and a new cycle of soil development is initiated.
Time is important in soil formation because it determines the degree to which the other soil forming factors express themselves.

Question 17

“Old” Soils

Answer 17

“Old” soils are those that have experienced intense weathering of parent material in the presence of biotic factors. These soils will have well developed profiles containing A, E, and B horizons.

Question 18

“Young” Soils

Answer 18

Young soils have weakly developed horizons and may often lack E and B horizons.
This soil profile lacks any horizon development.

Question 19

Absolute Age

Answer 19

If the absolute age of a soil is of interest, a soil scientist may measure the activity of radioactive carbon.

Knowing the activity of the radioactive carbon the scientist can estimate the age of the parent material that has been subjected to weathering.

Question 20

Topography

Answer 20

Topography consists of three parts: elevation, slope, and aspect.
SLOPE is the tilt or inclination of the land.
ELEVATION is the height above mean sea level.
ASPECT is the direction the slope is facing.

Question 21

Soil horizons

Answer 21

are soil layers that differ from the overlying and underlying layers in some property, such as color, clay content, abundance of cracks, etc

Question 22

O Horizon

Answer 22

0 Horizon: Organic horizons are dominated by organic material.
The 0 horizons contain organic litter from plants and animals.
0 horizons are usually present on the soil surface except in the case of peats and mucks where the 0 horizon extends almost to the bottom of the soil.

Question 23

A Horizon

Answer 23

A Horizon : Mineral horizons that have formed at the soil surface or just below the 0 horizon.
The A horizon may contain some organic material mixed with mineral material.
Properties of the A horizon may reflect plowing, pasturing or similar activities.

Question 24

B Horizon

Answer 24

B Horizon: Mineral horizon that includes layers in which illuviation or accumulation of materials has taken place.
Clay, iron and aluminum oxides from the overlying E horizon have accumulated here.

Question 25

C & R Horizons

Answer 25

C Horizon: Mineral horizon consisting of unconsolidated, partially weathered material that is neither soil or rock.
The horizon is below the zone of most biological activity. The upper layer of the C horizon may become part of the B horizon as weathering continues.
R Layer: Underlying consolidated bedrock

Question 26

Transitional Horizons

Answer 26

layers of soil between two master horizons

Question 27

Transitional Horizons

Answer 27

are specific features within master horizons that are designated by lowercase letters.
There are many subordinate distinctions such as:
p – plow layer
t – accumulation of clay
b – buried layer