Soil (Envs 200 4/8/10)

Front 1

What are the six components of soil?

Back 1

1. sand and gravel
2. silts and clays
3. dead organic material
4. living organisms (soil flora and fauna)
5. water
6. air pockets

Front 2

List the six soil horizons in order from top to bottom.

Back 2

O,A,E,B,C,D
(mnemonic: Orange Apes Eat Boston Creme Donuts. Yeah, I came up with that all by myself.)

Front 3

Where is the O horizon and what does it contain?

Back 3

Top level of soil.
Contains surface leaf litter and decomposing organic material.

Front 4

Where is the A horizon and what does it contain?

Back 4

2nd level of soil (counting top to bottom).
Also known as topsoil or humus. Rich in organic matter and contains lots of organisms.

Front 5

Where is the E horizon and what happens there?

Back 5

3rd level of soil (counting top to bottom).
Zone of leaching: dissolved or suspended materials move downward.

Front 6

Where is the B horizon and what does it contain?

Back 6

4th level of soil (counting top to bottom).
Also known as subsoil. Zone of accumulation: holds materials that have leached down from A and E horizons. Contains less organic material and more regolith.

Front 7

What is regolith?

Back 7

The layer of loose, heterogeneous material covering solid bedrock.

Front 8

Where is the C horizon and what does it contain?

Back 8

5th level of soil (counting from top to bottom).
Contains broken-up rock with little organic material. Partially broken-down inorganic materials.

Front 9

Where is the D horizon and what does it contain?

Back 9

Bottom level of soil.
Contains bedrock or parent rock.

Front 10

List the six properties used to characterize types of soil.

Back 10

Color, texture, structure, consistency, porosity, moisture.

Front 11

What do different soil colors indicate about the composition of soil?

Back 11

Red or yellow soil: high iron content.
Black or brown soil: high organic content.

Front 12

What is soil texture?

Back 12

The size and organization of particles.

Front 13

What is soil structure?

Back 13

The arrangement of particles in soil.

Front 14

What are some different types of soil consistency?

Back 14

wet, sticky, or dry

Front 15

What is soil porosity?

Back 15

The amount of space between grains.

Front 16

What is soil moisture?

Back 16

The presence of water in soil.

Front 17

What does a ternary diagram show?

Back 17

Soil texture and composition.

Front 18

What is soil taxonomy?

Back 18

There are 12 orders of soil taxonomy defined by the USDA. Each soil type has a different combination of features and is found in a particular climatic region.
examples: gelisols - cold climate tundra soils. andisols - formed from volcanic soils.
(we don't have to know all the individual types of soils, just the general concept of the taxonomy)

Front 19

What are some causes of environmental degradation of soil?

Back 19

1. water erosion (e.g. in Ethopia
2. wind erosion, e.g. in Somalia
3. toxic chemicals, e.g. in Uzbekistan
4. contamination from nuclear reaction explosion in Chernobyl (Sweden, Finland)

Front 20

What effect does agriculture have on soil?

Back 20

Agriculture accelerates erosion. On the map of worldwide soil degradation, there is a high correlation between soil degradation and high agricultural activity.
Poor agricultural practices in particular can accelerate erosion, such as plowing down a slope rather than across it (contour plowing).

Front 21

What is sheet erosion?

Back 21

Water flowing across a gently sloping, bare field removing a thin, uniform layer of soil.

Front 22

What is rill erosion?

Back 22

Little rivulets of running water gather together and cut small channels in the soil.

Front 23

What is gully erosion?

Back 23

Rills enlarge to form bigger channels or ravines that are too large to be removed by normal tillage operations.

Front 24

What is desertification?

Back 24

The conversion of productive land to desert by removal of vegetation and soil.