Soils

Question 1

Soil

Answer 1

The uppermost layer of the earth’s crust or lithosphere

Question 2

Pedology

Answer 2

Soil science, the study of soils

Question 3

Four components of soil:

Answer 3

• Mineral fraction
• Organic matter
• Soil air
• Soil water

Question 4

Soil Profile

Answer 4

• The vertical section of soil

- Differs in physical, chemical and organic composition and physical properties (texture, structure, colour)

Question 5

O =

Answer 5

Organic horizons

Question 6

Organic Horizons

Answer 6

Are derived from organic parent material and peat in wet ecosystems

Question 7

L =

Answer 7

Leaf litter

Question 8

F =

Answer 8

Fibric material

Question 9

H =

Answer 9

Humus

Question 10

Mineral Horizons:

Answer 10

• Ah
• Ae
• B
• C

Question 11

Ah =

Answer 11

A horizon, rich in humus, dark, and nutrient rich

Question 12

Ae =

Answer 12

A horizon, leached, grey and few nutrients

Question 13

B =

Answer 13

Modified horizon and deposits from Ae

Question 14

C =

Answer 14

Parent material and is essentially unaltered

Question 15

CLORPT

Answer 15

Climate, organisms, relief, parent material, time

Question 16

Climate:

Answer 16

The temperature and precipitation. It controls the physical and chemical weathering

Question 17

Organisms:

Answer 17

Organic matter, biotic influences

Question 18

Relief:

Answer 18

Topography, aspect and elevation

Question 19

Parent Material:

Answer 19

Composition, structure, texture acidity and nutrients

Question 20

Time:

Answer 20

Change, dynamic

Question 21

Soil forming processes:

Answer 21

1. Enrichment
2. Removal
3. Translocation
4. Transformation
5. Biological processes
6. Human Impacts

Question 22

Enrichment:

Answer 22

Material addition (mineral or organic deposition)

Question 23

Removal

Answer 23

= Losses

- Surface erosion (materials removed from LFH or A horizons) and leaching (materials dissolved in water)

Question 24

Translocation:

Answer 24

= Movement between horizons

• Eluviation
• Illuviation

Question 25

Eluviation

Answer 25

- Is the downward transport of fine particles. - Leaves sand and silt - Results in Ae horizon

Question 26

Illuviation

Answer 26

Is the accumulation of clay, humus and aluminum and iron oxides in B horizons

Question 27

Transformation

Answer 27

- Mineral alteration | - Humification (decomposition of organics into humus)

Question 28

Four main structure classes:

Answer 28

1. Granular 2. Platy 3. Blocky 4. Prismatic/columnar

Question 29

Soil colour =

Answer 29

Composition and chemistry

Question 30

Black soil =

Answer 30

Organic content

Question 31

While/pale soil =

Answer 31

Silica and aluminium oxides

Question 32

Red and yellow soils =

Answer 32

Iron oxides and minerals

Question 33

Humus =

Answer 33

Very fine organic matter and a good source of nutrients

Question 34

Air space depends on:

Answer 34

- Soil porosity | - Amount of soil water filling pores

Question 35

Soil Water

Answer 35

- Is important for plants and soil organisms | - Held in soil pores depending on the amount of water present and the size of pores

Question 36

Types of soil water:

Answer 36

- Gravitational water | - Capillary water

Question 37

Gravitational water

Answer 37

Water removed by gravity when soil is saturated

Question 38

Capillary water

Answer 38

Water that resists gravity by clinging to soil particles via capillary tension

Question 39

If we add equal amounts of water to equal volumes of a | fine versus coarse textured soil, in which soil will a plant wilt first?

Answer 39

The plant will wilt first in the fine textured soil. The fine textured soil has large surface area and small pores, and water binds to the surface with strong capillary tension. The water is more difficult for plants to extract.

Question 40

Fine textured soils:

Answer 40

Have... - High storage capacity - High capillary tension - High wilting point - Low water availability

Question 41

Coarse textures soils:

Answer 41

Have... - Low storage capacity - Low capillary tension - High water drainage - Low water availability

Question 42

Which texture class has the greatest available water capacity?

Answer 42

Loam.