Chapter 9 - Soil

Question 1

Describe the composition of soil. Include percentages

Answer 1

• Water 25%
• Air 25%
• Living organisms 2%
• Mineral matter 43%
• Humus 5%

Question 2

Describe the composition of soil mineral matter

Answer 2

This is the largest ingredient in soil. It is made up of small pieces of rocks (sand, silt, clay) broken down by weathering and erosion

Question 3

Describe the composition of soil air

Answer 3

Air fills the spaces between the soil particles. It contains oxygen and nitrogen which are essential for plants and organisms living in the soil

Question 4

Describe the composition of soil water

Answer 4

Water contains dissolved minerals. Plants absorb these minerals through their roots, helping them grow. These minerals are called nutrients

Question 5

Describe the composition of soil, living organisms

Answer 5

Earthworms, slugs, woodlice, insects and millions of microorganisms breakdown plant matter into humus

Question 6

Describe the composition of soil, humus

Answer 6

Dark, decaying organic matter. It is remains of dead creatures, plants, leaves and grass. Provides nutrients for the soil

Question 7

What is soil?

Answer 7

Soil is the thin covering of loose material that makes up the outermost layer of the planet

Question 8

What are the four soil horizons?

Answer 8

O horizon (plant litter)
A horizon (top soil)
B horizon (subsoil)
C horizon (bedrock)

Question 9

O horizon

Answer 9

Plant litter

-> Layer of vegetation

Question 10

A horizon

Answer 10

Topsoil
-> Contains humus so is dark in colour. In wet conditions, minerals in this horizon can be leached (washed downwards) to B horizon. A hardpan layer of leached material may form which is impermeable

Question 11

B horizon

Answer 11

Subsoil

->Light in colour because there is less humus. More stoney

Question 12

C horizon

Answer 12

Bedrock

-> Parent material

Question 13

What are the factors that affect the formation of soil?

Answer 13

○Climatic conditions
○Parent material
○Vegetation
○Living organisms
○Water
○Time

Question 14

What are the three types of soil textures?

Answer 14

Sandy
Clay
Loam

Question 15

Describe sandy soils

Answer 15

►Light, dry, gritty
►>70% sand -> well drained
►Drainage can cause soil to loose nutrients and suffer during drought

Question 16

Describe clay soils

Answer 16

►Heavy texture -> clay particles prevent water passing through -> waterlogging
►Difficult to plough
►Best for pastoral farming (growing grassland for animals)

Question 17

Describe loam soils

Answer 17

►Mixture of sand and clay
►Well drained
►Retain minerals
►Well aerated
►Suitable for crop farming and gardens

Question 18

Describe brown earth soils

Answer 18

• Formed in areas with deciduous forests -> lots of rotting vegetation
• Precipitation is low -> little leaching
• Dark in colour because of rich organic humus
• Creates a fertile topsoil which is good for crops
• Most common soil in Ireland

Question 19

Describe peat soils

Answer 19

• Dark
• Develop in mountain and low-lying regions with poor drainage
• These areas are waterlogged and lack oxygen
• Micro-organisms which normally break down decaying vegetation cannot exist without oxygen
• Peat consists of layers of partially rotted vegetation
• Although it is rich in humus, it is infertile because it is waterlogged
• Valuable fuel

Question 20

Describe podzol soils

Answer 20

• Developed in cold and wet areas covered in coniferous forests
• Pine needles provide little plant litter
• Heavy rain leads to leads to leaching and hardpan
• Low in humus so is relatively infertile and acidic
• Podzols are found in poorly drained upland areas of Galway and Cork

Question 21

Describe gley soils

Answer 21

• Grey in colour
• Develop where soil or bedrock beneath is impermeable, e.g. shale and clays
• Sticky and waterlogged
• Limited fertility due to poor drainage
• Used for pastoral farming

Question 22

Describe Latosols/Tropical Red Soils

Answer 22

• Red soils found in tropical climatic regions
• Is hot here all year round
• Forests around equator have high temperatures and humidity so decaying organic matter is being broken down into humus at a fast rate
• Leaching
• Within the soil all minerals are leached except iron
• The iron rusts and turns red when exposed to oxygen, giving the soil its colour

Question 23

What are the four main soil types found in Ireland?

Answer 23

1. Brown earth soils
2. Peat soils
3. Podzols
4. Gley soils

Question 24

What are the main types of soil erosion?

Answer 24

• Deforestation

* Intensive farming methods

Question 25

Deforestation

Answer 25

The cutting down and clearing away of trees and forests

Question 26

What is the solution to deforestation causing soil erosion?

Answer 26

Forest management and reaforrestation

Question 27

What is overcropping?

Answer 27

Occurs when crops are continuously grown on the land

Question 28

What is monoculture?

Answer 28

Means planting the same crop over and over again

Question 29

What is overgrazing?

Answer 29

Occurs when vegetation is exposed to intensive grazing for long periods of time or when too many animals graze on one are of land