Chapter 16 - Soil

Question 1

Define soil.

Answer 1

The top layer of the earths surface, consisting of rock and mineral particles mixed with decaying plants and animals

Question 2

What are the functions of soil?

Answer 2

Provides nutrients for plant growth

Important natural resource

Question 3

What is soil composed of?

And explain each one.

Answer 3

Mineral particles- pieces of underlying parent rock broken down by weathering and erosion to form regolith

Air- needed for plant growth and organic life

Water- dissolves minerals and nutrients to help plant growth

Living organisms- e.g. Earthworms and micro organisms help break down plant remains to form humus

Humus- dark organic matter that improves fertility

Question 4

Name three things necessary for soil formation

Answer 4

Climate
Time
People

Question 5

How does climate help soil formation?

Answer 5

• influences weathering and erosion -> parent rock broken down into mineral particles
• influences growth of vegetation which provides dead plants to form humus

Question 6

How do people influence soil formation?

Answer 6

Fertilise and drain soil to improve it

Sometimes overuse it so it becomes infertile

Question 7

How does time help soil formation?

Answer 7

It takes thousands of years to form soil suitable for agriculture

Question 8

What are the layers of soil?

Answer 8

Plant litter
A Horizon
B Horizon
C Horizon

Question 9

What is the plant litter layer composed of?

Answer 9

Decaying leaves and vegetation

Question 10

What is A horizon composed of?

Answer 10

Topsoil- dark brown/black in colour (contains humus)

Question 11

What is B horizon composed of?

Answer 11

Subsoil- lighter (less humus, more stones)

Question 12

What is C horizon composed of?

Answer 12

Parent rock

Question 13

Name four soil types in Ireland?

Answer 13

Brown earth soils
Peaty soils
Podzols
Gley soils

Question 14

What are the characteristics of brown earth soils ?

Answer 14

Dark brown
Formed in lowland areas with deciduous forest
->provided plant litter
Main Irish soil type
Fertile, suitable for arable and pastoral farming
Location: south, east, midlands of Ireland

Question 15

List the characteristics of podzols.

Answer 15

Grey
Formed in upland areas with coniferous forest
Less fertile
Suitable for forestry
Heavy rainfall causes leaching and hardpans
Location: upland areas in cork and Tyrone

Question 16

Describe the process of leaching.

Answer 16

Minerals washed down through from a to b horizon soil with rain
Makes soil less fertile

Question 17

Describe how hard pan happens.

Answer 17

Minerals washed down by leaching form crust
Impermeable (prevents water sinking through)
Causes water logging of soil
Produces wet soggy soil

Question 18

List the characteristics of tropical red soils.

Answer 18

Found near equator with hot and wet climates e.g. India and central Africa
Formed by chemical weathering

Question 19

How are tropical red soils formed?

Answer 19

Warm and wet climate produces strong tree growth
Heavy plant litter is acidic
Breaks down parent rock
Weathering of rock breaks down iron oxide (rust)
V fertile
When forests cleared leaching washes out minerals

Question 20

How does soil influence vegetation?

Answer 20

Provides nutrients
Deep soils needed for decidous trees
Shallow soils suitable for coniferous

Question 21

How does vegetation influence?

Answer 21

Plant litter provides humus
Provides cover for soil
-cutting down trees destroys cover
-vegetation gone=soil erosion 
-makes land less fertile