Chapter 16 - Soil Flashcards
Define soil.
The top layer of the earths surface, consisting of rock and mineral particles mixed with decaying plants and animals
What are the functions of soil?
Provides nutrients for plant growth
Important natural resource
What is soil composed of?
And explain each one.
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
Name three things necessary for soil formation
Climate
Time
People
How does climate help soil formation?
- influences weathering and erosion -> parent rock broken down into mineral particles
- influences growth of vegetation which provides dead plants to form humus
How do people influence soil formation?
Fertilise and drain soil to improve it
Sometimes overuse it so it becomes infertile
How does time help soil formation?
It takes thousands of years to form soil suitable for agriculture
What are the layers of soil?
Plant litter
A Horizon
B Horizon
C Horizon
What is the plant litter layer composed of?
Decaying leaves and vegetation
What is A horizon composed of?
Topsoil- dark brown/black in colour (contains humus)
What is B horizon composed of?
Subsoil- lighter (less humus, more stones)
What is C horizon composed of?
Parent rock
Name four soil types in Ireland?
Brown earth soils
Peaty soils
Podzols
Gley soils
What are the characteristics of brown earth soils ?
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
List the characteristics of podzols.
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
Describe the process of leaching.
Minerals washed down through from a to b horizon soil with rain
Makes soil less fertile
Describe how hard pan happens.
Minerals washed down by leaching form crust
Impermeable (prevents water sinking through)
Causes water logging of soil
Produces wet soggy soil
List the characteristics of tropical red soils.
Found near equator with hot and wet climates e.g. India and central Africa
Formed by chemical weathering
How are tropical red soils formed?
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
How does soil influence vegetation?
Provides nutrients
Deep soils needed for decidous trees
Shallow soils suitable for coniferous
How does vegetation influence?
Plant litter provides humus Provides cover for soil -cutting down trees destroys cover -vegetation gone=soil erosion -makes land less fertile
