Chapter 6 - Soil

Question 1

What is soil?

Answer 1

Soil is the thin layer of loose material on the earth’s surface. It is a very important resource

Question 2

What is mineral matter?

Answer 2

The remains of rocks that have been broken down by processes of weathering and erosion. It includes sand slit and clay

Question 3

What function does air have in the soil?

Answer 3

Air fills the gaps in the soil. Air is made of nitrogen and oxygen which is essential for the growth of plants and the life of organisms in the soil

Question 4

What is the function of water in the soil?

Answer 4

Water helps to bind the soil together, distribute the minerals throughout the soil and gives life to the organisms and plants in the soil.

Question 5

What role do organisms have in the soil?

Answer 5

The soil is home to organisms such as earthworms, woodlice ect. Earthworms tunnel through the soil bringing nutrients to the different horizons as well as giving way for water to flow through the soil. Micro organisms such as bacteria and fungi break down plant litter and firm humus.

Question 6

What is humus?

Answer 6

Humus is a dark brown substance made of decayed animals and plant litter. It contributes to the fertility of the soil.

Question 7

Name 5 factors which influence soil formation.

Answer 7

1) Climate
2) Parent Material
3) Vegetation
4) Organisms
5) Landscape

Question 8

How does climate influence soil?

Answer 8

Climate influences how fast the parent material is broken down. Hot climates experience chemical weathering and cold climates experience mechanical weathering. Climate also influences the type and amount of vegetation formed.

Question 9

How does parent material influence soil formation?

Answer 9

Different kinds of rock are broken down at different rates and give the soil different levels of fertility. Granite is slow to break down, sandstone is quick to break down and limestone provides fertility to the soil.

Question 10

Explain how vegetation influences the kind and rate of soil formed.

Answer 10

Vegetation influences the amount of humus the soil has. Deciduous trees provide plentiful plant litter while coniferous trees do not.

Question 11

How to living organisms influence soil formation?

Answer 11

Micro organisms make the soil fertile by decaying the plant litter and dead animals.

Question 12

How does the landscape on which the soil forms influence the kind of soil formed?

Answer 12

Upland areas are wet and cold with little vegetation (lack of plant litter) these areas may also experience leaching and hardpan. Midlands and low lying areas experience a milder climate and thus there is lots of vegetation and plant litter.

Question 13

Give both names for each layer of soil.

Answer 13

A horizon - Topsoil
B horizon - Subsoil
C horizon - Bedrock

Question 14

What is leaching?

Answer 14

Leaching is when excess rainwater washes minerals humus and nutrients down into the B horizon causing the A horizon to loose its fertility.

Question 15

What is hardpan?

Answer 15

Hardpan is a result of severe leaching. Iron oxide builds up at between the A and B horizon and forms an impermeable layer called hardpan. Hardpan causes water logging and infertility.

Question 16

Name 4 common Irish soils.

Answer 16

• Podzol
• Brown Earth
• Gleys
• Peat

Question 17

Describe how brown earth soils form.

Answer 17

Brown earth soils formed on the bolder clays deposited after the ice age where there were many deciduous forests which meant there was lots of plant litter and micro organisms to form humus. Rainfall is limited in these areas so leaching is uncommon so these soils are very fertile and suited to arable and pastoral farming. Browns earth soils are common in Ireland and can be found in lowland areas of the South, East and Midlands.

Question 18

Describe how podzol soils form.

Answer 18

Podzol soils form in cold, wet, upland areas covered by coniferous plantations. Coniferous tress produce very little plant litter in the form of needles and so there is very little humus and the soils are infertile. Due to heavy leaching hardpan is common. Podzol soils can be found in upland Cork and Galway

Question 19

Give another name for tropical red soils.

Answer 19

Latosols

Question 20

Where are latosols found?

Answer 20

In equatorial regions

Question 21

How are red soils formed?

Answer 21

These regions experience huge amounts of chemical weathering meaning that soil forms quickly. Huge amounts of plant litter from the rainforest is broken down by micro organisms to forms lots of humus. Due to heavy rainfall these soils are commonly leached. When rain forests are cut down the soil looses its source of humus and looses fertility.

Question 22

Mention 2 ways that soil influences vegetation.

Answer 22

Fertile soils have lots of humus, oxygen, nitrogen and calcium to support a wide variety of vegetation whereas infertile soils cannot.

Deep soils can support vegetation with long roots such as the oak tree. Coniferous trees such as the pine and spruce can survive in shallow soils.

Question 23

Mention 2 ways that vegetation influences soil.

Answer 23

Vegetation binds soil particles together to slow down erosion.

Vegetation provides the plant litter necessary for humus to form. More vegetation = Fertile soils.

Question 24

Name the 5 components of soil.

Answer 24

1) Mineral Matter
2) Air
3) Water
4) Organisms
5) Humus