1. explain the series of soils found in a soil catena.
BIOSPHERE
Summary of What You Must Know
You should be able to:
describe and explain the effect of physical factors – climate, relief, drainage, parent material, soil biota and vegetation on soil formation.
draw annotated diagrams to describe the properties of podzols, brown earth soils and gley soils, referring to horizons, colour and texture.
recognise the type of soil shown in a profile diagram, and describe the features which help to identify the soil type.
compare and contrast the appearance and soil forming factors of two of the three soil types.
explain the series of soils found in a soil catena.
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2. The Living environment
The Biosphere Core
The Living environment
This consists of plants, animals, insects, micro-organisms and people.
The Non-living environment
This consists of
Water (rain or stored in the soil).
Air – provides oxygen and carbon dioxide which is essential for life.
Solar energy – provides heat and light.
Rocks – the lithosphere – provides nutrients
Soil – varies in depth, acidity, nutrients and fertility
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3. All ecosystems depend on two basic processes:
The Biosphere – where life is found 3m below to 30m above the ground. It comprises water areas, both salt and fresh and all land.
An Ecosystem – a natural system in which life of plants and animals are clearly linked to one another and to the non-living environment through food chains.
Ecosystems vary in size from extensive areas of rainforest to a micro system under a stone.
All ecosystems depend on two basic processes:
A flow of energy (heat and light)
The recycling of nutrients within the system
Ecosystems will remain in balance unless conditions change such as climate or through human interference.
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4. Factors affecting soil formation
Soils
Soil is the function of climate (water and temperature), organisms (bacteria, insects, plants etc.), parent material (rock under the soil), relief (steepness) and time.
Factors affecting soil formation
Relief
Climate
Vegetation
Soil Formation
Drainage
Soil Biota
Parent Material
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5. A B C Soil formation – a profile Horizons Organic matter Humus
Translocation B
Hard pan C
Bed rock
Classification of soils:
When precipitation exceeds evaporation water washes down through the soils carrying minerals with it. These soils are called pedalfers and include podzols and brown earth soils.
Hard pan – a resistant layer in the soil at or below the surface. Usually caused by illuviation (deposition of minerals, humus and other materials) after leaching of the upper horizons. Hard pans can be formed of clay humus or a compound of Calcium, iron and silicon.

6. When describing any soil you must mention the impact of climate, vegetation, parent material, soil biota, drainage and relief on its development
Brown Forest Soils
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7. Natural vegetation — deciduous forest vegetation provides deep leaf litter, which is broken down rapidly in mild/warm climate providing nutrients.
Trees have roots which penetrate deep into the soil, ensuring the recycling of minerals back to the vegetation.
Moderate leaching occurs leading to a thin iron pan whenever leaching is more active. In lower rainfall areas no iron pan can form.
soil biota break down leaf litter producing mildly acidic mull humus. They also ensure the mixing of the soil, aerating it and preventing the formation of distinct layers within the soil.

8. South-facing slopes with a greater amount of sunshine and higher temperatures increase the rate of humus production.
Soil colour varies from dark brown in A horizon to lighter
brown in B horizon where humus content is less obvious. Texture is loamy and well-aerated in the A horizon but lighter in the B horizon.
The C horizon is derived from a range of parent material, with limestone producing lighter-coloured alkaline soils, clay producing dark coloured soils.
This is the most fertile of the three soils we study and it can support agriculture which allows greater human development and higher population density.

9. Podzol
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10. High levels of precipitation plus spring snowmelts leads to a great deal of water flushing through the soil causing rapid leaching of minerals and the formation of a thick iron pan.
Yellowish/ grey colour in the top soil due to leaching and a the lack of minerals from the parent material.
The Iron pan impedes drainage causing waterlogging and reduced bioactivity in the top soil.
Pine cones and needles and a lack of other vegetation result in a very thin acidic humus (mor).
Soil horizons more clearly defined as there is little mixing due to restricted action of soil biota (this is a result of the cold climate).
Cold climate also leads to slow breakdown of plant materials, thin acidic humus.

11. greater altitude results in temperatures and the growing season being reduced and an increase in precipitation. This high precipitation and short growing season restricts the bioactivity (soil biota) to a short period of the year.
Steeper slopes tend to produce thinner soils due to gravity. These steeper slopes mean more downward movement of water which increases leaching forming an iron pan.
Parent material – may be fluvioglacial sands or till or acidic parent rock which determines the nature of the C horizon

12. Tundra/Gley Soils
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13. Parent material is obvious within the B horizon.
Gleys have damp waterlogged soils due to inadequate drainage resulting from permafrost layer found below the surface. Because of this waterlogging there is a lack of oxygen in the soil.
There is a lot of partially decomposed material due to the restricted level of biotic action. This is the result of a very short summer with low temperatures and the waterlogged soils.
Horizons are poorly defined due the movement caused by constant freezing and thawing.
Parent material is obvious within the B horizon.
The vegetation is dominated by mosses and lichens which produce acidic humus.
Large areas of flat land in addition to the permafrost increase the drainage problems and form large tundra ponds in summer .
REMINDER:
When describing any soil you must mention the climate, vegetation, soil biota, relief and the impact of each on the development of the soil.

14. Soil catena showing variations in soil processes and effects along a slope
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15. Summary Notes Climate Vegetation Brown Earth Podzol Gley
Milder warmer climate leads to increased biotic activity and decomposition.
Moderate leaching occurs leading to thin iron pan in some places where leaching is more active.
High levels of precipitation and spring snow melt leads to downward movement of water and consequent leaching of minerals
Hard iron pan forms and impedes drainage.
Cold temps. result in slow breakdown of plant materials and leads to a thin black humus.
Soils are waterlogged due to inadequate drainage resulting from permafrost. Waterlogging leads to lack of oxygen in soils.
Constant freeze thaw means horizons are poorly defined and parent material is found in the B horizon.
Vegetation
A plentiful supply of plant material (esp. from deciduous leaves) leads to slightly acidic humus
Acidic humus caused by nature of the needles and cones from pine trees.
Mosses and lichens dominate vegetation leading to acidic humus

16. Bio activity (organisms)
Summary Notes
Brown Earth
Podzol
Gley
Bio activity (organisms)
Horizons merge more gradually due to increased action of biota. Leads to a thick humus and more minerals brought from the parent material.
Climate severely limits soil bio activity so horizons are clearly defined. Little influence of parent material.
Because summer is so short and cold there is a very restricted biotic action. This results in lots of partially decomposed material in the soil.
Relief and drainage
Gentle slopes lead to good drainage and restricts leaching.
Less likelihood of hard pan so soil is free draining
Higher areas have more precipitation and a shorter growing season.
Steep slopes cause downward flushing of water and increases leaching and hard pan formation.
Much flat land which increases drainage problems.

17. As they burrow through the soil, earthworms drag dead leaves and other organic matter down to the lower levels, and break them down into humus
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This earwig and her babies are among the thousands of insects and other small animals that live in soil.
Dung beetle feeding on animal dung and so help to break down plant and animal matter.

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19. Soil Slide 4 determines soil TIME HUMAN INFLUENCE
400 yrs for 10mm of soil to form
Affects soil development by
1000 yrs for 1mm in extreme conditions
Adding fertiliser
3,000 – 12,000 yrs for farming soil
Breaking up horizons by ploughing, draining or irrigating land
Horizons develop when soil reaches maturity
PARENT MATERIAL
determines soil
Accelerating or controlling soil erosion
Depth
Texture (coarse or fine)
Soil
Drainage (permeability)
Nutrient content
RELIEF/TOPOGRAPHY
Colour
Altitude: soils are thinner higher up
CLIMATE
Determines rate of weathering
Aspect: Northern Hemisphere south-facing slopes are warmer and drier.
SOIL BIOTA
Precipitation affect type of vegetation
Nutrient cycle/recycling
Bacteria and fungi decompose dead plants and animals
Dictates leaching or capillary action
Slope angle affects drainage and soil depth
Temperature determines length of growing season and humus supply
Worms and termites aerate the soil

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21. Distribution of 3 Major Soil Types: Brown Earths, Podzols and Gleys.
Arctic Circle
Gley Soil
Gley Soil
Podzol
Podzol
Brown Earth
Brown Earth
Tropic of Cancer
Equator
Tropic of Capricorn
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22. Brown Earth Profile
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23. Slide 7
Podzol Profile

24. Slide 34
Gley Soil Profile

25. Waterlogged Tundra in summer
Gley Soil Profile
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26. Which soil type is which?A B
Which soil type is which? C

27. Simplified stages in soil formation

28. HYPOTHESES: The sequence of soil profiles found in western Britain
1. Soil depth will decrease as gradient increases. 2. Soil moisture will decrease as gradient increases. 3. Soil acidity will be highest where gradient is lowest and leaching predominates.
4. Soil texture will be sandier where slope gradient is greatest and clay particles have been washed down-slope. 5. Organic content will be highest where slope gradient is lowest and soil depth greatest. 6. Soil acidity will be positively related to vegetation density.
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