Geoecology – Three Essays in Section – Choose One – Each essay 80 marks Sample Geography Paper


The Processes/Factors that influence the characteristics of soil



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The Processes/Factors that influence the characteristics of soil
Processes occurring within soils produce difference in

Texture, Structure, Colour, Ph Value etc.



Major processes are

  1. Leaching and Podzolisation

  2. Laterisation

  3. Humification

  4. Weathering



  1. Leaching and Podzolisation

    • Leaching occurs when heavy rainfall percolates down through the soil

    • Washing soluble substances down through the soils

    • Dissolving minerals and humus from the upper layers

    • Though leaching is needed to bring humus to lower layers it is often so great that the nutrients are brought so far down in soils out of the reach of roots – making soils infertile.

    • This can happen in sandy soils due to the nature of their texture as they are grainy and loosely packed,

    • Podzolisation is term that means regional leaching. That is leaching over an area

      • Can occur in areas of heavy rainfall eg. Irish Mountains

      • Can occur in areas where there is a large amount of humic acid in the soil eg under bogs or coniferous forests

      • Humic acid reacts with the rainwater making it acidic so that it dissolves most of the soil nutrients making soils infertile.




  1. Laterisation

  • Leaching in the extreme that happens in equatorial and tropical regions due to a combination of

    • Heavy Rainfall and High Temps

  • The heavy rainfall is the most important factor as it washes nutrient through the soil.

  • The high temperatures speeds up chemical reactions between water and the minerals eg. Iron in the soil from the parent rock is broken down into iron oxide or rust.

  • This iron oxide colours the soil a red and rusty colour. These soil are called Tropical Red Soils.




  1. Humification

  • Humification is the process by which nutrients are added to the soil from dead organic matter.

  • Micro organisms such as bacteria and fungi in soil break down the organic matter to a nutrient rich black gel.

  • Oxygen in the soil also breaks down organic matter into humus.

  • Rain washes the humus into the soil and the nutrients are used by the plant roots.




  1. Weathering

Weathering is a process that influences the characteristics of soil.

  • Weathering of the parent rock produces the mineral content of the soil. This is the largest component of soil.

Mechanical and Chemical weathering produce the mineral content of soil.

Chemical weathering such as carbonation causes calcium carbonate in limestone to dissolve
Question – Examine natural processes which influence soil formation. Use notes above supported by 156/157 Take three minimum processes and develop three paragraphs in your essay. Each paragraph needs to contain a minimum of six SRP’s. This is a step on the way to approaching this type of question.
Practice Run Essay Preparation
Para 1 – Process Name _____________________________
SRP 1___________________________________________________

SRP 2___________________________________________________

SRP 3___________________________________________________

SRP 4___________________________________________________

SRP 5___________________________________________________

SRP 6___________________________________________________


Para 2 – Process Name _____________________________
SRP 1___________________________________________________

SRP 2___________________________________________________

SRP 3___________________________________________________

SRP 4___________________________________________________

SRP 5___________________________________________________

SRP 6___________________________________________________

Para 3 – Process Name _____________________________
SRP 1___________________________________________________

SRP 2___________________________________________________

SRP 3___________________________________________________

SRP 4___________________________________________________

SRP 5___________________________________________________

SRP 6___________________________________________________

Just a quick reminder of what you have learnt already on this section list 4 Factors Affecting Soil Formation ________________________________________________________________________

List three Factors that influence the characteristics of soil.__________________________________

What is leaching?__________________________________________________________________

What is extreme leaching called?_______________________________________________________


By the end of today’s classes you will be another major step towards this final section of the paper. Today we are going to learn about Soil Profiles and the General Classification of Soils and how all of the components we have studied to date come together with an example of soil type





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