1. Climate Relief Vegetation SOIL FORMATION Drainage Parent Material
Study the diagram below.
Describe the influence of the various soil forming factors on the formation of a Podzol soil.
Climate
Relief
Vegetation
SOIL FORMATION
Drainage
Parent Material
Soil Biota

2. Relief Vegetation Climate SOIL FORMATION Drainage Parent Material
Cold, wet climates
Thin: Weathering is slow
Thin layer of humus: Humification is slow
A lot of Leaching and Podsolisation
Iron and Aluminium pushed down
Coniferous Forests
Needles don’t decompose easily little humification
Produce an acid humus
Northern Latitudes
Moorlands
West of Ireland
Relief
Vegetation
Climate
SOIL FORMATION
Drainage
Parent Material
Soil Biota
A Horizon often waterlogged because of impermeable iron pan that forms inbetween A and B horizon.
Weathered Slowly producing a shallow soil
Few Biota because cold climate
Therefore, little humification

3. Brown Earths
2010 Question 18
Describe and explain the characteristics of any ONE soil type studied by you

4. Mature soils have 3 distinct horizons (layers)
A Horizon – Contains topsoil, humus, vegetation not decayed, Organic Content
The most fertile part of the soil
Suffers the most leaching
B Horizon - Contains subsoil
Contains leached mineral from A horizon
C Horizon - The Regolith (recently formed soil)
Sits ontop of bedrock
Contains large particles.

5. Brown Earths Where they are found 40-60 Degrees in Northern Hemisphere
Cool Temperate Climates
Ireland-Russia in East
Scotland-Portugal in South
Most common soil in Ireland
Crumb Texture mostly
Key words
Zonal Soil
Humification
Burrowers and Mixers
Loamy
Peds – space for water
Boulder Clay from Ice age deposits
Freeze Thaw and Chemical weathering
Hydrolysis

6. Brown Earths Crumb Structure Micro-organism activity – Bacteria
Slightly acidic to slightly alkaline – it varies 5-7
What impact do the following process have on Brown Earths ?
Weathering – Mechanical/Chemical
Erosion
Leaching
Calcification
Humification
Salinisation???

7. Brown Earth Soil (10,000 years)
They form in warm climates, with mild winters and summers. South East Ireland
Found in areas that have rainfall all year. 1,600-1,800 mm per year
Found in areas of deciduous forest – Oak/Ash – Ireland's natural vegetation
Weathering is quite slow due to cool climate – What types of weathering?
Some Humification because deciduous trees shed leaves every year.
Mild climate assist decomposition
Lots of humus in these soils due to climate.
Some Leaching – because precipitation exceeds evaporation.

8. What does it look like? Quite shallow Quite thick Humus
Mild Acid Humus
Light Brown A Horizon – because
calcium, magnese
are leached out by rain
Dark Brown B Horizon – because minerals have been washed down to here (Eluviation)
Horizons often Merge
These are the main characteristics of the Brown Earth Soil.Explain why these soils have these characteristics eg. Quite shallow because of slow weathering. Which is due to the cool climate etc.

9. What does it look like?
Quite shallow - weathering is slow
Quite thick Humus – because there is
some humification
Mild Acid Humus – because
humification is slow
Light Brown A Horizon – because
calcium, magnese
are leached out by rain
Dark Brown B Horizon – because
minerals have been
illuviated here.
Horizons often Merge - biota mix the soil

11. Brown earth soils are widespread in Ireland, except in highland areas
Brown earth soils are widespread in Ireland, except in highland areas. Soil organisms, like earthworms, mix the materials together, merging the boundaries between the horizons. These soils are leached, but not heavily, so the aluminium and iron oxides are dispersed through the soil to give the overall brown colour. The original vegetation was deciduous forest, resulting in a layer of decaying leaves giving a rich humus. The deep roots of these trees reached down to the 'B' horizon (unlike coniferous trees) tapping the nutrient supply and allowing good drainage.
Climate -Precipitation greater than evaporation during summer months, resulting in only moderate leaching. Warm summers
Natural vegetations and soil organisms - mixed broad leaf, much plant litter through this is more easily broken down by more active soil biota. A moderate or moder type of humus would develop from the plant litter
Relief and drainage - downward movement of water, moderate leaching likely
Parent material - strong influence on soil development

12. They generally have three horizons: the A, B and C horizon
They generally have three horizons: the A, B and C horizon. Horizon A is usually a brownish colour, and over 20 cm in depth. It is composed of mull humus (well decomposed alkaline organic matter) and mineral matter. It is biologically active with many soil organisms and plant roots mixing the mull humus with mineral particles. As a result, the boundary between the A and B horizons can be ill defined in unploughed examples. Horizon B is mostly composed of mineral matter which has been weathered from the parent material, but it often contains inclusions of more organic material carried in by organisms, especially earthworms. It is lighter in colour than the A horizon, and is often weakly illuviated (leached). Due to limited leaching only the more soluble bases are moved down through the profile. Horizon C is made up of the parent material, which is generally permeable and non- or slightly acidic, for example clay loam.

14. Brown Earths - Characteristics
Colour
Texture
Structure
Humus Content
Water Content
PH Value

15. Brown Earths - Colour Brown due to soil formation processes
Humification is main process – Dark Brown
What is humification?
What Plant Litter creates the humus?
How does humus make its way down through the soil?
No Distinct Horizons
Burrowers/Mixers – impact of climate

16. Brown Earths - Texture How fine or coarse the soil is
Equal amts of Sand and Silt and Clay = Loamy
Loamy means space for air and water to pass through
Well Drained
Crumby structure due to rich organic content of soil and living organisms
Mild temperatures – Cool Temperate Oceanic
This helps – Burrowers and Mixers

17. Brown Earths – Humus Content
Rich due to Deciduous Vegetation
Process = Humification
Moderate rainfall – eg mm in South East of Ireland
Relief also affects the humus content – too high = less. The humus content in South East is affected by low-lying,undulating land
Mild Winters/Warm Summers – Decomposition is highest in these conditions

18. BROWN EARTHS – PH Value Refers to how acidic or alkaline the soil is
Acidic soils = low ph value
Alkaline soils = high ph value
Parent Rock generally influences the ph value
Acidic Brown Earths form on Sandstone and Alkaline Brown Earths form on Limestone
PH Values of Brown Earths encourage the activity of earthworms and Bacteria