1. Learning outcomes Soils Soil is made up of 5 main ingredients
Soil is formed by a number of factors
A soil profile consists of 3 horizons
Ireland has 4 main soil types
Soil and vegetation influence each other

2. Soil has 5 main ingredients both living and non-living
Mineral matter
Air
Water
Living Organisms
Humus

3. Mineral Matter Mineral matter is the biggest ingredient in soil
Consists of the remains of rocks that have been broken down into smaller particles by Weathering and Erosion
It includes stones, sand, silt and clay

4. Air Air fills the pores between the mineral particles
Air contains oxygen and nitrogen which are vital for the growth of plants
Air allows living organisms to survive in the soil

5. Water Water helps bind the soil particles together
Water contains dissolved minerals
Plants absorb these minerals through their roots

6. Living organisms
Soil is home to creatures such as earthworms, woodlice and slugs
It is also home to micro organisms that include bacteria and fungi
When worms burrow through the soil they mix it making it easier for water and air to pass through it
Micro organisms help breakdown dead plants in humus

7. Humus Humus is the dark, partly decayed organic matter found in soil
It is produced from the remains of dead creatures and plants
These are broken down and mixed in the soil by the living organisms
Humus provides nutrients that make the soil fertile
It also helps to bind the soil particles together

8. Junior certificate exam question

9. How soils are formed A number of factors work together to form soil
Climate
Parent material
Vegetation
Living organisms
Landscape
Time

10. Climate
Temperature and rainfall influence the rate at which parent rock is broken down by weathering
Hot climates experience chemical weathering
Cold climates experience freeze thaw

11. Parent material
The type of rock in an area also affects soil formation
Granite is slow to break down by weathering, while sandstone breaks down easily and forms soil quickly
Soils that develop from limestone are more fertile than those that develop from granite and sandstone

12. Vegetation
When vegetation dies, it is broken down and decays to add humus and nutrients to the soil
Deciduous vegetation provides mire leaf fall than coniferous vegetation

13. Living organisms
Micro organisms such as bacteria and fungi break down dead plant and animal life in the soil turning it into humus
Animals such as earthworms dig through the soil breaking it up allowing more water and air to enter it
When these creatures die, their remains add nutrients to the soil

14. Landscape
Upland areas are cold and wet so soils are often water logged
There is little plant life so there is less humus
Lowland soils are generally deeper and well drained.
They have more humus as there is a lot of plant and animal life

15. Time Time is one of the most important factors in soil formation
The longer a rock is exposed to the forces of weathering, the more it is broken down
It may take up to 400 years for 1cm of soil to form

16. Soil Profiles

17. A Horizon Also called the Topsoil
Darker than lower layers as it has a high Humus content
Most organisms live in this layer and it is the most productive layer

18. B Horizon Also called the subsoil.
Usually lighter in colour as it has less humus
More stones than A Horizon as it is closer to parent material and is protected from weathering

19. C Horizon Consists of Parent rock
Upper section may be broken in rock particles
Lower section is solid bedrock

20. Leaching

21. Leaching
The process of leaching is when excess water washes minerals from the A horizon into the B Horizon
If leaching is severe minerals such as clay and iron oxide(rust) build up at the bottom of the A horizon.
The minerals get cemented to form a impermeable crust called a Hardpan, which may cause the soil above to become waterlogged
Leaching can cause the A horizon to lose its fertility

22. Junior certificate exam question

23. There are 4 main types of soil in Ireland
Brown earth soils
Peaty soils
Podzol soils
Gley soils

24. Brown Earth Soils
Developed after the last ice age on areas formerly covered by deciduous forest
There was a plentiful supply of plant litter, which decayed to form humus giving the soil its brown colour
Rainfall is limited so there is very little leaching
Brown soils are fertile and suit a wide range of farming types
Most common in Ireland in drier lowland areas of the South, Midlands and East.

26. Podzol Soils
Developed in cold and wet areas covered by coniferous forests
Limited amount of plant litter resulting in small amounts of Humus
Heavier rainfall results in leaching causing a hard pan to develop which leaves the A Horizon with a grey colour
Relatively infertile and slightly acidic
Found in damp, poorly drained upland areas of Cork, Galway and Tipperary