1. Higher
Soil types

2. Podzols
These are found on a large belt across the Northern Hemisphere – associated with the coniferous forest belt or Taiga (Canada, Scandinavia, Siberia)

3. Main Features
Climate
Long, cold winters, short summers with low rainfall, but severe leaching when spring snow melts and washes down
Vegetation
Pine needles provide only a thin leaf letter and inhibit the formation of humus
The humus that is formed is very acidic
Pine needles have adapted to the conditions – pine needles reduce water loss, especially in winter and root system is shallow, to survive in frozen subsoil

4. Organisms
The cold climate discourages organisms and the soil is too acidic for earthworms
Decomposition of leaf litter is slow and definite horizons develop as there are few mixing agents
The downward movement of water, especially after snow melt leaches out iron and aluminium oxides from the A horizon
This leaves a high silica content, giving the horizon an ash grey colour
The transported iron and aluminium oxides are redeposited at the top of the B horizon
This often results in the formation of an ironpan or hardpan – this can act as an impermeable layer and lead to waterlogging

5. Podzols are generally poor soils, but they can be improved by artificial drainage and the addition of lime
Only the hardiest of crops can be grown in improved podzols

6. Podzol

7. Podzol

8. Grey Brown Forest Soils
These soils are found further south than the podzols, the Temperate Regions such as Britain and much of the rest of Western Europe

9. Main Features
Climate
There are higher temperatures and a longer growing season in this part of the world
The milder climate encourages more rapid decomposition ad as a result the humus is mild and more alkaline
Vegetation
This area is associated with deciduous forest, i.e. broad-leaved trees like the oak
The thick leaf debris from these trees returns many of the nutrients removed by the trees
This provides a plentiful supply of humus
The deep roots of the trees help mix and break up the horizons
They are able to shed their leaves in winter due to the long growing season

10. Organisms
These are very active due to higher temperatures and quickly decay the humus
Earthworms, insects and rodents mix and aerate the soil
There are more of these due to increased food supply
These soils are pedalfers (precipitation exceeds evaporation) – gradual leaching does occur and iron pans can develop where leaching is more active

11. These soils have much greater agricultural potential – soils are deep, more fertile, less acidic and better mixed. Can producer a wide range of cereal crops and good grazing land for cattle

12. Brown Earth

13. Brown Earth

14. Tundra Soils or Gleys
Found in Northern Latitudes, in areas where the subsoil remains permanently frozen (permafrost), and tundra vegetation grows in the topsoil during the brief summer.
These soils can also be found in areas that are waterlogged such as the foot of a north facing hill where water has gathered from the hillside but there is little sunshine to evaporate it. Or where parent rocks are of an impermeable type (such as mudstones, clays and any igneous rocks) impeding drainage thus forming a constantly waterlogged soil

15. Main Features
Climate
Winter temperatures range from -290C to – 400C, while summer temperatures barely reach 100C. Growing season is very short, often as short as 3 months
Vegetation
Vegetation is confined to low plants such as lichens, mosses and shrubs
Underneath the vegetation there is a black mass of very slowly decaying plant material, which is very acidic

16. Organisms
There is very little bacterial action in the very cold waterlogged conditions
When the frozen topsoil thaws at the end of the winter, the ground becomes waterlogged or gleyed (due to permafrost)
The continual seasonal freezing and thawing causes expansion and contraction, which leads to vertical mixing of the soil. This means that there are no clearly defined horizons
Tundra soils are of very limited use to man

17. Gley Soil

18. Gley Soil