Biosphere

Question 1

Explain the formation of podsol

Answer 1

-have clearly defined horizons due to a lack of mixing by soil biota
-have a black acidic mor-humus layer due to the vegetation vent difficult to break down
-have an ash grey horizon due to severe leaching or eluviation because precipitation exceeds evaporation.This washes out everything but quartz grains
-the iron and aluminium oxides collect in the ‘B’ horizon where the iron oxides can accumulate to form a thin layer of hard pan, which impales drainage and root penetration through the soil
-some iron and aluminium oxides get through the iron/hardpan, giving the ‘B’ horizon it’s dull orange colour
-are found in the upper slopes of upland areas where precipitation is heavy or where the vegetation is coniferous forest

Question 2

use a diagram to help show the formation of podsol

Answer 2

look at drawing in jotter

Question 3

explain the formation of brown earths

Answer 3

-no defined horizons due to mixing of soil by macro biota due to relatively warm and dry conditions
-have a thick, less acid and mull humus due to more easily decomposed grasses, herbs and deciduous leaves
-the A horizon has a loamy texture and is dark brown because if the high organic content
-there is some leaching but nutrients are easily replaced
-the B horizon is lighter in colour due to less humus content
-tree roots can penetrate deep into the soil which recycles nutrients
-the C horizon can be from varied parent material
-found on low lying and flatter areas of British Isles with drier/warmer climates
-extensively used for agriculture

Question 4

use a diagram to show the formation of brown earths

Answer 4

look at drawing in jotter

Question 5

explain the formation of gley soil

Answer 5

-gley soils are waterlogged which mean they are anaerobic
-in the B horizon, water logging also reduces the iron compounds in the soil turning them from normal red/brown colour to blue/grey
-can get red mottling along routes and burrows it if soil dries as oxygen changes iron compounds back to red/brown colour
-plant roots don’t penetrate deeply resulting in limited recycling of minerals back to the vegetation
-parent material vary - often glacial deposits in Scotland
-found on flat surfaces such as plateau moorland or foot of slope meaning water can’t drain away -willow, rushes, grasses
-used for rough grazing or forestry or when drained dairy and beer production

Question 6

use a diagram to show the formation of gley soil

Answer 6

look at drawing in jotter

Question 7

what are the 4 horizons in the model profile

Answer 7

1. The Ao horizon
2. The A horizon
3. The B horizon
4. The C horizon