Biosphere

Question 1

Podzols

Answer 1

Vegetation is short rooted which means that the layers are separated. Rapid leaching of iron and aluminium oxides start to create the brown layer. The leaching continues downwards and makes the grey layer below. The grey layer has an iron pan and this stops drainage. The reddish brown layer has a rough texture and it also has aluminium oxide in it. Parent rock is acidic. The organisms keep nutrients in the soil and the organisms do not mix with other layers.

Question 2

Brown Earth

Answer 2

Natural vegetation - deciduous forest vegetation provides deep leaf litter, which is broken down rapidly in mild /warm climates. Trees have long roots which penetrate deep into the soil assessing nutrients from lower layers which are recycled to leaves. Soil - organisms - they ensure the mixing soil, aerating it and preventing the formation of distinct layers within the soil. Climate - precipitation slightly exceeds evaporation, giving downward leaching of the most soluble minerals and the possibility of iron pan forming, impeding danger.

Question 3

Tundra Gley

Answer 3

Cool to cold temperatures lead to a very slow rate of decomposition of organic matter creating a thin humus.

Plant roots do not penetrate deeply resulting in limited recycling of minerals back to the vegetation.

Anaerobic conditions means few organisms living in soil to burrow and tunnel through the soil.
The organisms left in the soil extract the oxygen they need to survive from the iron compounds and the soil gradually turns grey, blue or green as the oxygen is depleted.
Soil has a blue grey colour due anaerobic conditions.
The iron compounds are changed from red brown to blue due to oxygen being extracted by microorganisms.
Red mottling in small air pockets due to re-oxygenation of the iron in the soil due to burrowing animals/soil drying out in summer.
Impermeable clay impedes drainage and causes waterlogging.