Biosphere Flashcards
Soil Forming Factors
Parent material
-material from which the soil is formed
- consolidated/ unconsolidated
- hard rock takes longer to weather( broken down) to form smaller particles of sand/clay/silt which make up soils
HARD ROCKS- granite/ schist
SOFT ROCKS - shale/ sandstone
Soil forming factors
Climate
- temperature can effect the rate at which erosion occurs( freeze thaw)
- lots of rain can effect the rate of chemical weathering( increases)
- can effect the amount of biota)
EVAPORATION>PRECIPITATION
- more evaporation =water being drawn up from underground layers = CAPILLARY ACTION
PRECIPITATION>EVAPORATION
-higher rain levels= water will percolate downwards through the soil= leaching
Soil forming factors
Biota
Boots are living organisms such as plants, microbes and soil animals
Soils are broken down quicker by the presence of biota as they MIX and add NUTRIENTS to the soil
Soil forming factors
Relief
Slope steepness, shape and length of slip are important- they influence the rate at which water flows into or off the soil
- soil on slopes is more susceptible to erosion
- aspects also influences the angle at which the sun’s rays hit the earth’s surface EG in the northern hemisphere cooler north facing slopes are usually forested with slower soil development than on warmer south facing grasslands.
Greater altitude results in lower temperatures and the growing season being reduced and an increase in precipitation. which slows down formation
Soil forming factors
Drainage
well drained soils have more pore space, so allow for the movement of minerals/ materials which helps with the development of soils
Soil forming factors
Time
all soils start as parent material.
- longer timescales allow for more erosion of this parent material and the accumulation of organic matter, but also means that wore leaching is possible
- soil formation processes are continuous, meaning that floods can deposit new material, which covers the previous soil surface and cause underlying horizons to become buried.
Podzol soil profile
O- thick layer of mor humus (pine needles)
Ah- stained darker from illuviation of humus/ no mixing due to lack of biota
E- water logging and gelling may occur GREY
iron pan
B- accumulation of clays stained by iron oxides RED/ORANGE
Gley soil profile
O-thin mor humus
Ah-build up of organic matter
BgEvidence of gleying sometimes waterlogged orange dots
Cg-always waterlogged
Brown earth soil profile-
Oa- thick, wee decomposed mull humus/ lots of biota
Ah- dark coloured
AB- no defined boundary(leaching in wetter months, capillary action in warmer)
distinctive brown/red colour
C permeable/free draining/ unconsolidated rock
Podzol soil forming factors
PARENT MATERIAL acid rock(usually granite/schist) CLIMATE cool with high precipitation BIOTA slow organic breakdown limited mixing RELIEF varies from sea level to mountains
Gley soil forming factors
PARENT MATERIAL costal sands or glacial till CLIMATE relatively mild high precipitation BIOTA anaerobic organisms found RELIEF where ground water is high with an impermeable layer below
Brown earth forming factors
PARENT MATERIAL permeable non/slightly acidic CLIMATE mild/warm with moderate rainfall BIOTA broadleaf woodland mull humus many earthworms and other mixers RELIEF generally low lying
Key features of a gley soil
- poorly drained
- periodic or permanently waterlogged
- well defined layers
- gleying and orange coloured mottling in sub soil
- horizons generally rich in organic matter
Key features of a podzol soil
- extensive group of leached, acidic soils
- free draining
- well defined layers
- coniferous woodland/heather moorland
- low litter in nutrients
- little biological activity
- mor humus
Key features of a brown earth soil
- free draining
- well mixed/undefined layers
- deciduous woodland
- litter rich in nutrients
- lots of biological activity
- Mull humus
