Soil formation and chemistry Flashcards
Why is soil important? (general areas)
Climate
Ecosystem
Pollutants
Water
Health
Plants
Why is soil important for ecosystems?
hold 1/4 of the worlds biodiversity
Why is soil important for dealing with pollutants?
water filtration system
What can be present in one teaspoon of soil?
1 billion organisms
10,000 species
10 kilometres of fungi
Why is soil important for plants?
95% food production (CWR)
Building materials
Clothes
Why is soil important for water?
400mm can be stored in 1m
1.5 Olympic swimming pools per hectare
60% water return
What is soil composition by volume?
45% mineral
5% organic
50% space (air/water)
What is soil composition by mass?
0% air
18% water
80% mineral
2% organic
What 5 things is soil formed by?
Parent material
Climate
Topography
Time
Biological
How is soil formation affected by parent material?
original weathered bedrock transported from elsewhere, usually by wind or water
How is soil formation affected by climate?
amount, intensity, timing and type of precipitation that degrades ecosystem into soil
How is soil formation affected by topography?
slope and aspect affect the angle of the land and position toward/away from the sun that soil will be exposed to
How can time affect soil formation?
the amount of time it takes for four factors to interact with each other
How can biological factors affect soil formation?
Plants, animals, microscopic organisms, and humans interact with soil in different ways
What is pedigenesis?
process of soil formation
What 2 ways can pedigenesis be?
ex-situ
in-situ
What is ex-situ pedigenesis?
gravity downslope
Colluvial
What is colluvium?
loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rain-wash, sheet-wash, slow continuous downslope creep
What is ex-situ pedigenesis?
transported and deposited material
What would earths early soil have been like?
simple structure
poor at holding water
lack of nutrients or soil biota
What is the progression to form present day soil?
Not much for first few bn yrs
Stramatalites (first algae/ cyanobacteria)
Mosses (465 Ma)
Proper soil development with biota (420-400Ma)
Lichens
Vascular plants (DOM)
What did the development of lichens allow for?
rock to be broken down so nutrient cycling
What are some key parent materials?
Granite (acidic)
Basalt (basic)
Sandstone
Mudstone and shale (clay material)
What will soil be like in an area with active glaciation?
No soil due to scouring of rock by overlying ice
What are the 2 main soil groups?
Organic
Mineral
How can you tell the organic layer in soil?
Dark black layer in the soil
What are the characteristics of organic soil?
Saturated soil or low temp
Low nutrient level
Low pH
High rainfall
Why is organic matter content so high in organic soils?
As the conditions aren’t favourable for decomposition and detritivores
What is the organic matter content cut-off for organic soils?
> 30%
What is alluvium?
loose unconsolidated soil or sediment which has been eroded and reshaped by water and then deposited
What is eluvium?
weathered material at or near the source
What are Lacustrine deposits?
Clay deposits originally at bottom of lake but the lake in no longer there
What is till?
unconsolidated material deposited by glacial ice
What is ablation till?
Till that falls onto the top of the glacier from surroundings so doesn’t experience any or little erosional processes
What is basal till?
rounded sub-glacial material that is heavily eroded due being dragged along bedrock
What is outwash?
Unconsolidated, sorted material deposited by meltwater from a glacier
What is an outwash plain?
Accumulation of sediment in front of a end moraine
flat consisting of sand and fine sediments
What will marine deposits be like?
Shell, reef and other bits previously at bottom of ocean which has been uplifted
What is eolian deposits?
Volcanic ash
What is podzol?
A type of soil with string leaching leading to a poor top soil
What are peaty soils important for?
Carbon storage
What is leaf litter?
Matter which isnt decomposing:
Leaves, needles, twigs, moss etc