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ess SL > 5.1 introduction to soil systems > Flashcards

5.1 introduction to soil systems Flashcards

1
Q

how is soil a system and an ecosystem

A

system - inputs, flows, stores and outputs
ecosystem - has a living component

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2
Q

how is soil dynamic?

A

it is changing all the time:
- when wind blows it may be blown away
- water washes out nutrients - organic matter puts them back in again

etc.

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3
Q

what is the best soil for agricultures - what is it made of

A

loam
- more or less even mix of sand, silt and clay

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4
Q

different types of weathering

A
  • physical weathering (breaking rocks down into smaller particle)
  • chemical weathering
  • biological weathering
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5
Q

what is soil made up of?

A

minerals, organic matter, air and water

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6
Q

what are soil’s four primary functions?

A
  • medium for plant growth (supplies nutrients and water)
  • major water storage and purification system
  • provides a habitat for organisms
  • modifies the atmosphere through respiration of the soil organisms and plant roots
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7
Q

what factors affect the characteristics of soil?

A
  • climate
  • organisms
  • parent material
  • time
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8
Q

how can climate effect soil characteristics?

A

precipitation/evaporation balance which determines the dominant direction of water movement

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9
Q

how can organisms effect soil characteristics?

A

soil organisms break down the dead organic matter and mix it into the upper layers of the soil

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10
Q

how can time effect soil characteristics?

A

the development of soil is a long and slow process - so it is considered a non-renewable natural capital - different stages of formation of soil can lead to different characteristics

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11
Q

definition of ecosystem

A

Ecosystem is a community of interdependent organisms and the physical environment they interact with. A community is a group of populations living and interacting with each other in a common habitat.

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12
Q

how is soil an ecosystem?

A

qualities that ecosystem and soil share:
- biotic factors interacting with abiotic factors
- biodiversity
- system: inputs, outputs, stores, flows
- transfers and transformations
- open system (energy and matter are exchanged)
- many species
- food web

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13
Q

what are some biotic elements of soil?

A
  • mico-organisms (bacteria, algae and fungi)
  • macro-organisms (earthworms, insects, mites, mammals etc.)
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14
Q

how do decomposers contribute to soil?

A

it creates plant nutrients and microbial remains - this binds the soil and gives it its crumb structure

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15
Q

what are inputs of soil?

A
  • minerals
  • organic matter
  • gases
  • water
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16
Q

elaborate on minerals as an input of soil

A
  • comes from weathering of the parent material
  • weathering: through physical, chemical and biological processes
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17
Q

elaborate on organic matter as an input of soil

A
  • living organisms that are on and in the soil
  • during succession early plants die - add organic material to the soil
  • they add organic material to the soil and carry out some of the soil forming processes
18
Q

elaborate on gases as an input of soil

A
  • certain plants fix atmospheric nitrogen and change it into nitrates
  • nitrogen fixation - forms an input into the soil system
  • oxygen is removed and carbon dioxide is added to the soil
19
Q

elaborate on water as an input of soil

A

precipitation

20
Q

what are stores of soil

A
  • organic matter
  • organisms
  • minerals
  • air
  • water
  • nutrients
21
Q

elaborate on organic matter as a store of soil

A

DOM - dead organic matter
- anything that once lived in an ecosystem becomes the organic matter store in the soil
- a store of nutrients that can be taken up by the plants to be used for growth

22
Q

elaborate on organisms as a store of soil

A
  • organisms add nutrients to soil when they deposit waste
  • remove oxygen and add carbon dioxide to break down dead organic matter
23
Q

what are the outputs of soil

A
  • organic matter
  • water
    (water leaches minerals from soil)
  • gases
  • wind physically removing soil by blowing it away
24
Q

what are some processes, transfers and transformations?

A
  • leaching and evaporation
    (dry places - evaporation levels are high)
    (leaching - nutrients are leached out of soil)
  • decomposition
    (break down dead organic matter - release the plant nutrients)
  • weathering
    (breakdown of parent material adds minerals to the soil)
25
Q

what is a soil profile

A

a vertical section through a soil, from the surface down to the parent material, revealing the soil layers or horizons

26
Q

what are the four main horizons of soil

A
  • O
  • A
  • E
  • B
  • C
27
Q

whats O horizon

A

organic horizon

  • includes all DOM accumulated on top of soil
28
Q

what is A horizon

A

top soil - mineral layer

  • highest zone of biological activity
  • high organic content
29
Q

what is E horizon

A

eluvial/leached horizon
- leaching removes material from the horizon

30
Q

what is B horizon

A

illuvial or deposited horizon

31
Q

what is C horizon

A

bedrock or parent material

32
Q

what is soil texture

A

the proportion/percentage of mineral particles sand, silt and clay of different sizes within soil

33
Q

info about sand particles

A

largest particles
- 0.5mm-2mm
- allows water to flow in due to gaps in particles
- easy to dry out - not easily flood

34
Q

info about silt particles

A

middle size particles
- less than 0.02mm

35
Q

info about clay particles

A

smallest particles
- 0.002mm
- does not allow water to flow through
- cant dry out - can flood

36
Q

loam soil

A
  • has a balance of particle size
  • provides balance of nutrients and air space
  • best for primary productivity
  • more niches
  • higher biodiversity
  • complex food webs
  • resilience
37
Q

what is field capacity

A

the max amount of water that a soil can hold

38
Q

what are some soil conditions that are important for plant growth?

A

biota
- organisms within soil
water retention
- how well soil holds onto the moisture
aeration
- infiltration - how water/air can come in and out

39
Q

what is the function of soil for humans

A
  • medium for plant growth (most food for humans is grown in soil)
  • soils contain an important store of relatively accessible freshwater (approx. 0.005% of global freshwater)
  • soils filter materials added to the soil thereby maintaining water quality
  • some recycling of nutrients takes place in soil → breakdown of dead organic matter
  • acts as habitat for billions of microorganisms as well as for some larger animals
  • provide raw materials in the form of peat, clays, sands, gravels, and minerals
40
Q

is soil renewable or non-renewable

A

non-renewable
- it takes so long to develop and the current rate of resource use compared to the length of time required for resources to be replaced

41
Q

what kind of systems are soils

A

open system in a steady state equilibrium

42
Q

what has an effect on soil structure

A
  • presence of organic matter and soil organisms

materials excreted by soil organisms bind the soil together to form lumps

ess SL (4 decks)

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