Introductory Soil Science

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Introductory Soil Science

• Earth Systems and Cycles
• Study Questions

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What is a system?

• A simplified version of reality
• A collection of inter-related parts that work
  together by way of some driving force
• Alternatively referred as a model
• Systems are often visualized as component blocks
  that have connections drawn between them

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Systems

• Consider the Earth System
• Systems have a structure that is defined by its
  parts and processes.
• Systems tend to function in the same way. This
  involves the inputs and outputs of material
  (energy and/or matter) that is then processed
  causing it to change in some way.
• The various parts of a system have functional as
  well as structural relationships between each
  other.
• The fact that functional relationships exist
  between the parts suggests the flow and transfer
  of some type of energy and/or matter.

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Systems

• Systems often exchange energy and/or matter
  beyond their defined boundary with the outside
  environment, and other systems, through various
  input and output processes.
• Functional relationships can only occur because
  of the presence of a driving force.
• The parts that make up a system show some degree
  of integration - in other words the parts work
  well together.

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Why do scientists devise systems when studying
natural phenomena?

• Nature is very complex so we break it down into
  smaller parts
• Sometimes these can be explained mathematically
  and through the use of graphics or box models

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Understanding Systems
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System Elements, attributes relationship

• For example the Water Cycle

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Elements, Attributes and Relationships

• Elements - are the kinds of parts (things or
  substances) that make up a system.
• rain drops, snow, clouds, rivers and lakes,
  oceans
• Attributes - are characteristics of the elements
  that may be perceived and measured.
• volume, temperature, and mass.
• Relationships - are the associations that occur
  between elements and attributes.
• Heat causes evaporation/transpiration
• Cool causes precipitation

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Water Cycle

• Reservoirs/Elements
• Ocean 97.5
• Glacial ice 1.8
• Groundwater 0.5
• Rivers Lakes 0.2
• Soil Moisture 0.005
• Atmosphere 0.0001
• NB These numbers are approximate.

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Environmental Systems

• a system where life interacts with the various
  abiotic components found in the atmosphere,
  hydrosphere, and lithosphere. Environmental
  systems also involve the capture, movement,
  storage, and use of energy. Thus, environmental
  systems are also energy systems.

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Energy Sources

• Sun
• Drives surface processes and most biological
  processes and biogeochemical cycles
• Earths internal energy
• Drives plate motion, volcanoes etc. and part of
  the rock cycle