soil

Question 1

why is soil important (5)

Answer 1

) Foundation of ecosystem function
b) Provides nutrients, water, and anchoring medium for plants (acts as sponge to hold
moisture; substrate for holding things up)
c) Influences plant species composition and productivity (in Alberta there is more diversity
below ground than above)
d) Habitat for diverse below-ground community (eg. decomposers)
e) Filtration of water, carbon storage, decomposition, nutrient cycling

Question 2

how are soil horizons classified

Answer 2

classification based on vertical layering (soil horizons)

Question 3

O horizon?

Answer 3

O (LFH- leaf fermented humas) horizon: OM freshly
fallen at surface and partly decomposed OM deeper in
horizon
- Living vegetation that uses soil both producing and
leaving matter into the soil, leaching nutrients due to
precipitation and gravity

Question 4

A horizon?

Answer 4

A horizon: Mixture of OM, minerals, clay silt, and sand
- Distinct organic material layer
- Increase in precipitation = more distinction b/c of
more leaching

Question 5

B horizon?

Answer 5

B horizon: clay, humas, and other materials leached from
A horizon often contains plant roots
- Been leached down from the top
- Deep roots

Question 6

C horizon?

Answer 6

horizon: weathered parent material
-Less than 30% organic material

Question 7

is soil uniform?

Answer 7

Soil is not uniform matrix, it is made of minerals of different sized particles (mineral
perspective), gaps air, (movement of oxygen to roots), water, organic matter (roots,
invertebrates)

Question 8

what strongly influences soil properties?

Answer 8

The physical and chemical properties of rocks strongly influence soil properties

Question 9

what is soil development?

Answer 9

Soil development: balance between formation and loss
- Result of dynamic process: geological time and local scale
- Influenced by five state factors:

Question 10

how is PM formed?

Answer 10

-Comes from magma that is cooled into igneous rock, which is weathered to create sediment,
which through lithification it becomes sedimentary rock. Through heat and pressure can
transform into metamorphic rocks
-Recycling the crust every 200 million years by plate collision

Question 11

describe sedentary PM

Answer 11

1) Sedentary – formed in place (consolidated)
- Cumulous – organic
- Residual – bedrock

Question 12

describe transported PM

Answer 12

Transported – moved from elsewhere (unconsolidated)
- Wind – Loess/Eolian
- Receding glaciers – Till
- Rivers and lakes – Alluvial/Lacustrine
- Gravity – Colluvial

Question 13

how does climate affect soil formation?

Answer 13

-Temperature and moisture influence rates of weathering, plant growth and decomposition
-Precipitation allows the input of minerals and water, erosion, and soil formation

Question 14

how does topography affect soil formation

Answer 14

-Effects via microclimate
-Deposition from above through weather of exposed bedrock (erosion)
-Determines distribution of water on landscape by slope, aspect, and exposure

Question 15

slope impact on soil formation?

Answer 15

Steep slope (faster) = larger particles
-Steep slope (slower) = smaller particles
-Flat (slow) = deposition

Question 16

how does potential biota impact soil formation

Answer 16

-Soil stability
-Decomposition creates movement of material (tunnels by earth worms creates aeration in the
soil)
- Storing and source of organic matter (carbon)
-Modifies microclimate by slowing wind, shading, retaining moisture

Question 17

how does time impact soil formation

Answer 17

Processes can make materials non-available
-Till (glacier retreat) and eolian (wind deposited sediment) take time to develop soil

Question 18

human direct impacts on soil development

Answer 18

• Nutrient inputs (synthetic nitrogen)
• Irrigation
• Alteration of microclimate
• Increased erosional loss

Question 19

human indirect impacts on soil formation?

Answer 19

• Changes at atmospheric composition (acid rain)
• Addition and deletion of species

Question 20

what is soil function?

Answer 20

Soil function is what is added, transformed, transferred, and lost to the soil

Question 21

additions?

Answer 21

ddition:
Introduction through precipitation and winds (circulation)

Question 22

transformation?

Answer 22

-Physical weathering – breakdown of parent material with no change in chemical composition
Expansion and contraction of rocks through heating and freezing cycles or moisture
cycles
-Chemical weathering – rocks react with acid or oxidizing substances (usually w water)
-Primary to secondary minerals (primary minerals make up the parent material, secondary
minerals are what is formed in later time)
-Decomposition of organic matter, releasing carbon dioxide and nutrients (fermentation and
formation of humas)

Question 23

transfers?

Answer 23

-Movement is: lower in soil profile and moved upward (mixing, capillary action) OR high is soil
profile and moved downward (leaching)