lecture 8

Question 1

5 reasons soils are important

Answer 1

• Foundation of terrestrial ecosystems, influence ecosystem function
  
  • Provides nutrients, water, anchoring medium for plants
  • Influences plant sp. Composition and productivity
  • Habitat for diverse below ground community, esp. decomposers
    Ecosystem services: C storage, water filtration and storage, decomp, etc

Question 2

soil comp (rough %)

Answer 2

25% air, 25% water, 45% mineral, rest om

Question 3

5 soil horizons?

Answer 3

O (LFH)
A
B
C

Question 4

what is soil development a balance btwn

Answer 4

balance between formation and loss

Question 5

what 5 state factors influence soil development

Answer 5

○ CLIMATE
○ Topography
○ Biological activity
○ Time
Parent material

Question 6

is soil always there

Answer 6

• Soil we see isnt always there -result of dynamic processes that span geological time and short daily cycles
  BALANCE between forces that produce soils and forces that erode it

Question 7

parent material origins? what factors impact it?

Answer 7

• Parent material - origins
  ○ Granular soils - air from geological processes + production with climate
  
  • Topography is important - where it is, how it is made
    biological activity = source of organic matter in the soil = important for life

Question 8

briefly describe A- C horizons

Answer 8

• At the topLFH - organic matter, a result of things growing and falling into the soil - dark coloration due to decomp - *
  Lfh - organic horizon, active process of decomp
  
  • Organic matter and middle components interact more at A horizon, shallow roots
  • At B horizon - anything going down has to leech down from the top - lighter coloration, deeper roots,
    C - less organic material (30-40% organic material at most)

Question 9

are soil horizons the same at every biome

Answer 9

• Layers may differ in proportion in different biomes
  Rainforest - more rain = clearing of substantial amount of lower horizon

Question 10

what are soil properties strongly influenced by

Answer 10

The physical and chemical properties of rocks strongly influence soil properties

Question 11

chemical properties of soil?

Answer 11

properties
* Chemical properties:
Ph, elements, nutrient status, toxins, cations, anions

Question 12

physical properties of soil

Answer 12

• Physical properties:
  Particle size/surface area: movement and retention of water and nutrients

Question 13

how does parent material turn into soil

Answer 13

Parent material comes from earth - magma comes to the surface, forms igneous rocks then cools, weathered and broken down into sediments, weight + temp = sedimentary rocks, heat and pressure = metamorphic rocks which melt back into magma

Question 14

what two ways can parent material form soil

Answer 14

Sedentary - formed in place (consolidated)
Transported - moved from elsewhere (unconsolidated)

Question 15

describe sedentary PM

Answer 15

1. Sedentary - formed in place (consolidated)
   
   • Cumulous - organic (preserved plant residues)
     Residual (bedrock)

Question 16

describe transported P,

Answer 16

2. Transported - moved from elsewhere (unconsolidated)
   
   • Loess /eolian - wind (clay/slit/sand)
   • Till- receding glaciers
   • Alluvial/lacustrine - rivers/lakes
     Colluvial - gravity

Question 17

how do temp and moisture impact soil development?

Answer 17

○ Influence rates of physical and chemical weathering, plant growth, decomposition
○ Water and temp go up = chemical and biological processes increase
Extreme or variable temps = physical weathering goes up

Question 18

how does precip + wind and rain impact soil development

Answer 18

• Precipitation
  ○ Input of materials into systems (e.g. minerals and water)
  
  • Wind and rain- erosion and parent material formation
    Driver of soil develoment

Question 19

what impact does topography have on soil development

Answer 19

Major impact

Question 20

how does topography impact soil development?

Answer 20

• Effects via microclimate (temp and moisture); rate of biological and chemical processes (slope, aspect, exposure)
  
  • Effects via erosion and deposition; PM formation
  • Determines distribution of water on landscape (e.g. convex -> sheds water)
  • Where rocks are exposed is where weathering will take place
    Graph - lots of movement and transport of parent material depending on amount of water and slope of a particular area - steeper + water moves faster = transport material faster