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lec 10 soils Flashcards

1
Q

why learn about soil?

A

-allows to make better decisions on plant materials

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2
Q

– “ of soil has been created since the glaciation

A

8-10 “

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3
Q

what is soil/ earth

A

-material that constitutes the outermost solid layer of the planet

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4
Q

what is def’n of soil?

A

naturally occurring mixture of inorganic and organic ingredients with a definite form, structure and composition

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5
Q

what is average soil ingredients?

A

45% mineral matter
25% water
25% air
5% organic matter or humus

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6
Q

why are compacted soil bad?

A

removes air space which removes air space giving less ability for organic matter to live

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7
Q

how is soil formed

A

by interaction of the earth’s crust with atm and biological influences through combination of 5 factors

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8
Q

what are 5 soil forming factors

A
  1. parent material
  2. regional climate
  3. topography
  4. biotic potential
  5. time
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9
Q

what is parent material

A

earth material; both mineral and organic

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10
Q

describe role of regional climate in soil formation

A

parent material is broken down into finer particles via weathering- controlled by climate of location
-temp and water major climatic forces

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11
Q

describe topography

A

-hilliness, flatness or amount of slope of the land

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12
Q

describe biotic potential/ organisms in formation of soil

A

-plants and animals help create soil via decomposition and disturbance via digging

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13
Q

t or f; true soil is a mass of mineral particles

A

false; influenced, modified, and supplemented by living organisms

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14
Q

what is humus

A
  • semi- soluble chemical (biochemical) substance

- produced via decomposition of organic matter into by fungi and bacteria

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15
Q

what do soil organisms such as earthworms, beetles and termites do for soil ?

A

vertically redistribute humus within the mineral matter found beneath surface of soil

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16
Q

what are 3 benefits of humus

A
  1. enhances a soils ability to hold and store moisture
  2. primary source of carbon and nitrogen req’d by plants
  3. improves soil structure
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17
Q

what are the layers of soil called . why are they formed

A
  • horizons
  • integrated effects of climate and biosphere change
  • becomes less pronounced with depth
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18
Q

what is a soil profile?

A

-vertical cross- section view of soil

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19
Q

what 4 horizons are noted in soil profile ?

A
  1. o= organic
  2. a= topsoil
  3. b= subsoil
  4. c= parent material
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20
Q

what does the organic layer consist of

A

-fragments of leaf litter, twigs, roots, and other organic material lying on surface of soil at various levels of decomposition and humus

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21
Q

t or f; organic layer is not present in cultivated fields

A

true

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22
Q

what is found in the topsoil layer ?

A
  • humus and other organic material mixed with mineral particles
  • zone of translocation which illluviation has removed finer particles and soluble substances to a lower layer
  • dark in colour, light texture and porous
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23
Q

what is the most productive soil layer?

24
Q

what are characteristics of subsoil?

A
  • light coloured, dense and low organic matter
  • strongly influenced by illuviation ; receives materials from A
  • may be coloured by oxides of irons and aluminum or by calcium carbonate
25
describe the parent material layer
unconsolidated organic and mineral in which soil forms | -largely uninfluenced
26
what layer would you find bedrock? what is bedrock?
c= parent material | -solid rock underlies soil and other unconsolidated material
27
what is the easiest way to characterize soil?
-physical characteristics : colour and texture
28
what are 3 categories of colour in soil
dark, mod dark and light
29
how is soil texture characterized?
-expressed in terms of % sand, silt and clay
30
how many textural classes are there?
12
31
describe texture characteristics of sand
- 3D, round, gritty - large particles= more drainage - dif to retain water
32
describe texture characteristics of silt
- 3d, round floury texture - smaller particle - increased retention, less drainage
33
describe texture characteristics of clay
- small flat particle form impenetrable plates | - min drainage, dif aeration
34
what does texture of soil refer to
- size distribution of mineral particles found in sample
35
what is the most important mineral particle found in soil? and why?
clay ; highly reactive, ability to attract and hold positively charged nutrient ions
36
what are aggregates
grouping of soil particles into porous compounds
37
t ir f; soil structure is stable
false; aggregates can be destroyed by tiliage, compaction and depletion
38
how can aggregates be destroyed
tillage, compaction, depletion of sol organic matter
39
t or f, poor soil structure in creases total porosity
false; good structure increase porosity because large pours b/ween aggregates= better root penetration and air and water movement
40
what pH is considered acidic? alkaline ?
6-1; 8-12
41
t or f; soil pH can influence plant growth, quantity activity and types of microorganisms
true
42
t or f soil ph does not impact nutrient transformations and solubility of essential nutrients available to plants
false
43
what essential micronutrient is available in slightly acidic- slightly alkaline soil?
phosphorus
44
essential micronutrients become more available with ___ ph
decreasing ( more acidic)
45
at what pH level can essential micronutrient become available to a point of toxicity in plants? what essential micronutrients do these include?
<5.5; Al, Mn, Fe
46
what are important mediators on nutrient exchange systems? where are they most active?
bacteria, slightly acidic- slightly alkaline
47
what are On soils mostly containing?
- calcareous; limestone parents rock material | - higher Ca= higher pH
48
what is the main problem with 'designer soils'
- contain too much organic matter | - can't be sustained naturally over time decomposes an d settles
49
what are mycorrhiza?
symbiotic relationship b/ween fungus and root
50
t or f; soil fumigants, excess fertilizer, excessive irrigation, poorly drained soil inhibit mycorrhizae activity
true
51
name 7 things that encourage mycorrhizal activity
1. coarse woody mulch 2. consv. additions of N fertilizer 3. warm temp 4. mild drought/ nutrient deficiency 5. reduced pesticide 6. reduced aoil disruption - increase plant diversity
52
what are the top 3 ways to improve soil conditions
1. cover cropping 2. muching 3. composting
53
__% of landfill waste is food waste
20
54
what happens when food decomposes? why is this an issue?
-release of methane gas, heat up earth 20 times faster than CO2
55
what is vermicomposting?
- ' cold composting' - lower carbon to nitrogen ratio - uses worms to compost

ECOL 1001 (8 decks)

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