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esrm 210 - soils > all the rest > Flashcards

all the rest Flashcards

1
Q

5 factors affecting soil temperature

A
  1. aspect
  2. latitude / seasons
  3. vegetative cover
  4. color / albedo
  5. humus
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2
Q

only about ____% of solar energy reaches the soil

A

10

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3
Q

to increase temp. of dry soil by 1°C requires only ____

A

0.2 cal/g dry soil

(vs. 1 cal/g water)

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4
Q

cooling of soil is mostly through ______

A

evaporation

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5
Q

it takes ____ cal to evap. 1g of water;

energy comes from either ___ or from ____

A

540 cal; sun or soil

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6
Q

movement of heat energy in soils is by _______

A

conduction;

conductivity of water > soil >>>>> air

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7
Q

4 types of mulches

A
  1. clear plastic -> greenhouse effect = greatest heating effect
  2. black plastic -> absorbs heat -> radiates
  3. wood & other organic mulches: can cool soil, trap moisture
  4. permeable plastic blocks: meh
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8
Q

temp. effects of changes to soil moisture (3)

A
  1. draining in spring alows faster warming
  2. wet soils stay cooler
  3. permeable mulch slows evaporation
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9
Q

frost heaving caused by ___ ___ forming in soil and expanding ______

A

ice lenses; upwards

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10
Q

temperature effects of fire

A
  1. greatest temps at surface due to soil water lower down
  2. loss of O hzn = less insulation (so greater temp variance)
  3. water repellent layer can form due to gases a few cm deep -> erosion w/ next rain event
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11
Q

micropores are < and macropores > ___mm

A

.08

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12
Q

humus has _______ charges

A

pH-dependent

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13
Q

too much clay = ______

A

bad structure

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14
Q

CEC = ____ & ____ of _____

A

storage & availability of nutrients

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15
Q

soil water movement controlled by… (3)

A
  1. inputs
  2. soil properties
  3. energy
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16
Q

energy = _____

A

ability to do work

high conentration -> low conc. (equilibrium)

high energy -> low energy

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17
Q

potential = _____

A
  • relative ability to do work
    • relative to a reference
      • ex: pure water @ a specific height
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18
Q

Ψs = _______ = __ + __ + ___

A

soil water potential;

Ψg + Ψm + Ψo;

gravimetric + matric + osmotic

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19
Q

Ψg

A

gravimetric potential

  1. higher in soil profile = higher energy
  2. typically a positive value
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20
Q

Ψm

A

matric potential

  1. adhestion to soil particles/surfaces (+ cohesion)
  2. typically a negative value (b/c it req’s energy to break the bonds; stronger bonds = more negative
  3. @ saturation, Ψm = 0
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21
Q

Ψo

A

osmotic potential

  1. salts can behave like a particle surface
  2. typically a negative value (costs nrg to break bonds)
  3. water moves toward concentrated salt areas
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22
Q

in sandy loam, ___ dominates

in clay loam, ___ + ___

A

Ψg

Ψg + Ψm

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23
Q

-15 bars = -1.5MPa = _____

A

permanent wilting point = no water available for root uptake

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24
Q

saturation = _____ = __ dominates

A

all pores filled = Ψg dominates

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25
Q

field capacity = ___ ____ ____ = ~__ hours after saturation

A

all macropores drained = ~48 hours after saturation

26
Q

available water content = __ - ___

A

field capacity - permanent wilting point

27
Q

what enhances water storage & availability? (4)

A
  1. deeper soil
  2. barrier @ depth to water
  3. texture
  4. root access to retained water
28
Q

inputs (1) & outputs (4) to hydrologic cycle

A
  1. precipitation
  2. leaching
  3. runoff
  4. transpiration
  5. evaporation
29
Q

infiltration rate equation

A

Q / (A * T)

quantity / (area * time)

volume / (area * time)

-> depth / time

30
Q

litterfall is mostly…

A
  • water (75-95%)
  • rest is dry matter
    • 44% C
    • 40% O
    • 8% H
    • 8% others
31
Q

component of litterfall and decomposability

A
  1. 40-90% quickly decomposing….
    • sugars, starches, proteins
    • hemicellulose
    • cellulose
  2. 1-10% slowly decomposing
    • fat & waxes
  3. 5-40% slowest decomposing
    • lignin
32
Q

detrital pool = ___

A
  • undecomposed & partially decomposed litter (O hzn)
  • buildup is fx of climate, veg., organisms
    • aka production vs. breakdown/decomp
  • waterlogged + wet + cool = ++detrital pool
  • warm + humid = –detrital pool
33
Q

redox rxns produce (5) and are considered

______ _______

A
  1. CO2 + H2O + heat energy
  2. humus
  3. new microbes
  4. non-humic substances
  5. nutrients

-> incomplete decomposition

34
Q

3 parts to decomposition

A
  1. physical fragmentation (by soil fauna)
  2. leaching (of soluble components)
  3. chemical breakdown & synthesis
    • by microorgs & enzymes
    • -> formation & release of byproducts / nut’s
    • -> forms new decay-resistant components
      • humus, organic acids
35
Q

less acidic conditions favor ___

more acidic conditions favor ____

A

bacteria & earthworms

fungi

36
Q

factors affecting decomposition (9)

A
  1. aeration / water
  2. temperature
  3. pH - too high or too low = –decomp
  4. activity & availability of soil fauna & flora
  5. texture: clay binds humus, stabilizing it
    1. litter quality: –lignin = ++decomp
  7. availability of essential nut’s
    • N is most limiting; C:N ratio is key
    • C:N ration varies w/ type of litter
      • by species
      • by tissue (needles take 5 yrs, wood 150)
  8. toxic components (phytotoxins)
  9. Humans (tend to inc. decomp rates)
    • tillage, fire, slash piles
37
Q

humus is…

A

a complex mixture of brownish/blackish amorphous organic substances resulting from microbial decomp. & synthesis

  • humin
  • humic acids
  • organic acids
38
Q

non-humic compounds are…

A

identifiable; ex: oxalic acid

39
Q

benefits of humus (6)

A
  1. high surface area (retains nut’s)
  2. pH-dependant charges
  3. retains water
  4. form aggregates (adhesives)
  5. contributes to soil formation & weathering
  6. hold nutrients & energy for microbes
40
Q

muffle furnace uses ___ ____ ____ to measure %OM;

%C equation: ___

A

loss on ignition = %OM = (weight diff / initial weight) * 100

%C = %OM / 1.78

41
Q

nutrient = ___

A

element req’d for an organism’s growth & completion of its life cycle

42
Q

17/18 macro/micronutrients

A

CHOPKNS CaFe Mg B Mn CuZn Cl MoCoNi

macro: CHOPKNS CaMg
micro: Fe B Mn CuZn Cl MoCoNi

(Co only needed by legumes)

43
Q

macros needed in amounts greater than….

micros needed in amounts less than…

A

500 ppm = .05%

50 ppm = .005%

44
Q

chlorosis = ___

A

insufficient production of chlorophyll, producing yellow or yellow-white discoloration; often due to low N

45
Q

low N discoloration

A

yellow @ tips & small

46
Q

low P discoloration

A

small & purple (in older plant parts)

47
Q

low Mg discoloration

A

small, yellow -> purple gradient

48
Q

low K

A

yellow/brown tips

49
Q

low Ca

A

wilted new growth b/c Ca used in cell walls

50
Q

low Fe

A

yellow tips

51
Q

Law of the Minimum

A

level of plant production can be no greater than that allowed by the most limiting essential growth factors

52
Q

nutrient uptake rules (3)

A
  1. uptake req’s energy; plants concentrate elements
    • so uptake is fighting conc. gradients
    • energy comes from respiration
  2. _​_uptake is selective
    • plants try to exclude unwanted elements
  3. uptake is electrically balanced
    • export H+ to import cations
    • export OH- to import anions
53
Q

nutrient uptake factors (7)

A

Plant Metabolism

  1. O2 supply
  2. sunlight -> sugars
  3. temperature (both shoots & roots)

Soil

  1. water content / O2
  2. root distribution & access
  3. nutrient availability
  4. symbionts
  5. (competition)
54
Q

plant affects on soil (5)

A
  1. uptakes
  2. exudates
  3. microorganisms
  4. litter
  5. rhizosphere
    • –pH than surroundings
    • very active zone that differs from rest of soil
    • ++microbes
    • just on fine roots, mostly
55
Q

soil nutrient sources (6)

A
  1. parent materials (weathering)
  2. atmospheric deposition (dissolved in water particles)
  3. soil air
  4. secondary minerals (weathering)
  5. OM (decomp)
  6. exchange sites

availability depends on the source

soil solution >

exchange sites >

colloidal fraction (humus/clays) >

coarse fraction (primary minerals)

56
Q

3 key things to “test” for nutrient availability

A
  1. texture - tells you about storage, exch. sites
  2. humus - color & feel -> storage & availability
  3. pH - tells you what’s on exch. site & how many
    • effects solubility/availability
    • optimal range: 6-7
57
Q

nutrient movement & availability to roots (4)

A
  1. mass flow: plant takes up water, nutrients enter roots w/ water
  2. diffusion: no water mvmt; high conc. -> low conc.
    • ions -> rhizosphere -> roots
  3. plant roots grow to new areas of soil
  4. symbiants
58
Q

mobile nutrients

A
  • move readily to roots through soil
  • ++conc. in soil solution
  • ex: NO3, K, Ca, Mg
  • ++competition w/ other plants
59
Q

immobile nutrients

A
  • tend to be absorbed/precipitate out of sol’n on surface
  • complex, –conc. in solution
  • not as soluble
  • ex: PO4-3, Fe+3
  • –competition
60
Q

symbiants

A
  • mycorrhizae: symbiotic relationship b/t fungi & roots
    • very imp. for immobile nut’s
    • ecto: ext. to root cells (trees)
    • endo: penetrate root cells (grasses, crops)
  • nitrogen fixers
    • bacteria, actinomycetes
    • legume bacteria: rhizobium
    • red alder: Frankia actinomycetes
    • also by some free-living bacteria
61
Q

soil amendments

A

increase nutrient availability

  • liming: raise pH; lime (CaCO3); quicklime (CaO)
  • fertilizers: N most common, then P
    • Ammonium nitrate
    • Urea (more common in forests)
  • mixed fertilizers (N P K S)
    • problems w/ leaching / eutrophication
  • composting
    • partial rotting of plant waste to make humus
    • good compost:
      • aerobic decomp
      • moisture: 40-70%
      • piled to retain heat (50-70°C)
      • N: 1.2-1.6%

esrm 210 - soils (6 decks)

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