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Lecture 7 Flashcards

1
Q

who is Will Allen?

A

movie Fresh

In 1993 purchase a derelict plant nursery “Growing Power” on the north side of Milwaukee – last functional farm within Milwaukee city limits

Received awards for role promoting local food security and urban agriculture

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2
Q

what were the 2 exs of high tech gardening?

A

God’s Acres - all year vegetables

vertical farming indoors - very high tech

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3
Q

what do plants require for growth?

A

light within optimum wavelengths

appropriate temps

nutrients

water

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4
Q

what are factors affecting soil formation?

A

parental material

climate

plant & animal life

geography

time

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5
Q

soil formation is a ____ process

A

geological

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6
Q

what does an undisturbed vegetative soil consist of?

A

several soil layers or “horizons”

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7
Q

what are the soil layers or “horizons” of soil?

A

O - oxygen

A- topsoil

B- subsoil

C - parent material

R - bedrock

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8
Q

describe the subsoil

A

zone of accumulation

Lower in organic matter than the A horizon

Roots penetrate

Accumulation of clay, calcium carbonates,
mineral oxides

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9
Q

describe the parent material layer of soil

A

coarsely weathered material, low organic matter

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10
Q

describe the bedrock layer of soil

A

base material from which the soil was formed

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11
Q

how are soils modified by human activities?

A

addition of fertilizers, organic materials & pesticides

cultivation

vegetation

drainage

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12
Q

what are the physical properties of soil? (8)

A

texture

structure

porosity

bulk density

colour

temp

aeration status

water relations

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13
Q

what does a typical mineral soil consist of?

A

25% air

25% water

45% mineral

5% organic matter

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14
Q

what determines soil texture

A

Proportion of sand, silt and clay particles in the soil

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15
Q

list the particles from smallest to largest

A

clay

silt

sand

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16
Q

soil texture is the relationship b/w ___ & ___

A

SA & volume

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17
Q

what does particle size effect?

A

drainage

water holding capacity

aeration

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18
Q

Adhesion of _____ to soil particles

A

water

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19
Q

soil has a reactive SA for _____ _____ ____

A

carbon exchange capacity/(CEC)

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20
Q

where do the soil microbes reside?

A

soil particles

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21
Q

the more SA of soil particles = ______ water retention

A

more

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22
Q

what soil texture has the highest cation exchange capacity? & why?

A

clay

more SA

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23
Q

why is it desirable to have an even mixture b/w all soil particles?

A

desirable balance of:

workability

water holding capacity

& nutrient holding ability loams (L)

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24
Q

what soil texture has the lowest cation exchange capacity?

A

sand

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25
what soil texture has the lowest drainage?
clay
26
what soil texture has the highest drainage?
sand
27
what soil texture has the lowest water holding capacity?
sand
28
what soil texture has the highest water holding capacity?
clay
29
what soil texture has the lowest aeration?
clay
30
what soil texture has the highest aeration?
sand
31
loams (L)
medium textured soils made up of a mixture of sand, silt & clay and are considered to be “ideal”
32
cation exchange capacity (CEC)
index of soil fertility
33
are many essential plant nutrients anions or cations?
cations
34
incres SA = ______ CEC
higher
35
why is a high CEC desirable?
can attract & hold nutrients & make them available to plants
36
soil structure
the form & degree of aggregation of soil mineral particles
37
Soil primary particles are arranged into secondary particles known as ______ or _____
peds or aggregations
38
how do peds or aggregations vary?
Size & shape
39
what compounds act as cementing agents that form aggregates?
Clay, organic matter & other compounds
40
what factors does soil structure effect? (4)
pore size water holding capacity infiltration rates permeability of water and air
41
what does poor soil structure (low aggregation) effect?
root penetration reduces plant vigor
42
soil moisture availability is dependent on what 2 factors?
soil texture & structure
43
how does the water availability change when moving from sand to clay? why?
more water attached to the particles clay particles are smaller
44
what draws water down through the soil?
gravity
45
what force attracts water molecules to each other?
cohesion
46
what force attracts water to the surface of the soil particles?
adhesion
47
water experiencing cohesion is ______ available to plants
highly
48
water experiencing adhesion is ______ available to plants
largely not
49
what are the materials forming soil aggregates? (6)
fungal hyphae roots microbes humus clay inorganic materials (minerals)
50
humus
organic material but is very degraded that is no longer seen as organic mater, dark coloured
51
macropores
> 75 um water will drain freely at saturation. Increases aeration, root penetration & habitat for invertebrates.
52
mesopores
30 – 75 um, water is available to plants, filled with water at field capacity
53
micropores
5 -30 um, mainly unavailable to plants, held by adhesion to clay particles too strongly for plants to use
54
what pore size allows water to drain freely at saturation?
macropores
55
what are the benefits of macropores?
Increases aeration, root penetration & habitat for invertebrates
56
what size pores is water unavailable to plants due to adhesion?
micropores
57
what size pores is water unavailable to plants b/c they're filled with water at the field capacity?
mesopores
58
Without aggregation, pore size would be a function of _______ ______
soil texture
59
what pore size do fine-textured soils (clay) have?
predominantly micropores
60
what pore size do coarse-textured soils (sand) have?
predominantly macropores
61
why is it important for soils to have a variation in pore size?
allow the plant to have available soil moisture & adequate aeration
62
how can fine-textured soils have the same benefits as coarse-textured soils? what are these benefits? (3)
good aggregate structure benefits: good water infiltration, aeration & root penetration

Plant (21 decks)

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