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Plant > Lecture 7 > Flashcards

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
Q

what soil texture has the lowest drainage?

A

clay

26
Q

what soil texture has the highest drainage?

A

sand

27
Q

what soil texture has the lowest water holding capacity?

A

sand

28
Q

what soil texture has the highest water holding capacity?

A

clay

29
Q

what soil texture has the lowest aeration?

A

clay

30
Q

what soil texture has the highest aeration?

A

sand

31
Q

loams (L)

A

medium textured soils made up of a mixture of sand, silt & clay and are considered to be “ideal”

32
Q

cation exchange capacity (CEC)

A

index of soil fertility

33
Q

are many essential plant nutrients anions or cations?

A

cations

34
Q

incres SA = ______ CEC

A

higher

35
Q

why is a high CEC desirable?

A

can attract & hold nutrients & make them available to plants

36
Q

soil structure

A

the form & degree of aggregation of soil mineral particles

37
Q

Soil primary particles are arranged into secondary particles known as ______ or _____

A

peds or aggregations

38
Q

how do peds or aggregations vary?

A

Size & shape

39
Q

what compounds act as cementing agents that form aggregates?

A

Clay, organic matter & other compounds

40
Q

what factors does soil structure effect? (4)

A

pore size

water holding capacity

infiltration rates

permeability of water and air

41
Q

what does poor soil structure (low aggregation) effect?

A

root penetration

reduces plant vigor

42
Q

soil moisture availability is dependent on what 2 factors?

A

soil texture & structure

43
Q

how does the water availability change when moving from sand to clay? why?

A

more water attached to the particles

clay particles are smaller

44
Q

what draws water down through the soil?

A

gravity

45
Q

what force attracts water molecules to each other?

A

cohesion

46
Q

what force attracts water to the surface of the soil particles?

A

adhesion

47
Q

water experiencing cohesion is ______ available to plants

A

highly

48
Q

water experiencing adhesion is ______ available to plants

A

largely not

49
Q

what are the materials forming soil aggregates? (6)

A

fungal hyphae

roots

microbes

humus

clay

inorganic materials (minerals)

50
Q

humus

A

organic material but is very degraded that is no longer seen as organic mater, dark coloured

51
Q

macropores

A

> 75 um water will drain freely at saturation. Increases aeration, root penetration & habitat for invertebrates.

52
Q

mesopores

A

30 – 75 um, water is available to plants, filled with water at field capacity

53
Q

micropores

A

5 -30 um, mainly unavailable to
plants, held by adhesion to clay particles too
strongly for plants to use

54
Q

what pore size allows water to drain freely at saturation?

A

macropores

55
Q

what are the benefits of macropores?

A

Increases aeration, root penetration & habitat for invertebrates

56
Q

what size pores is water unavailable to plants due to adhesion?

A

micropores

57
Q

what size pores is water unavailable to plants b/c they’re filled with water at the field capacity?

A

mesopores

58
Q

Without aggregation, pore size would be a function of _______ ______

A

soil texture

59
Q

what pore size do fine-textured soils (clay) have?

A

predominantly micropores

60
Q

what pore size do coarse-textured soils (sand) have?

A

predominantly macropores

61
Q

why is it important for soils to have a variation in pore size?

A

allow the plant to have available soil moisture & adequate aeration

62
Q

how can fine-textured soils have the same benefits as coarse-textured soils? what are these benefits? (3)

A

good aggregate structure

benefits: good water infiltration, aeration & root penetration

Plant (21 decks)

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