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Environmental science > Agroecosystems > Flashcards

Agroecosystems Flashcards

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1
Q

name the 11 abiotic factors which affect agriculture

A
  1. temp
  2. H2O
  3. light
  4. soil fertility/nutrients
  5. topography
  6. relief
  7. pH
  8. CO2
  9. soil salinity
  10. aeration
  11. wind velocity
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2
Q

the importance of the correct temp in agriculture (4)

A
  1. warm enough to grow
  2. frost free periods
  3. increase temp = increase biochemical reactions
  4. thermoregulation (animals warm = reduce heat losses)
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3
Q

how to control temp ?

A
  1. greenhouses (heat by paraffin)
  2. burning gas/oil in orchards
  3. south facing slopes in northern hemisphere (more insolation)
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4
Q

give 2 plant species that are affected by temp

A
  • grass don’t grow below 5°C

- maize damaged by frost

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5
Q

importance of light in agriculture (2)

A
  1. higher intensity = more photo.

2. photoperiodism (daylength) affects growth + reproduction of livestock

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6
Q

how to control light?

A

artificial light

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7
Q

give 2 species which are affected by light

A
  • oat = needs long periods of light

- artificial light can induce a second lambing season

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8
Q

importance of H2O in agriculture (3)

A
  1. physiological solvent
  2. cell turgidity
  3. replace H2O from transpiration
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9
Q

name the 2 problems caused by waterlogged soils

A
  1. fungal diseases

2. anaerobic = denitrification = reduce fertility

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10
Q

give 2 problems caused by H2O shortage

A
  1. cell dehydration = stop biochemical reactions

2. trampling damage/erosion/desertification from livestock walking to get H2O

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11
Q

how do you reduce H2O in agriculture? (2)

A
  1. drainage pipes/ditches

2. deep ploughing

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12
Q

how do you increase H2O in agriculture? (3)

A
  1. crop irrigation
  2. soil mulching (reduce evap)
  3. addition of OM (increase retention)
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13
Q

give the name of a species that needs lots of H2O and one that doesn’t

A

lots: rice
little: wheat

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14
Q

importance of soil fertility/nutrients in agriculture?

A

plants need macro + micronutrients i.e. micronutrient iron for chlorophyll

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15
Q

how to increase soil fertility/nutrients? (4)

A
  1. legumes
  2. crop rotation
  3. fertilisers
  4. free living soil bacteria (Azotobacter)
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16
Q

low fertility of the soil may be able to support…

A

grazing livestock i.e goats

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17
Q

name the 4 advantages of hydroponics

A
  1. nutrient supply optimal
  2. roots in contact with solution (growth directed to crop)
  3. no soil = no pathogens
  4. harvested crops have roots = stay more fresh
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18
Q

name the 2 disadvantages of hydroponics

A
  1. increase input of energy/nutrients

2. increase level of technical knowledge

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19
Q

how is productivity maximised in hydroponics

A

controlling limiting factors

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20
Q

importance of topography in agriculture? (4)

A
  1. aspect: valleys produce areas with more insolation
  2. low lying land = frost pocket
  3. runoff rate
  4. use of machinery difficult to operate on steep slope
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21
Q

how to manage topography? (2)

A
  1. terracing = steep to flat fields

2. nearly flat land leveled out = reduce irrigation

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22
Q

importance of relief in agriculture (2)

A

altitude controls crops (adapted to low temps) and livestock (adapted to altitudes/low temps)

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23
Q

can relief be controlled?

A

no it’s not possible

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24
Q

importance of pH in agriculture? (2)

A
  1. low pH = leaching of nutrients

2. increase pH = inhibit nutrient solubility

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25
Q

how to increase and decrease pH?

A

increase: crushed lime
decrease: powdered sulfur

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26
Q

name 1 crop that can survive in alkaline soils and 1 in acidic

A

alk: garlic
aci: carrots

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27
Q

importance of CO2 in agriculture

A

can be a limiting factor of photo

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28
Q

how to increase CO2?

A

in greenhouses burn paraffin or gas

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29
Q

importance of soil salinity in agriculture? (2)

A
  1. salt essential for growth

2. too high = osmotic dehydration

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30
Q

how to reduce salt content in soil? (2)

A
  1. don’t irrigate with H2O with high salt content

2. extra H2O can wash salt out soil

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31
Q

name 2 plant species that are sensitive to salt

A

peas/beans

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32
Q

importance of aeration of soil in agriculture? (2)

A
  1. increase aerobic processes = increase fertility

2. O2 for soil biota, respiration

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33
Q

how to increase aeration (4)

A
  1. increase OM (food for biota)
  2. low tillage = reduce disturbance/killing of biota
  3. limit use of heavy machinery
  4. ploughing
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34
Q

problems of high wind velocity in agriculture? (3)

A
  1. increase evap rates + drying of soil
  2. increase soil erosion
  3. crop damage
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35
Q

how to reduce wind velocity?

A

windbreaks i.e. rows of trees/hedgerows

36
Q

name the 3 technological factors in agriculture

A
  1. availability of energy
  2. mechanisation
  3. transport infrastructure
37
Q

why is availability of energy important in agriculture? (3)

A
  1. fuel needed in intensive farming (ploughing etc)
  2. haber process (inorganic fertilisers)
  3. energy to make pesticides
38
Q

why is mechanisation important in agriculture?

A
  1. intensive farming on a large scale i.e. processing

2. irrigation system (can be grown in dry conditions)

39
Q

why is transport infrastructure important in agriculture? (2)

A
  1. improvements to long distance transport: exportation of food
  2. rapid transport (perishable foods i.e. grapes can be transported)
40
Q

name the 3 social + ethical factors when choosing products

A
  1. culturally some animals not eaten i.e. snails
  2. religions have dietary restrictions
  3. choices on welfare of animals i.e. free range eggs
41
Q

name 3 ways pests cause damage

A
  1. death of livestock/crop
  2. decrease quality of harvest
  3. reduce harvest due to competition
42
Q

name the 3 categories of pests

A

predators, competitors, pathogens

43
Q

name the 4 pest groups

A

insects, fungi, weeds, bacteria

44
Q

give 2 reasons why insects are pests + give an example for each

A
  1. eat/destroy/reduce harvest i.e. locust

2. act as vectors, spread pathogens i.e. aphids carry potato blight

45
Q

give a reason why fungi is a pest and an example

A

cause crop to rot i.e. leaf blight of sugarcane

46
Q

give 3 reasons why weeds are pests and 1 example

A
  1. provide food for other pests
  2. compete with crop
  3. harvested with crop = reduce quality
    i. e. wild oats compete with cereal crops
47
Q

give a reason why bacteria is a pest + 1 example

A

cause disease = reduction in harvest i.e. bacterial leaf blight of wheat

48
Q

what are the 5 properties of a pesticide?

A
  1. toxicity
  2. specificity
  3. mode of action
  4. persistence
  5. solubility
49
Q

what is toxicity in pesticides? (2)

A
  • most work by inhibiting enzymes

- higher toxicity = lower vol. needed

50
Q

why is specificity important for pesticides?

A

more specific = less range of non target species killed

51
Q

what is specificity in pesticides?

A

a measure of the range of taxa affected by a pesticide

52
Q

what is the issue of pesticides being persistent? (2)

A
  1. degrades slowly = stays in environment longer

2. biomagnification

53
Q

what is the issue if pesticides are soluble in H2O?

A

washed off during rainfall = pollute waterways

54
Q

what is the issue of pesticides being liposoluble?

A

bioaccumulation which leads to biomagnification

55
Q

what is bioaccumulation?

A

when liposoluble pesticides cross cell membranes, can’t be excreted = builds up

56
Q

what is a systemic pesticide?

A

absorbed by crop + transported thru out plant

57
Q

what is a contact pesticide? and what are the 2 issues with it?

A

kill insects which come into contact with sprayed crop

  • spray might wash off
  • unsprayed parts unprotected
58
Q

name the 4 pesticides

A
  1. organochlorines
  2. organophosphates
  3. pyrethroids
  4. neonicotinoids
59
Q

give the 3 advantages of organochlorines

A
  1. high toxicity to insects
  2. low toxicity to vertebrates + mammals
  3. low solubility in H2O
  4. high persistence
60
Q

why can high persistence be good in pesticides?

A

doesn’t have to be reapplied regularly

61
Q

give the 3 disadvantages of organochlorines

A
  1. liposoluble (biomagnify) i.e. kill herons/ otters
  2. high toxicity (death of non target species i.e. bees/ butterflies)
  3. high persistence
62
Q

give 2 advantages of organophosphates

A
  1. low persistence

2. low liposolubility

63
Q

give 3 disadvantages of organophosphates

A
  1. high mammalian toxicity
  2. suspected to be carcinogenic
  3. associated with depression/ADHD
64
Q

give 3 advantages of pyrethroids

A
  1. low mammalian toxicity
  2. high insect toxicity
  3. not persistent (doesn’t biomagnify)
65
Q

give 2 disadvantage of pyrethroids

A
  1. toxic to fish

2. can kill non-target insects

66
Q

give 2 advantages of neonicotinoids

A
  1. relatively persistent + H2O soluble = can be absorbed by plant
  2. low toxicity to invertebrates
67
Q

give 3 disadvantages of neonicotinoids

A
  1. very toxic to bees
  2. H2O soluble = build up in aquifers
  3. broken down in presence of sunlight/soil microbes
68
Q

name the 8 types of cultural pest control

A
  1. crop rotation
  2. barrier crops
  3. predator habitats
  4. pheromone traps
  5. biological control
  6. sterile male techniques
  7. companion crops
  8. genetic resistance.
69
Q

describe crop rotation method

A

cultivation of different crop each year = pests will die as harder to colonise

70
Q

describe companion crop method + an example

A
  • crops grown together to increase productivity
  • either both harvestable or 1 increase yield of other
    i. e. intercropping with legumes
71
Q

describe barrier crop method + example

A

a plant which prevents the other plant being destroyed/eaten by pests i.e. smell of onions mask smell of carrots for carrot root fly

72
Q

describe predator habitat method + example

A

providing a suitable habitat for natural pest predators

i.e. beetle bans/nest boxes

73
Q

describe biological control

A
  • using predators/pathogens to control pests

- biological control + pest should be in balance (no adverse effect)

74
Q

give 2 examples of biological control

A
  1. ladybirds killing aphids

2. introducing Cactoblastis moth to Australia to control invasive prickly pear cactus

75
Q

give the 3 disadvantages of biological control

A
  1. control not immediate
  2. control may become pest
  3. pests not eradicated (as no. of control decreases as their food, the pests, decrease)
76
Q

give a biological control example which went wrong

A

Cane toad introduced to Australia to control pests of sugarcane but became a pest as it predated on many non-target species

77
Q

describe the sterile male technique + example

A
  1. if female mate with sterile male = no offspring
  2. no. of fertile mating reduced = pop. declines
  3. expose males to gamma radiation
    i. e. mosquitoes
78
Q

describe pheromone trap method + 2 ways in which it is used

A

releases artificial pheromones to attract male/female

  1. kill enough of 1 gender so no offspring
  2. show if pests are present
79
Q

describe genetic resistance method + example

A

through selective breeding or genetic modification

i.e. Boran cattle more resistant to East coast fever

80
Q

name the 3 reasons why antibiotics are used in agriculture

A
  1. promote growth
  2. prevent infection
  3. treat infection
81
Q

how are antibiotics used to promote growth?

A

reduce non-pathogenic gut bacteria so increases amount of food converted into growth = increases productivity

82
Q

name the 2 problems of using antibiotics

A
  1. if used as growth promoters = higher risk of becoming antibiotic resistant
  2. could transfer resistant bacteria to humans i.e. E.Coli
83
Q

what are zoonoses?

A

diseased transferred to humans

84
Q

give 3 ways to increase pollinator pop.

A
  1. introduction of bee hives
  2. restrict use of pesticides that harm pollinators
  3. provision of food supplies i.e. plants that provide nectar
85
Q

why is it important to maintain soil biota?

A
  1. breakdown DOM = release nutrients

2. worms aerate soil (aerobic processes + drainage)

Environmental science (19 decks)

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