Agroecosystems Flashcards
(85 cards)
1
Q
name the 11 abiotic factors which affect agriculture
A
- temp
- H2O
- light
- soil fertility/nutrients
- topography
- relief
- pH
- CO2
- soil salinity
- aeration
- wind velocity
2
Q
the importance of the correct temp in agriculture (4)
A
- warm enough to grow
- frost free periods
- increase temp = increase biochemical reactions
- thermoregulation (animals warm = reduce heat losses)
3
Q
how to control temp ?
A
- greenhouses (heat by paraffin)
- burning gas/oil in orchards
- south facing slopes in northern hemisphere (more insolation)
4
Q
give 2 plant species that are affected by temp
A
- grass don’t grow below 5°C
- maize damaged by frost
5
Q
importance of light in agriculture (2)
A
- higher intensity = more photo.
2. photoperiodism (daylength) affects growth + reproduction of livestock
6
Q
how to control light?
A
artificial light
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
8
Q
importance of H2O in agriculture (3)
A
- physiological solvent
- cell turgidity
- replace H2O from transpiration
9
Q
name the 2 problems caused by waterlogged soils
A
- fungal diseases
2. anaerobic = denitrification = reduce fertility
10
Q
give 2 problems caused by H2O shortage
A
- cell dehydration = stop biochemical reactions
2. trampling damage/erosion/desertification from livestock walking to get H2O
11
Q
how do you reduce H2O in agriculture? (2)
A
- drainage pipes/ditches
2. deep ploughing
12
Q
how do you increase H2O in agriculture? (3)
A
- crop irrigation
- soil mulching (reduce evap)
- addition of OM (increase retention)
13
Q
give the name of a species that needs lots of H2O and one that doesn’t
A
lots: rice
little: wheat
14
Q
importance of soil fertility/nutrients in agriculture?
A
plants need macro + micronutrients i.e. micronutrient iron for chlorophyll
15
Q
how to increase soil fertility/nutrients? (4)
A
- legumes
- crop rotation
- fertilisers
- free living soil bacteria (Azotobacter)
16
Q
low fertility of the soil may be able to support…
A
grazing livestock i.e goats
17
Q
name the 4 advantages of hydroponics
A
- nutrient supply optimal
- roots in contact with solution (growth directed to crop)
- no soil = no pathogens
- harvested crops have roots = stay more fresh
18
Q
name the 2 disadvantages of hydroponics
A
- increase input of energy/nutrients
2. increase level of technical knowledge
19
Q
how is productivity maximised in hydroponics
A
controlling limiting factors
20
Q
importance of topography in agriculture? (4)
A
- aspect: valleys produce areas with more insolation
- low lying land = frost pocket
- runoff rate
- use of machinery difficult to operate on steep slope
21
Q
how to manage topography? (2)
A
- terracing = steep to flat fields
2. nearly flat land leveled out = reduce irrigation
22
Q
importance of relief in agriculture (2)
A
altitude controls crops (adapted to low temps) and livestock (adapted to altitudes/low temps)
23
Q
can relief be controlled?
A
no it’s not possible
24
Q
importance of pH in agriculture? (2)
A
- low pH = leaching of nutrients
2. increase pH = inhibit nutrient solubility
25
how to increase and decrease pH?
increase: crushed lime
decrease: powdered sulfur
26
name 1 crop that can survive in alkaline soils and 1 in acidic
alk: garlic
aci: carrots
27
importance of CO2 in agriculture
can be a limiting factor of photo
28
how to increase CO2?
in greenhouses burn paraffin or gas
29
importance of soil salinity in agriculture? (2)
1. salt essential for growth
| 2. too high = osmotic dehydration
30
how to reduce salt content in soil? (2)
1. don't irrigate with H2O with high salt content
| 2. extra H2O can wash salt out soil
31
name 2 plant species that are sensitive to salt
peas/beans
32
importance of aeration of soil in agriculture? (2)
1. increase aerobic processes = increase fertility
| 2. O2 for soil biota, respiration
33
how to increase aeration (4)
1. increase OM (food for biota)
2. low tillage = reduce disturbance/killing of biota
3. limit use of heavy machinery
4. ploughing
34
problems of high wind velocity in agriculture? (3)
1. increase evap rates + drying of soil
2. increase soil erosion
3. crop damage
35
how to reduce wind velocity?
windbreaks i.e. rows of trees/hedgerows
36
name the 3 technological factors in agriculture
1. availability of energy
2. mechanisation
3. transport infrastructure
37
why is availability of energy important in agriculture? (3)
1. fuel needed in intensive farming (ploughing etc)
2. haber process (inorganic fertilisers)
3. energy to make pesticides
38
why is mechanisation important in agriculture?
1. intensive farming on a large scale i.e. processing
| 2. irrigation system (can be grown in dry conditions)
39
why is transport infrastructure important in agriculture? (2)
1. improvements to long distance transport: exportation of food
2. rapid transport (perishable foods i.e. grapes can be transported)
40
name the 3 social + ethical factors when choosing products
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
name 3 ways pests cause damage
1. death of livestock/crop
2. decrease quality of harvest
3. reduce harvest due to competition
42
name the 3 categories of pests
predators, competitors, pathogens
43
name the 4 pest groups
insects, fungi, weeds, bacteria
44
give 2 reasons why insects are pests + give an example for each
1. eat/destroy/reduce harvest i.e. locust
| 2. act as vectors, spread pathogens i.e. aphids carry potato blight
45
give a reason why fungi is a pest and an example
cause crop to rot i.e. leaf blight of sugarcane
46
give 3 reasons why weeds are pests and 1 example
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
give a reason why bacteria is a pest + 1 example
cause disease = reduction in harvest i.e. bacterial leaf blight of wheat
48
what are the 5 properties of a pesticide?
1. toxicity
2. specificity
3. mode of action
4. persistence
5. solubility
49
what is toxicity in pesticides? (2)
- most work by inhibiting enzymes
| - higher toxicity = lower vol. needed
50
why is specificity important for pesticides?
more specific = less range of non target species killed
51
what is specificity in pesticides?
a measure of the range of taxa affected by a pesticide
52
what is the issue of pesticides being persistent? (2)
1. degrades slowly = stays in environment longer
| 2. biomagnification
53
what is the issue if pesticides are soluble in H2O?
washed off during rainfall = pollute waterways
54
what is the issue of pesticides being liposoluble?
bioaccumulation which leads to biomagnification
55
what is bioaccumulation?
when liposoluble pesticides cross cell membranes, can't be excreted = builds up
56
what is a systemic pesticide?
absorbed by crop + transported thru out plant
57
what is a contact pesticide? and what are the 2 issues with it?
kill insects which come into contact with sprayed crop
- spray might wash off
- unsprayed parts unprotected
58
name the 4 pesticides
1. organochlorines
2. organophosphates
3. pyrethroids
4. neonicotinoids
59
give the 3 advantages of organochlorines
1. high toxicity to insects
2. low toxicity to vertebrates + mammals
3. low solubility in H2O
4. high persistence
60
why can high persistence be good in pesticides?
doesn't have to be reapplied regularly
61
give the 3 disadvantages of organochlorines
1. liposoluble (biomagnify) i.e. kill herons/ otters
2. high toxicity (death of non target species i.e. bees/ butterflies)
3. high persistence
62
give 2 advantages of organophosphates
1. low persistence
| 2. low liposolubility
63
give 3 disadvantages of organophosphates
1. high mammalian toxicity
2. suspected to be carcinogenic
3. associated with depression/ADHD
64
give 3 advantages of pyrethroids
1. low mammalian toxicity
2. high insect toxicity
3. not persistent (doesn't biomagnify)
65
give 2 disadvantage of pyrethroids
1. toxic to fish
| 2. can kill non-target insects
66
give 2 advantages of neonicotinoids
1. relatively persistent + H2O soluble = can be absorbed by plant
2. low toxicity to invertebrates
67
give 3 disadvantages of neonicotinoids
1. very toxic to bees
2. H2O soluble = build up in aquifers
3. broken down in presence of sunlight/soil microbes
68
name the 8 types of cultural pest control
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
describe crop rotation method
cultivation of different crop each year = pests will die as harder to colonise
70
describe companion crop method + an example
- crops grown together to increase productivity
- either both harvestable or 1 increase yield of other
i. e. intercropping with legumes
71
describe barrier crop method + example
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
describe predator habitat method + example
providing a suitable habitat for natural pest predators
| i.e. beetle bans/nest boxes
73
describe biological control
- using predators/pathogens to control pests
| - biological control + pest should be in balance (no adverse effect)
74
give 2 examples of biological control
1. ladybirds killing aphids
| 2. introducing Cactoblastis moth to Australia to control invasive prickly pear cactus
75
give the 3 disadvantages of biological control
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
give a biological control example which went wrong
Cane toad introduced to Australia to control pests of sugarcane but became a pest as it predated on many non-target species
77
describe the sterile male technique + example
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
describe pheromone trap method + 2 ways in which it is used
releases artificial pheromones to attract male/female
1. kill enough of 1 gender so no offspring
2. show if pests are present
79
describe genetic resistance method + example
through selective breeding or genetic modification
| i.e. Boran cattle more resistant to East coast fever
80
name the 3 reasons why antibiotics are used in agriculture
1. promote growth
2. prevent infection
3. treat infection
81
how are antibiotics used to promote growth?
reduce non-pathogenic gut bacteria so increases amount of food converted into growth = increases productivity
82
name the 2 problems of using antibiotics
1. if used as growth promoters = higher risk of becoming antibiotic resistant
2. could transfer resistant bacteria to humans i.e. E.Coli
83
what are zoonoses?
diseased transferred to humans
84
give 3 ways to increase pollinator pop.
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
why is it important to maintain soil biota?
1. breakdown DOM = release nutrients
| 2. worms aerate soil (aerobic processes + drainage)
