agriculture Flashcards
main issues
-impact on biosphere
-use of environmental resources
-pollution
-development and globalisation
-food for human survival
agroecosystem
-farmland is an artificial ecosystem or agroecosystem
-community of species interacting with each other and their physical environment
-controlled by humans
importance of light in agriculture
-better light=more rapid photosynthesis
-day length
-some plants require longer period of light each day for flowering
-other plants require shorter days
-day length affects reproductive function of some livestock species
CONTROL OF LIGHT
-artificial lighting- extended growing season
importance of water in agriculture
-physiological functions- cell turgity
-nutrient absorption- dissolved as ions in water
-used to transport materials- oxygen, glucose, minerals
-transpiration- water leaves via stomata, allows exchange
how does water supply affect crops
-high water requirements- e.g. most rice varieties must be flooded during early growth
-low water requirements- e.g. cereal crops; wheat
-irregular supply- e.g. tomatoes crops can expand and split
-humid conditions- inc risk of fungal diseases
-farmers must consider- amount, reliability, quality
how can we control problems with water supply? (waterlogged soils)
problems-
-fungal disease
-anaerobic dentrifying bacteria
-reduced fertility
solutions-
-excavate drainage areas
-install drainage pipes
-deep ploughing
-avoid soil compaction
how can we control problems with water supply? (drought)
problems-
-inhibits crop growth- transpiration in crops, prevents gas exchange
-eventually death- dehydration inhibits crop biochemistry
-death of livestock
-trampling, compaction, erosion by moving livestock
-desertification
solutions-
-irrigation
-soil mulching
-inc filtration
-reduce soil compaction
-inc organic matter content
what types of technologies benefit agriculture
-machinery and equipment
-pesticides
-fertilisers
-genetic improvements through breeding programs
-support infrastructure
gps mapping, drones and satellite surveys
-rate of photosynthesis
-biomass estimation
-soil water content
-spread of pests and diseases
-cropped areas of fields
how has transport development improved agroecosystem suitability?
-long distance, rapid, bulk transport has become easier
-transportation of perishable foods has become possible
-foods can now be produced in areas where there is no local demand and then transport them to consumers
-relative costs of transporting goods have generally gone down as fuel costs have declined
how has mechanisation improved agroecosystem suitability?
-machinery allows large scale ploughing, spearing of agrochemicals and harvesting
-industries such as food processing, storage and equipment maintenance can support food production
why are nutrients important in agriculture?
-macronutrients-needed in large quantities
-micronutrients-needed in small quantities
-nutrients added to soil after crops are harvested
-nutrients can be added by fertiliser as or natural processes
-nitrogen fixing bacteria:
•rhizobium- symbiotic in root nodules
•azotobacter- lives free in soil weathering
how are fertilisers applied?
organic fertilisers
-faecal manure/sewage
-animal food production wastes
-plant food production wastes
advantages:
-locally sourced
-inc humus layer content
-inc soil biota
disadvantages:
-nutrients compensation can’t be controlled
-expensive to transport
-usually can’t be added to already growing crops
how are fertilisers applied?
inorganic fertilisers
-synthetic fertilisers
advantages:
-control nutrient composition
-nutrients released rapidly
disadvantages:
-leaching
-toxic to detritivores
-doesn’t add organic matter to soils, so humus & biota levels decline
how does topography affect crops?
importance:
-machinery-may be difficult to operate large machinery on land that undulates a lot
-runoff rate-steeper gradients make soil erosion by surface runoff more likely
-frost pockets-cold denser air may collect in low lying areas, crop frost damage
control:
-flat fields by terracing- retain irrigation water & reduce soil erosion
-areas nearly flat levelled by machinery so water drains slowly
how does relief affect crops?
-altitude of an area controls other factors that affect the choice of species for cultivation
-crops-temps are often colder at high altitudes. the low atmospheric pressure increases evaporation rate
-livestock- some species adapted to high altitudes. they can survive lower temps &low atmospheric pressures
control:
-not possible
how does soil aeration affect affect agroecosystem suitability?
-many important soil processes are aerobic such as root respiration, nitrogen fixation, decomposition
-force of gravity compacts soil particles
-counteracted by tunnelling action of detritivores & growth of plant roots
control:
-add organic matter provides food for soil biota
-low tillage methods prevent disturbance of soil
-removing livestock from fields when soil is very wet
how does soil pH affect agroecosystem suitability?
-high pH can inhibit nutrient solubility
-low pH can inc leaching of nutrients & inhibit nutrient uptake
-can be increased by added crushed lime
-can be reduced by spreading powdered sulphir
how does wind velocity affect agroecosystem suitability
-high wind velocities cause several problems:
•inc soil erosion, especially in dry areas
•inc evaporation rates & the drying of soils
•crop damage e.g. ‘lodging’ of cereal crops when they are flattened by strong winds
control:
-windbreaks such as hedgerows or rows of trees
how does soil salinity affect agroecosystem suitability?
-dissolved salts in soil water are essential for plant growth as they include soil nutrients but excessive salinity can kill plants by osmotic dehydration of their roots
control:
-avoid farming methods that inc salinity, especially irrigating with groundwater that has a high salt content.
what biotic factors affect productivity?
agroecosystems
-often a monoculture, very low biodiversity
-indigenous species, both plants & animals are cleared
-however the new ecosystem will be taken advantage of by a new community of species
-pests- any organism that reduces the quality or productivity of crops or livestock in any way
-beneficial organisms-pollinators or soil organisms to recycle nutrients
how can pests damage crops?
-pathogens: reduce harvest due to ill health of the crops or livestock. cause human disease
-competition: reduced harvest due to competition for water, light, nutrients etc
-quality and quantity: reduced quality of harvest (taste, appearance, storability). reduced quantity of harvest
what are the different types of pest?
-endemic pests- always present, usually in small or moderate numbers
-epidemic pests- not normally present but there may be ‘outbreaks’ where they rapidly become a major problem
-indigenous species- native to the area where they are found
-introduced species- found in an area where they aren’t naturally found. these are often more of a problem as they may not have any predators in new areas
different types of pests
-weeds- compensation for resources, provides food for other pests, some species are parasites, draining resources directly from crops, e.g. wild oats in cereal crops and striga parasites maize
-insects- eat and destroy crops reducing harvest, vectors for pathogens, e.g. aphids
-fungi- cause the growing plants or harvested crop to rot, e.g. leaf smut
-bacteria- reduce harvests by causing disease, e.g. bacterial wilt
-molluscs- eat the crop, reduce harvests, or spoil appearance e.g. snails
-vertebrates- eat growing or harvested crop, e.g. mice
why is pest control needed?
-approx 1/3 of wolds food is lost due to pests & associated disease- most serious in low income countries
-pest sometimes is most important for large scale & intensive farming
-monocultures can easily lead to infestation
-intensive farming large numbers of animals kept close together, making disease & pests easier to spread
cultural control methods, advantages and disadvantages
-crop rotation: +prevents build up of pests & diseases specific to certain areas. -requires long term planning
-barrier crops: +help protect soil from wind erosion, reduce top soil loss. -cost, time required to plant during the busy harvest season
-companion crops: +pest control, improved soil health. -competition for resources, inc maintenance
-predator habitats
what are pesticides
-toxic chemicals used to kill pests
-very effective rapid control
-can be longer term problems caused by their use
crop pesticide application:
-spraying of crops in fields
-powder coating of seeds
-soil injection to kill pests in soil
livestock pesticide application:
-dipping of livestock to kill skin parasites
-drenching where livestock drink pesticides to kill internal pesticides
how does toxicity affect pesticide use
-intended to be poisonous to kill pests (target organism)
-may also be poisonous to other organisms
-difference in toxicities to pests & to non target species is important in assessing likelihood of pesticide causing environmental damage
-high toxicity pesticides= smaller volumes
-most pesticides act by inhibiting enzyme action
why is pesticide specificity important
-some pesticides are ‘broad spectrum’ and kill wide range of species
-others are ‘narrow spectrum’ and kill smaller range as they’re more specific
-broad spectrum more likely to kill non target organisms
how does persistence affect pesticide use
-persistent pesticides break down slowly
-more likely to remain in environment for longer periods
-reduces frequency of re-application
-travel long distances
-travel along food chains
how does solubility affect pesticide use
-liposoluble pesticides build up in organisms and food chains
-concentration may build up until it’s toxic to non target organisms
-pesticides that are water soluble are more likely to be washed off crop, requiring re-application
what are contact pesticides
contact action:
-only protects surface of crop that are sprayed
-un sprayed surfaces aren’t protected
systematic action:
-absorbed by crop & translocated through crop
-protects all of plant
-can’t be washed off by rain & be eaten by humans
how can antibiotics be used in agriculture
-treat bacteria infections
-prevent infection
-promote growth
problems with using antibiotics in agriculture
-antibiotic resistance
-risk of zoonosis- inc some resistant bacteria are transferred to humans
how can pollinator services be aided
-provision of food supplies by growing plants that provide nectar
-restricting use of harmful pesticides
-introduction of bee hives
-companion crops
-habitat protection
how are nutrients supplied to soil?
-includes maintenance of soil biota, detritivores & decomposers
-nutrient supply in an abiotic factor controlled in agroecosystems
-nutrient supplies is a natural processes e.g. nitrogen fixing bacteria, decomposition & crop rotation
-nutrient supplies control productivity in different areas
what is soil biota
-all microorganisms, soil animals and plants living all/part of their lives in or on soil
-nitrogen fixing bacteria- convert nitrogen into nitrates
why is soil biota important
-inc nutrient supply via breakdown of DOM & nitrogen fixation
-organic acids produced by decomposition inc weathering of rocks & releases nutrients into soil
-earthworms inc aeration & drainage which aid aerobic process & water retention
integrated pest control
-effective and environmentally sensitive approach to pest management that relies on a combination of common sense practices
advantages & disadvantages of cultural pest control
+prevente build up of pests
+cheap
+improve soil health
+environmentally sensitive
-long term planning
-maintenance
-slow acting
-won’t remove all pests
advantages & disadvantages of pesticides
+kills pest
+high volume
-cost
-machinery to apply
-persistent
-can kill non target species
advantages and disadvantages of integrated pest control
+environmentally sensitive
+control pests
-long term planning
what is biomass
-total mass of living material in a specific areas at a given time
-net primary production-rate at which autotrophs synthesise organic compounds from atmospheric or aqueous carbon dioxide minus the rate at which these compounds are used
autotrophs and heterotrophs
-autotrophs- things that make their own food
-heterotrophs- have to eat food, can make their own
how is energy transferred between tropic levels?
-producers are mostly plants & algae which transfer 1% of the incident energy from light for photosynthesis
-approx 10% of biomass from each tropic level is transferred to lvl above it
how is energy lost between trophies levels
losses of biomass are due to:
-not all ingested material is absorbed, some is egested as faeces
-some absorbed materials is lost as waste, such as carbon dioxide and water in respiration & water and urea in urine
-large amounts of glucose used in respiration
-some parts of an organism are inedible
problems with food chains
-most energy in biomass at each tropic level can’t be passed on
-food chains should be as short as possible for the best energy efficiency
•limit movement
•maintain temperature
•reduces energy loss by respiration
difference between intensive and extensive agriculture?
-extensive agriculture- maximises totally yield by spreading input over large areas of me
-intensive- large artificial inputs are available but over a small area of land
law of diminishing returns
-each extra input results in a increase in yield but by smaller amounts each time.
-global scale- food production yield would increases if inputs were evenly distributed.
energy subsidies
-energy subsidy is an agricultural input to increase productivity but that requires energy.
-examples: manufacture of pesticides, processing of food for consumers, pumping of irrigation water
energy ratios
energy ratio is a measure of efficient when compared to energy inputs and outputs.
-expressed as the number of units of food energy produced per unit of energy input.
-the higher the yield per energy input have the highest energy ratio number.
-when considering livestock, food conversations ratios (FCRs) may be used instead
population manipulation
density
-higher density=increased yield.
-decreased induvial yield due to increased competition.
-increase risk of disease and pest outbreak.
monocultures
-cultivating a single species over a large area.
-easier to cultivate and use machinery.
-increase risk of disease and pest outbreak
asexual reproduction advantages
-rapid population growth
-energy efficient
-sturdier plants
-genetically identical to parent plant, predictable characteristics
-high survival rate
asexual reproduction disadvantages
-disease
-overpopulation
-competition
-harmful mutations to offspring
-vulnerable to pests
-no genetic variation in offspring so characteristics can’t be improved
natural vegetative propagation
-plants grow and develop without human intervention, using parts of the parent plant to grow new plants
artificial vegetative propagation
cuttings:
-cut end of stem put into damp soil, roots develop, plant hormones can be used to encourage root development, inc survival rate
micropropagation:
-small pieces of plant tissue grown on sterile nutrient medium containing sugars and mineral nutrients
asexual reproduction on animals-cloning
- cells are removed from donor & grown in culture
- eggs removed from female. nucleus of egg removed & replaced by nucleus from donor cells
- egg implanted into surrogate female where it develops during a normal pregnancy
- it has characteristics of donor when born
sexual reproduction- selective breeding
-production of offspring from parents chosen because of favourable genetic characteristics
-inc risk of inbreeding
-breeding between genetically similar individuals may produce offspring with similar characteristics
sexual reproduction- crossbreeding
-may produce a combination of desirable characteristics with ‘hybrid vigour’ and lower risk of inbreeding
-reduces problems caused by homozygous recessive genes often found in inbred varieties
-example- zebu cattle, reared in areas with a hot climate. they tolerate the heat well but give a low milk yield. ayrshire cattle from scotland give high milk yield but not heat tolerant
problems with inbreeding
-inc probability of undesirable recessive genes producing offspring with unwanted characteristics
social factors affecting agriculture
-personal choice about food have huge impact on market demand & farming methods
-strive for ‘perfect food’ is also putting inc demands in markets and leads to more food waste
cultural factors influencing agriculture
-range of traditions make particular food more or less popular
-e.g. in the uk we don’t usually eat horse meat or snails, although they’re commonly consumed in other countries
religious factors influencing agriculture
-people with religious convictions may avoid certain foods
-jews and muslims don’t eat prob while hindus don’t eat beef
ethical factors influencing agriculture
-a desire to reduce the environmental or social impacts of food production can influence food choices
-local food- buying food produced nearby reduces energy involved in transport
-seasonal food- choosing food grown where local weather is suitable has lower environmental impact than eating out of season food
-e.g. free range, organic foods, seasonality, food miles, veganism
economic & political factors influencing agriculture
-strategies often used to influence the food produced & methods used by agriculture
-can provide benefits but problems may also be created
grants and subsidies
-made available so European farmers could get financial assistance for wide range of incentives to inc food production like;
•drainage of wet fields
•grants to change production systems
•hedgerow removal to increase field size
•improved livestock
•liming to neutralise acidic soils
•purchase of machinery
These changes increased food production but had environmental impacts such as loss of hedgerows
market guarantee
-gov would set price for agricultural products
-farmers know theyd get paid when they harvested their crops or livestock.
-if there was surplus harvest then gov would buy some products of harvest from farmers creating artificial market shortage, causing prices to inc
-where possible harvest was stored e.g. grain, cheese
-f there was poor harvest the shortage in supply would cause the prices to rise.
-gov prevented this by selling just enough of previous years stored harvest to bring market price down to agreed amount.
This helped to create a stable market for farmers which in turn inc food production
food surpluses
Quotas
-farmers given limits on what theyre allowed to produce.
Farm diversification
-farmers told to focus on new products, non-food production activities e.g. public visit to working farms & specialised dairy production.
Alternative crops & livestock
-biofuels, pharmaceutical crops e.g. poppies, bees for honey.
Sat-aside
-farmers of surplus crops have been paid to take their farmland out of production but keeping it in condition where could be farmed if needed
agri-environment schemes
-range of schemes have given farmers a contribution to their income in ways that benefit the environment
•Environmental Sensitivities Areas (ESAs)
• Countryside Stewardship Schemes (CSS)
• Environmental stewardship schemes (ESS)
• Countryside stewardship (CS)
what is sustainability
-meeting needs of present without compromising ability of future generations to meet their own needs
-in agriculture: meeting food demands of current populations without destroying resources etc so future gens can meet own needs
how can we improve agriculture in sustainability
-use of agrochemicals
-pest control methods
-nutrient process & recycling
-energy subsidies
-hydrological cycle
-social considerations
what are pests
-organisms which reduce growth & productivity of crops & so reduce amount of food we can get from them
how do pests harm crops
-reduced harvest due to ill health if crop & livestock
-reduced harvest due to competition for water, light, nutrients
-killing crop
-risk of zoonosis
-reduced quantity of harvest-they eat ur
-taste appearance, storability
-human disease
liposoluble
-can dissolve in fats
monoculture
-growth of single type of crop, usually over large ares
organochlorine pesticide
-synthetic pesticide, kills mosquitoes, harmful to humans & animals eg DDT
systemic
-pesticide absorbed by plant, kills pests from within
why do we need pest control
-mainly important in monocultures and intensive rear
-1/3 of worlds harvest food is lost due to pests and diseases
advantages and disadvantages of pesticides
+kills pests
+high volume
+profit
-expensive
-machinery to apply
-persistent
-kills non target species
biological control
-use of another organism which kills pest
-less impact on environment
-could be parasite or predator
-aims to reduce numbers to below economic damage level
-eg greenfly and ladybird
advantages of biological control
-non toxic to humans
-sustainable
-targeted pest control
-pests less likely to develop resistance
-improve crop quality
-reduces chemical pesticide use
-cheaper in long run
disadvantages of biological pest control
-cost
-more time than pesticides
-non target species
-not every pest has predator or parasite to keep it under control
-will never kill all pests
-control organism may start to feed on other
crop rotation
-land can be more susceptible to erosion if same type of crop is repeatedly planted
-certain pests can reach levels that are hard to control when they learn to make home near field that always has same type of crop
-land itself can become ‘tired’ and less fertile, bc same type of crop planted repeatedly keeps draining land of same nutrients needed for that plants growth
variations in sunlight
-water depth greater than 100m has very limited light penetration
-reducing further depending on water turbidity
-photosynthesis limited to water surface layers (photic zone)
-organisms living at depth greater than 100m (aphotic zone) rely on food produced nearer surface carried down by currents or bodies of dead organisms
nutrient availability
-algae absorbs nutrients directly from water
-oceans have lots of co2 availability
-other nutrients like phosphates are less readily available & therefore a limiting factor
-photic zones have inc amount of phosphate due to run offs via riverbeds & via upwellings
pelagic trawling
-used for mid water shoals e.g. bass, anchovies, herring & mackerel
-adv- high catch rates, cost effective, less impact on seabed
-dis- bycatch, environmental impacts
demersal trawling
used for seabed species eg cod, haddock, plaice, shrimps & scampi
-adv- high catch rates, cost effective, catch wide range of species
-dis- habitat damage, bycatch, reduced biodiversity, coral damage
purse seining
-place net around shoal of fish. top floats, bottom weights then pull tight under shoal
-adv- efficient, low bycatch, sustainable
-dis- bycatch, stress on fish, pressure on fish stocks
drift netting
-curtain like nets supported by floats- catch pelagic species near surface eg herring, tuna
-adv- cost effective, target dispersed fish stocks efficiently, catch large quantities
-dis- bycatch, competition, illegal fishing
long lining
-lines of baited hooks, can be many km in length. tuna and squid target catch
-adv- reduced bycatch
-dis- ghost fishing
shellfish traps
-baited traps catch crustaceans on seabed
-adv- high species selectivity
environmental impacts of fishing
-overfishing
-bycatch
-ghost fishing
-habitat fishing: seabed damage, coral reef impact, seagrass beds, dynamite fishing, food web impacts
reducing environmental impacts of fishing
-catch quotes
-fishing equipment design & use
-restricted fishing methods
-minimum catchable size
-fishing effort limits
-closed seasons
-not take zones
-protected individuals
-captive breeding
catch quotas
-limits amount of fish you can catch. quota set based on time of year, type of fish & location of fishing. any fish over quota have to be thrown back, usually dead
fishing equipment design and use
-met can be modified to inc hole size or make material of the net stretchy. gives smaller juvenile fish a chance to escape & a chance to breed to inc population, allows larger stronger fish eg sharks to squeeze through net & not get caught
restricted fishing methods (no take zones & closed seasons)
-no take zones- an area where no fishing is allowed or made into a marine nature reserve , normally used in vulnerable areas like breeding grounds
-closed seasons- fishing is banned for a certain length of time. allows younger generation to be born & gives fish higher chance of surviving, also reduces impacts on environment
aquaculture
-control the aquatic ecosystem so more food enters human food chain
principles of aquaculture
-extensive= minimal input e.g. fish artificially added to pond so they can feed on wild food before being eaten
-intensive=greater inputs e.g. feeding with wastes, adding nutrients & control of competitors & predators
-extreme aquaculture= artificial control of both biotic & abiotic factors to maximise productivity
objectives of aquaculture
-boost economy
-generate employment
-utilise the natural water sources
-earn foreign exchange revenue
-culture ornamental fishes
-culture larvicidal fishes for control of mosquito larvae
-inc production of food in form of fish
open aquaculture systems
-farming of fish by enclosing them in caves or pens
-anchored in natural water ways, estuaries, bays, or other coastal marine environments
-juveniles are sourced from hatcheries of wild populations, protected from predators and fed regularly
open aquaculture systems
-simple structures placed in natural water body where fish or other aquatic organisms can naturally feed on available food sources, essentially ‘grazing’ on surrounding environment, without need for direct feeding by farmer
-environmentally friendly
semi closed aquaculture systems
-fish are contained within a physical barrier, typically an impermeable bag, that separates them from the open ocean environment, while still drawing clean water from deeper depths to provide cleaner, lice free water supply
closed aquaculture systems
-systems that raise aquatic organisms in a controlled environment, separate from natural environment
what is a tree
-perennial plant with the persistent wooden stem
hornbeam tree
-uk native
-deciduous, broadleaf tree
-pale grey bark with vertical markings, which develops ridges with age
-mature trees reach height of 30m & live for more than 300 years
-coppiced or pollarded
-keeps lower leaves all year round, provides shelter etc
-hard wood- used for flooring, furniture & wood turning
-threats- fungal disease like phytophthora, bark stripping damage by grey squirrels
tree uses
-timber
-food
-medicine
-fuel
-fibres
what is deforestation
-will occur if rate of clearance is faster than maximum rate of regrowth (natural or aided by humans)- maximum sustainable yield
causes
-agriculture- population increase
-mineral extraction- mining
-reservoirs- public supply of water, hydrological power
-urbanisation- expansion of urban areas. inc demand for food
-transport- construction for roads, railways & airports. barriers for wildlife & cause population fragmentation
deforestation in HICs and LICs
-agriculture- LICs
-mining- LICs
-reservoirs- HICs
-urbanisation- LICs
-transport- LICs
-timber- LICs
-logging- LICs
impacts of deforestation
-ecological impacts: reduced biodiversity, loss of species, fragmentation of remaining forest areas, loss of amenity
-impact on soil: reduced soil formation, less DOM, inc soil erosion, less protection of soil by vegetation & leaf litter, dec soil organic matter, dec root binding
-climate impacts: inc albedo, dec carbon sequestration & carbon reservoir, reduced rainfall downwind
-changes to hydrology: dec interception & transpiration, inc runoff
