Agriculture Flashcards
What are the key principles of agriculture?
Selection of species, control of abiotic and biotic factors and manipulation of the food species to improve productivity
What factors affect the choice of species for farming?
Market demand and access, within range of tolerance for the food species, if the environmental conditions can be controlled
What effect can temperature have on agriculture?
Frost-free period, thermoregulation(livestock), impact on evapotranspiration, biochemical reactions, length of thermal growth season
How is the temperature controlled in open fields?
Burning gas, oil and candles or by dispersing cold air with large fans, transparent woven plastic cloth and livestock can be kept warm by providing shelter or buildings, low lying areas (more likely to frost), south-facing slopes
How does light impact agriculture?
Rate of photosynthesis, wavelengths for different pigments and photoperiodism (day length)
How does photoperiodism affect livestock?
Poultry grow best with short days while egg production is greatest on longer days, long day length increases milk production and some livestock such as sheep mate when days are getting shorter in the autumn, with the lambs being born in the spring
What plants are affected by photoperiodism?
Oats require longer days for optimum growth, whereas maize requires shorter days for growth
How can light levels be controlled artificially?
Artificial lighting can be used to extend the growing period or encourage mating
How does water affect agriculture?
Gas exchange, physiological functions, nutrient absorption, turgidity, transport medium and replacing transpiration after losses
How can water supply affect crops?
Most rice varieties must be flooded during early growth, some cereal crops have low water requirement e.g. wheat, irregular water supply can cause crops to expand and split ad humid conditions can increase fungal diseases
What qualities of water can affect their growth?
Reliability, quality, high salt content, amount and heavy metals
What methods are used to reduce water levels in soil?
Deep ploughing, avoidance of soil compaction by machinery or livestock, excavation of drainage ditches and provide conditions to encourage worms
What are some of the issues caused by water shortages?
Livestock in semi-arid areas may die and may increase trampling if animals regularly have to walk longer distances, crops will close stomata to reduce water loss, but this limits photosynthesis
What methods can be used to increase water availability?
Crop irrigation, soil mulching to reduce evaporation losses, provision of suitable conditions for worms, reducing soil compaction and adding soil organic matter to increase water retentions and buffer strips
What are riparian buffer strips?
Buffer strips near water courses
What’s the difference between macronutrients and micronutrients?
Macro nutrients are need in much larger quantities
How does crop rotation affect nutrient availability?
Gives time for weathering to release more nutrients and to even out the demands for particular nutrients by different crops
What are some examples of organic fertilisers?
Faecal material, animal old production wastes and plant food production wastes
What are the advantages of inorganic and organic fertilisers?
Inorganic: Nutrient composition controlled to meet specific requirements, released rapidly
Organic: locally available, increase soil humus content and soil biota populations
What are the disadvantages of inorganic and organic nutrients?
Inorganic: Some require large amounts of energy in manufacture, do not add organic matter, some toxic to worms, some have high solubility and may leach, raw materials limited
Organic: Nutrient composition cannot be controlled, released slowly so must be used for long-term cultivation plan, expensive transport and they usually cannot be added to a growing crop
How are fertilisers applied?
A crop rotation cycle will add manure to the soil and mechanical application
What are green manures?
Crops grown specifically for building and maintaining soil fertility and structure
What is hydroponics?
Growth of crops in a nutrient solution rather than a solid growth medium, typically carried out in a greenhouse in an intensive system
What are the advantages of hydroponics?
Nutrient supply is optimal so not a limiting factor for growth, no soil to hold pathogens, no weeds, still has roots so stays fresher for longer, attractive to consumers
What are the disadvantages of hydroponics?
Intensive so high input of nutrients and energy and high level of ten chin cal knowledge needed
How is aeration naturally balanced?
Gravity causes compaction of the soil and this is counteracted by tunnelling action of detritivores
What increases soil compaction?
Weight fo farming machinery, livestock trampling, reduction in organic matter contents, shallower roots has less penetration so more compaction, ploughing can kill soil organisms
What can increase aeration?
Ploughing, adding organic matter, low tillage methods and removal of livestock
How can emoted form soil and what are the potential problems with this?
Extra water can be used to wash the salts out of the soil but this gently increases the water consumption and can cause ecological problems by increasing the salinity of the local river
What are the dangers of high and low pH?
High can inhibit nutrient solubility and low can increase the leaching of nutrients and inhibit nutrient uptake, it can also mobilise toxic ions such as aluminium an lead
How can pH of soil be increased?
Adding crushed lime and spreading powdered sulphur
How can topography affect agriculture?
Aspect, frost pockets, runoff rate and use of machinery
How can aspect affect topography?
Undulations e.g. valleys, produce some areas which are more exposed to sunlight
How do frost pockets affect topography?
Cold dense air tends to collect in low-lying areas, making crop frost damage more likely
How is the use of machinery affected by topography?
May be difficult to operates land that unrelated a lot or where gradients are very steep
How is topography controlled?
Terracing to create flat fields to retain irrigation water and reduce soil erosion, areas that are nearly flat may be levelled by machinery
How are livestock affected by altitude?
Cattle don’t thrive because the low atmospheric pressure causes ‘high altitude disease’, where pulmonary artery thicken
How are crops affected by altitude?
Temperatures are often colder at high latitudes, the low atmospheric pressure may increase the evaporations rates
What problems can wind velocity cause?
Increased evaporation rates and the drying of solid, crop damage and increased soil erosions
What are some examples of pests?
Insects, mites, nematodes, slugs/snails, rodents, birds and mammals
How do pests harm plants?
Eat the crop or livestock, reduce marketability for example spoiling view, be or carry pathogens that cause disease and compete for resources such as water or nutrients
What are endemic pests?
Always present, usually in small or moderate numbers
What are epidemic pests?
Not normally present but there may be ‘outbreaks’ where rapidly become a major problem
What are epidemic pests?
Not normally present but there may be ‘outbreaks’ where rapidly become a major problem
What is cultural pest control?
Cultural pest control involves non-pesticide methods where crops or livestock are cultivated in a way that reduces the risk
What are the benefits of crop rotation?
Maintain nutrient levels or allow them to recover as well as stopping the pests from returning early in the season and allowing them to build populations
What’s an example of companion crops?
Alyssum can attract wasps ad hoverflies which eat black fly high can destroy crops
What are barrier crops?
Crops that deter to prevent pests e.g. the smell of onions can mask the smell of carrots
How can predator habitats help pest control?
Populations of natural pest predators can be increased by providing suitable habitats, beetle banks and hedgerows give hibernation and food supply to pest predators such as lady bugs and black ground beetles that eat aphids
What is a successful example of biological corridors?
Prickly Pear cactus as introduced from South America to Australia where it had no predators and spread rapidly over large areas of farmland, it was controlled by introducing the Cactoblastis moth from South America, they are both now rare
What is an unsuccessful example of biological corridor use?
Cane toads were introduce to Australia to control beetle pests of sugar cane but they have eaten a wide range of other species, they are toxic so they have few predators and have colonised a huge area
How does sterile male techniques help pest control?
In many insect species, the females only mate once then store sperm for all future egg laying, if a female mates with a sterile male hen she will never produce any offspring
How are male pests sterilised?
Exposing them to gamma radiation
What are some disadvantages fo male sterilisation?
Only successful if the sterilised males behave normally and succeed in finding mates, may later mating behaviour so mating won’t happen, re-colonisation from nearby areas that have not been cleared may require regular re-treatment
What are some methods of pest control?
Pheromone traps, male sterilisation, pesticides, introduction of predator species, barrier crops
How can pheromone traps be helpful?
Show that the pest is present so that pesticides can be used to protect the crop, kills all the pest individuals of one gender to slow the matings
What are some organisms that have been selectively bred?
Chickens, cattle, pigs and sheep
Broccoli, cauliflower and cabbage all come from the wild mustard plant
How are pesticides impacted by the mode of action?
Contact pesticides harm tissue or insets they come into contact with and can be washed off by the rain and limits human exposure
Systemic pesticides are trans located through the plant to protect from pests that ingest the plant
How are antibiotics used in agriculture?
Prevent infection, treat infections and promote growth
Antibiotics reduce the population of non-pathogenic gut bacteria, this can increase the amount of the animals food that is used for growth, therefore increasing productivity
What is growth gross efficiency?
The ratio between growth rate and food consumption
What’s the potential problem with antibiotic use?
Increases antibiotic resistant bacteria and some may be zoonoses, which cause disease if they are transferred to humans for example E.coli
How do hormone pesticides harm insects?
Cause growth and development in a way that will cause death, some cause metamorphose into adult before they’re big enough, other prevent chitin skeleton formation
What’s the benefit of hormone pesticide?
Low persistence and more specific
What are the principals of integrated control?
Make the environment less suitable (maintaining habitats for indigenous predator), preventing build-up (crop-rotation), essential use only, non-pesticide techniques, cultivating species that are less likely to suffer
What are the advantages and disadvantages of asexual reproduction of plants?
Adv: high survival rate and predictable
Dis: no genetic variation so no improvement and fewer offspring
What are the potential benefits of cloning in agriculture?
Valuable animals can be replaced, herds that are culled during a disease outbreak can e replaced and large numbers of individuals with desirable characteristics can be produced
How has the highland cow been selectively bred?
Even temper, few stress problem and hardy
What are the benefits of cross breeding?
May produce a combination of desirable characteristics with ‘hybrid vigour’ and a lower risk of inbreeding
What’s an example of cross breeding in agriculture?
Zebu cattle tolerate heat but little milk yield an Ayrshire cattle give high yield but little heat tolerance, cross breeding has created a hybrid vigour
What is genetic modification beneficial?
Allows the introduction of a single characteristic from one species to another, or between varieties or breeds of the same species
Why had GM not become commercially cultivated?
Environmental and human health concerns
What are Bt crops?
Crops that have had the Bacillus thuringiensis gene transferred into them, this gene from the bacteria secretes a toxin to most insects so has protected crops such as corn, cotton and maize
How has GM increased supplies of omega-3 fatty acids?
The gene for production has been transferred form marine algae into oil seed rape
What are the advantages of GM?
Marketability, increased pathogen resistance, reduced need for pesticides, only move desirable characteristics, food security even though GCC, less land demand when density increases, longer growing season, increased gene pool, new foods and longer shelf life
What are the disadvantages of GM?
Unknown impacts on human health, food chain transfer, lower fertility of offspring, social responsibility and ethics, triggered allergies, decrease local crop variety, public opposition, Bt can get into soil and decrease fertility and concerns in LEDCs that GM crops will reduce local indigenous crop diversity
What is extensive agriculture?
Aims to maximise the total yield by spreading the available inputs over a large area of available land
What is intensive agriculture?
Large inputs are available but there may be a shortage of land and it is labour intensive
Where is energy used in agriculture?
Machinery (ploughers and tractors), labour, transportation, heating of barns, storage facilities
What is the food conversion ratio?
A measure of the mass of food needed to produce a given mass of livestock growth, the lower the ratio, the better the conversion of food into animal biomass
What are chemoautotrophs and what do they do?
Bacteria that harness energy by oxidising substances such as hydrogen sulphide, methane and ions of ammonium and nitrite
What are the environmental impacts of agriculture?
Habitat clearance, wetland drainage, ploughing of grassland, reduced biodiversity, genetic contamination, soil degradation and erosion, pesticides, nutrient pollution, GHGs, unsustainable irrigation and changes in evapotranspiration
What are some created habitats through agriculture?
Hedgerows, grazed moorlands, heathlands and hay meadows
How are indigenous species impacted by agriculture?
Many will not be able to survive in the new conditions or will be eradicated because they ar predators or competitors
How does nutrient enrichment impact agriculture?
Using fertilisers increases nutrient availability and plant growth rates, species that respond by growing taller e.g. grasses may outcompete smaller plants e.g. wildflowers
how does agriculture release carbon dioxide?
Burning fossil fuels in machinery and aerobic conditions in the soil created leads to more aerobic respiration from organisms releasing CO2
How does agriculture increase the release of nitrous oxides?
Nitrogen fertilisers lead to NO3 being released through evaporation and manure and urine releasing ammonia which can be oxidised into nitrite and then nitrate
How does agriculture release methane?
Livestock intestines, rice paid fields and anaerobic digestion by microbes
How is embodied energy impacting agriculture?
The manufacturer of materials, especially nitrate fertilisers, and machinery, usually involved he use fo many fossil fuels and causes the release of GHGs
How does agriculture impact the hydrological cycle?
Soil erosion reduces effect of water retention and moderation of river flow, irrigation depletes sources, changing evapotranspiration (varies), soil compaction can increase runoff rates and cause more rapid fluctuation in river flow
How does consumer choice influence agriculture?
Social factors, cultural factors, religious factors and ethical factors
What economic factors can influence agriculture?
Subsidies, guaranteed prices and quotas
What political factors can influence agriculture?
Trade controls, economic controls, subsidies, guaranteed prices and quotas
What ethical issues may one consider that impacts agriculture?
Local food (food miles), seasonal eating, free-range livestock, organic food, fair trade
How does technology impact agriculture?
Machinery and equipment for activities such as ploughing, sowing, spraying, harvesting, spreading agrochemicals and irrigation, pesticides, fertilisers, genetic improvements through breeding programmes, support infrastructure such as transport systems, refrigeration and food processing
What technology is used for surveying?
GPS mapping and the use of drone and satellite technology
What is survey technology used to measure?
Rates of photosynthesis, biomass estimation, spreading of pests and diseases, soil water content and cropped area of fields, area of cover for wild birds and tree plantations and other things
When were agricultural grants put in place?
After the WW2 farmers couldn’t afford to invest in high productivity methods, grants were used for purchase of machinery, drainage of wetlands, liming to neutralise acidic soils, hedgerow removal, to increase field size and improve livestock
What was guaranteed market?
Surplus food would be bought by the government so that demand would stay for farmers to make profit, some would be stored but fruits and veg would be destroyed, if there was a poor harvest, stored food would be sold to prevent price rise, when the food store got too high there was nothing to do with them as other countries had the same schemes and poorer countries couldn’t afford to pay and selling cheap would hurt farmers
What methods were used for reducing food surpluses?
Quotas, alternative crops and livestock(biofuels/pharmaceuticals), farm diversification(new products and non-food productionbrecreationbspecialised airy production) and set-aside
What are some strategies to increase agriculture sustainability?
Pest control, reduced use of chemical pesticides, reduced use of antibiotics, cultural pest control, integrated control, nutrient supplies natural processes, low tillage, waste management and management of social impacts
How can methane emissions be controlled?
Feeding cattle high carbohydrate deists and grinding their food first reduces methane
How is wildlife maintained by agriculture?
Maintaining natural and semi natural habitats e.g. hedgerows, ditches, ponds and woodlands, providing correct conditions for soil biota and reducing impacts of rural ecosystems and communities
How is the gene pool of species protected?
Conservation of habitats to protect CWR and seed banks to conserve biodiversity
What are the cultural pest control methods?
Crop-rotation, companion crops, predator habitats, biological control, sterile male techniques, pheromone traps, genetic resistance to disease and GM crops and pest control
What biotic factors need to be controlled in agriculture?
Pest control, pollinators and maintenance of soil biota
