Agriculture Flashcards
What does agriculture involve?
it involves the control of ecosystems o divert energy and nutrients into the human food chain
What are the key principles of agriculture?
Selection of species
Control of abiotic and biotic features
manipulation of food species to improve productivity
Why is a suitable temperature needed in agriculture?
Needs to be warm enough for growth
Some crops need frost-free periods
Evaporation impacts: higher temp=more water
Biochemical reactions are increased by higher temps
Keeping animals warm reduces heat loss so more energy is used in growth
What is the thermal growing season?
The season in which temperatures are warm enough to sustain growth
What species can grow in frost?
Raspberries are not affected by frost
How can temperature be controlled in agriculture?
Greenhouses, heated with solar or gas
Candles or large fans to disperse the cold air in orchids during frosts
Woven plastic cloth over fields to retain warm air close to the ground
Livestock kept warm by providing shelter or them being kept inside during the winter
Why else would livestock be taken in over the winter?
Lack of food as grass doesn’t grow in temperatures below 5 degrees
Why is light important in agriculture?
Light affects photosynthesis, therefore daylength affects photosynthesis
What is photoperiodism?
Daylength
What crops need longer days/more light?
Oats
What crops need shorter days/less light?
Maize
How are livestock affected by daylengths?
Long day lengths increase milk production.
Poultry grow best with short days but egg production is increased in longer days.
Sheep mate in shorter day lengths
How can lighting be controlled?
Artificial lighting to extend the growing season
Why is water important in agriculture?
A solvent for chemical reactions
Nutrients absorption
Cell water provides support
Water used to replace water lost in transpiration
Used for transport of minerals
Gaseous exchange
What is the hydrological growing season?
The time during the year that there is sufficient water to sustain growth
What crops have high water needs?
Rice needs flooded fields
What crops have low water needs?
Cereal crops like wheat
What happens to tomatoes in irregular rainfall?
Their skin expands and splits
What do humid conditions attract?
Fungal diseases
What problems are caused by waterlogged soils?
Higher risk of fungal diseases
Soils become anaerobic so mor denitrifying bacteria, less nitrogen in soils
How can waterlogged soils be reduced?
Drainage
Deep ploughing
Avoidance of soil compaction
Provision of conditions for worms
What are problems of water shortages?
Lack of water means crops close their stomata so no absorption of CO2, therefore no photosynthesis so plants stop growing.
Increases trampling by livestock as they have to travel further to find water which can lead to desertification and erosion
What methods can be used to increase water?
Drip irrigation
Soil mulching to reduce evaporation
Provision of conditions for worms for increased infiltration
Less compaction by less machinery or smaller stocking densities
Adding OM to increase water retention
What is soil fertility?
The ability of soil to sustain growth
What are the macronutrients plants need and what are they used for?
Nitrogen- protein
Phosphorus- ATP manufacture
Potassium- seed development
Calcium- cell walls
Magnesium- chlorophyll
Sulfur-protein
What are the micronutrients plants need and what are they used for?
Iron- chlorophyll
Zinc- enzyme activation
Copper-enzyme activation
What does crop rotation allow?
Gives time for weathering to release more nutrients
What are the advantages of organic fertiliser?
Are waste products so easy to find
Increase soil humus content
Increase soil biota populations
What are the disadvantages of organic fertiliser?
Nutrient composition cannot be controlled
Nutrients are released slowly and cannot be added to growing plants
Transport is spenny because they have a high water content
What are the advantages of chemical fertiliser?
Nutrient composition can be controlled
Nutrients are released rapidly and can be added to growing plants
What are the disadvantages of chemical fertiliser?
Reduce soil humus content
Reduce soil biota populations
Expensive to manufacture
Some are toxic to worms
Leaching is possible
Give some examples of organic fertiliser
Manure/sewage sludge
Composted plant waste
What are cultural methods used to apply fertiliser?
Natural methods like nitrogen fixation and weathering
What is hydroponics?
Growing crops in nutrient solution instead of soils
What are the advantages of hydroponics?
No soil to hold pathogens
Cleaner plants/roots so more attractive
Nutrient supply can be controlled
No weeds
What are the disadvantages of hydroponics?
Intensive production so expensive
A high level of knowledge is needed
How can aeration of soils be controlled?
Ploughing top layers of soil
Adding OM to provide nutrients for soil biota
Remove livestock from fields in wet conditions to stop compaction
What do different pH’s do to the soil and how can it be controlled?
Acidic soils increase leaching and decrease nutrient uptake, pH can be increased by adding crushed lime.
Alkaline soils decrease nutrient solubility, pH can be decreased by spreading powdered sulfur
How does topography affect agriculture?
Valleys are more exposed to sunlight so are warmer
Low lying areas are more susceptible to frost as cold dense air collects there
Steeper gradients increase runoff
Gentle gradients increase flooding
How can the topography be controlled?
Flat areas levelled so water drains slowly, this is good for growing rice.
Steep gradients may be terraced
What problems can wind velocity cause?
Increased soil erosion
Increased evaporation
Crop damage, they an be flattened
How can wind be controlled?
Hedgerows or wind breaks like rows of trees
How do pests harm livestocks?
Can be predators
Competitors
Be Pathogens or carry pathogens
What are endemic pests?
Pests that are always present but in small numbers
What are epidemic pests?
Pests that are not normally present but there can be outbreaks where they rapidly become a problem
What does cultural pest control involve?
Involves non-pesticide methods
How can crop rotation be used in cultural pest control?
Crop rotation involves growing different crops each year so that pests on the previous crop will die before that crop is grown again.
Every 4-5yrs
How can companion crops be used in cultural pest control?
Barrier crops- growing onions to mask the smell of carrots stopping carrot root fly.
Nutrient supply- intercropping legumes to provide more nitrogen
How can predator habitats be used in cultural pest control?
Increasing predator populations by providing suitable habitats, like beetle banks and hedgerows.
These are homes for ladybirds which eat aphids
How can biological control be used in cultural pest control?
Predator or pathogens may be introduced to control pests.
Give an example of successful biological control
The prickly pear cactus which was introduced to Australia from South America became overpopulated as it had no predators, the Cactoblastis moth was introduced from South America as a predator to the cactus.
Give an example of unsuccessful biological control
The cane toad was introduced as a predator to sugar cane pests but they ended up eating a range of other species, they are toxic so they have no predators.
Have to be killed by humans
How do sterile male techniques work in insects?
Males are exposed to gamma radiation so they become sterile.
Females only mate once so if they mate with a sterile male they wont produce any offspring.
When would sterile male techniques not work?
Female mosquitoes won’t mate with sterile males due to a change in their behaviour
How do pheromone traps work?
Pheromone traps release a scent attracting the pest.
They are used to detect the pest or to kill enough of one sex so there is not enough matings
What are the the characteristics of a good chemical pesticide?
High toxicity so smaller vol used
High specificity so less damage to non-target species
High persistence so reduced application, however the pesticide could be dispersed further
Why is it bad for chemical pesticides to be water soluble or liposoluble?
Water soluble will get washed off and have to be reapplied
Lipo soluble may be absorbed by the plant and could enter the human food chain
What is contact action?
Kill plants by damaging the plant tissues they are sprayed onto.
They will kill insects who come in contact with the plant or who are sprayed.
Unsprayed surfaces are not protected, and can be washed off by rain
What is systemic action?T
The pesticide is absorbed and translocated within the plant.
Protect the whole plant and any new growth.
This will kill any insect that sucks the sap from the plant
What are antibiotics used for in agriculture?
To treat infections
To prevent infection, done as a precaution in high stocking densities
To promote growth by increasing the amount of food energy used for growth.
How can livestock become resistance to antibiotics?
Low doses may only kill the most sensitive pathogens, this means the rest will develop resistance,
What are hormone pesticides and give an example
Kill through biochemical action, by increasing or starting natural processes early.
Can cause insects to grow into adults before theyre large enough which causes them to die.
What is integrated control?
Using a combination of techniques to control pests based on cost and effectiveness
How can pollinators be conserved?
Food provisions, growing flowering plants.
Restricting pesticides that harm pollinators
Introducing bee hives
What is produced by decomposition?
Organic acids which increase weathering of rocks which release nutrients into the soil.
How can population be controlled to manipulate food species?
Increasing population of livestock increases yield, however increases risk of disease
Growing monocultures so that cultivation is easier, however a disease outbreak will harm all crops
What are the advantages of asexual reproduction in plants?
Offspring are genetically identical, so predictable characteristics and high survival rate
What are the disadvantages of asexual reproduction in plants?
No genetic variation so characteristics cannot be improved.
Smaller yield
What is the method for cloning in animals?
Cells removed from donor and grown, an egg is removed from a female.
The nucleus of the egg is removed and is replaced by one from the donor cells.
The egg is implanted into a surrogate female, a pregnancy occurs and the offspring has the same characteristics as the donor.
Where might cloning be used?
An outbreak of disease in cattle can be replaced by genetically identical ones.
What are the methods used in breeding programmes in agriculture?
Selective breeding
Crossbreeding
Genetic modification
Artificial insemination
Embryo transfer
Give examples of selectively bred species
Highland cattle
Saddleback pig- good milkers and large litters
Cheviot sheep- resistant to foot rot and parasitic worms, wool free face so no wool blindness
Give an example of a crossbred species
Australian Zebu milking cattle, produced by breeding Zebu cattle who are heat tolerant with Ayrshire cattle who have high milk yield.
What does cross breeding involve?
Crossbreeding between two different breeds to produce characteristics with hybrid vigour
Describe the process of embryo transfer
FSH used to stimulate ovulation and the release of eggs.
Eggs are collected and fertilised by sperm, embryos are inserted into surrogate females. This means that the donor female is not harmed and more offspring can be produced
Give 2 examples of genetically modified crops
Roundup ready soya: bacteria resistant to the herbicide roundup introduced into soya so that it becomes resistant to the herbicide.
BT crops: Bt produces a toxin that kills pests this has been introduced into corn to protect it from insect pests
Oilseed rape/omega 3: Lack of seafood which contains omega 3, so omega 3 was taken from algae and transferred into rapeseed crops.
What are the advantages of GM
Individual characteristics can be introduced
Can increase pathogen resistance
Can increase resistance to pests/insects
What are the disadvantages of GM?
Increased allergies
Gene transfer from crop to body cells
GM pollen potentially transferred to wild crops
Increased cost to farmers in poorer countries
Potential of decreasing wild crop diversity
What is the law of diminishing returns?
Where each extra input will increase the yield but the size of each successive crop will be smaller
What are some agricultural energy subsidies?
Nitrate fertiliser manufacture
Pesticide manufacture
Pumping irrigation water
Fuel for machinery
Transport and processing food
What is the energy ratio?
A measure of efficiency in a system
How do you calculate energy efficiency?
Energy output/Energy input
The bigger the ratio the higher the yield
What is the food conversion ratio?
The amount of energy from food which is used in growth/ total energy
The lower the ratio the better
How do you calculate the food conversion ratio?
Mass of food/ mass of output or growth
How do you calculate efficiency?
Yield/input
How do you calculate productivity?
Yield/unit area
What type of agriculture could be used on land too salty/salt marshes?
Salt marsh sheep, this way some food is provided instead of none.
What animals could be used on high mountains?
Highland cattle
What are the habitat impacts of agriculture?
Habitat clearance
Drainage of the soil, decreases wetland species
Reduced biodiversity
Nutrient enrichment, taller grasses could outcompete smaller wildflower species
Soil erosion
What are some habitats created by agriculture?
Hedgerows
Hay meadows
Grazed moorland and heathland
Chalk grassland
What pollution does agriculture cause?
Pesticide pollution: not species specific, affects inter-species relationships if food species, pollinators etc are killed
Nutrient pollution: leached inorganic feO2rtilisers cause eutrophication, organic nutrients cause deoxygenation.
Nitrate toxicity: Nitrates can be leached into human water sources. Nitrates cause blue baby syndrome, and are potential carcinogens.
What farming activities release GH gases?
CO2- use of fossil fuels and ploughing which increases aerobic respiration
Methane- rice padi fields, livestock intestines, anaerobic digestion
NOx- nitrogen fertiliser
What is embodied energy?
Hidden energy, for example energy used for cultivating a crop, processing the crop, transporting the crop.
How does agriculture affect the hydrological cycle?
Irrigation depletes water sources
Soil erosion reduces water retention
Soil compaction increasing runoff and more river fluctuations
Transpiration decreased when crops are harvested
What social factors affect agriculture?
Cultural: type of meat eaten
Religious: Muslims dont eat pork
Ethical: vegan, buying seasonal foods, buying free range, buying organic, buying fairtrade food
What can GPS mapping, drones and satellites monitor in agriculture?
Rate of photosynthesis
Biomass estimation
Soil water content
Spread of pests/diseases
Area for birds or tree plantations
What can computer based monitoring be used for?
Can be used to better control fertiliser application, this maximises yield whilst lowering environmental impact and waste
After the war farmers were given grants for what projects?
Hedgerow removal to increase field size
Purchasing machinery
Buying livestock
Draining fields
What was the guaranteed market?
When there was a surplus in harvest the government would buy stock to create an artificial shortage this prevented financial loss for the farmers
What happened to the stock bought by the government?
Where possible the stock would be stored and would be sold when there was an actual shortage
Why did the guaranteed market become a problem?
As productivity increased there were more surpluses than shortages, the government couldn’t sell the food.
How were food surpluses reduced?
Quotas on what could be grown
Farm diversification: public visits, specialised farms like ice cream
Alternative crops: biofuels, pharmaceutical crops
Agri-environmental schemes: CSS,ESA , ESS, CS
What is the aim of extensive agriculture?
To maximise the total yield by spreading the inputs over a large area
What is the aim of intensive agriculture?
Where large inputs are spread over smaller areas of field
What are chemo-autotrophs?
Bacteria which harness energy by oxidising substances like methane or nitrites
What are some introduced pests in agriculture?
Tomato blight
Potato blight
How can you reduce methane in agriculture?
Feeding livestock a diet higher in carbohydrates
Cultivating rice varieties that can survive in drier conditions so fields can be drained
