Agriculture Flashcards
Principles of Agriculture
Selection of species, control of the environment (abiotic and biotic conditions), manipulation of species
Autotrophic nutrition
where organisms make their own food using inorganic substances like water, carbon dioxide, and mineral salts. In agriculture we are only interested in photosynthesizers
Photosynthesis equation
6CO2 + 6H2O → C6H12O6 + 6O2 (with sunlight over the arrow)
Heterotrophic nutrition
a method of obtaining food by consuming other organisms
Abiotic factors in agriculture
Temperature, Light availability, Water availability, Nutrient availability, pH, wind velocity, Soil air, CO2, Salinity
Importance of temperature
Affects rate of photosynthesis, length of growing season, rate of biochemical reactions, rate of evaporation of water, thermoregulation in animals
Control of temperature
Animal stocking densities, use of greenhouses/polytunnels, heaters, ventilation, soil and individual plant insulation
Importance of light
Photosynthesis, long day length for milk production, short day length for poultry growth, long day length for egg production, short day length for sheep mating.
Control of light
Artificial lighting (usually indoors)
Importance of water
Essential for photosynthesis, nutrient transport, turgidity, solvent for nutrients, oxygen and glucose, replacement of water lost due to transpiration
Reduction of water
drainage, ditches, deep ploughing, aerating soil, encourage worms
Increasing water availability
Irrigation, mulch to reduce evaporation, addition of organic matter to hold onto water, avoiding soil compaction to increase infiltration
Importance of nutrients
Required for general health, production of essential living components, and growth
Macronutrients
Nutrients required in large amounts eg NPK
Micronutrients
Nutrients required in smaller amounts eg Ca, Cu, MG, S, Fe, Zn
Inorganic control of nutrients
Addition of synthetic fertilisers containing mostly NPK
Organic control of nutrients
addition of faecal matter eg manure, sewage sludge. Addition of food production waste eg blood, bone meal, fish meal. Addition of composted plant/food waste
Importance of soil air
Aerobic processes include root respiration, nitrogen fixation and decomposition
Control of soil air
Ploughing, adding organic matter, encouraging worms, rotating livestock and feeding stations to avoid compaction
Control of salinity
addition of water to dilute salts
Problems caused by wind
crop damage, increased soil erosion, increased evaporation
Control of wind velocity
natural and artificial windbreaks, hedgerows, drystone walls, fencing, rows of trees
Importance of Carbon DIoxide
essential for photosynthesis, only becomes a limiting factor in enclosed conditions
Control of Carbon Dioxide
ventilation, combustion of a fossil fuel
Biotic factors in agriculture
Pests, predators, disease, pollinators, soil biota
How do pests reduce productivity?
Competition (for…), predate upon or consume the product, disease vector, reduce value/marketability.
Endemic pests
pests that are usually always present in low numbers
Epidemic pests
pests that are not usually present but can appear infrequently as outbreaks
Indigenous pests
pests that are native to an area
Introduced pests
pests that are not native to an area that may have been introduced accidentally, intentionally or migrated due to climate change.
Cultural pest control
non chemical pest control methods often utilising natural ecosystem services
Examples of cultural pest control
crop rotation, companion crops, biological control, mulching, predator habitats, culling, weeding, barrier crops
Crop rotation
the movement of crops to different areas/fields every year to reduce the presence of pest or disease, can include a fallow field
Fallow (field)
a field that is left uncultivated for a period of time so the soil can recover and replenish nutrients (also reduces the establishment of pests/disease)
Companion crops
These are crops that are grown together to benefit one or both crops by actions such as providing nutrients, controlling pests or attracting beneficial insects.
Predator habitats
the provision of a habitat to encourage the colonisation of a biological controller such as beetle banks.
Biological control
The control of pests using living organisms, usually predators or pathogens.
Barrier crops
A crop that is grown around another crop to protect the neighbouring crop, usually by producing a scent that deters the pests.
Pheromone
A chemical released by an organism that changes the behaviour of other members of the same species, especially to attract a mate.
Pheromone trap
A trap that attracts organisms using the scent of pheromones. They can be used to try to catch all the members of one gender of a species to stop breeding, but are usually used to show the presence of a pest species.
Sterile male techniques
A method of insect pest control that uses the release of males that have been sterilised (using gamma radiation). If they mate, no offspring will be produced (most females insects only mate once)
Integrated control
A method of controlling pests in an order that utilises cultural pest control methods before the use of chemical pesticides
The principles of cultural pest control, the order of pest control selection
1 Cultural methods that make the environmental less suitable for pests
2 Cultural methods that help avoid the build up of pest
3 Choosing species less likely to be attacked by pests
4 Use of other non-pesticide techniques
5 use of chemical pesticides where essential
Properties of pesticides
toxicity, persistence, specificity, lipo/water solubility, bioaccumulation/magnification
Contact action (pesticide)
A pesticide that kills pests by coming in contact with them after spraying. Unlike systemic pesticides, they are not absorbed and translocated around the crops.
Systemic
A substance that is absorbed and transported throughout an organism eg by sap in plants.
Use of antibiotics in agriculture
1 treat infection/kill bacteria
2 prevent infection
3 promote growth by reducing gut bacteria that may use energy/calories
Problems with antibiotic use
low doses may only kill sensitive bacteria and the surviving population may become antibiotic resistant and difficult to control in the future
Hormone pesticides
Does not kill by being toxic, hormone pesticides trigger a life stage that the individual is not ready for, for example early moulting of skeleton or early metamorphosis into an adult that then makes them unable to survive. These pesticides are usually very specific to a particular pest
Organochlorines
Hydrocarbon-based compounds that include chlorine. They include pesticides such as DDT and industrial chemicals such as PCBs. Their use is now banned or restricted. High toxicity to insects, low toxicity to mammals, high persistence, liposoluble (bioaccumulation and magnification). DDT use led to the decline of the golden eagle.
Organophosphates
Insecticide group e.g. parathion, malathion. They are not persistent but have high mammalian toxicity. They are neurotoxins that damage nerve function. Sarin is an organophosphate developed as a weapon in WWII. Long term (chronic) exposure at low doses can cause ADHD, Alzheimers, memory problems, depression, and may also be carcinogenic.
Pyrethroids
Synthetic insecticide pesticides, based on the natural chemicals originally extracted from chrysanthemum flowers (pyrethrins). They are not persistent and have low mammalian toxicity, toxic to fish.
Neonicotinoids
A widely used group of insecticides. They have been linked with the deaths of bees, especially when they act synergistically with some fungicides.
Population density in agriculture
Optimum population density depends on the abiotic and biotic factors of each farm as well as available inputs. High population density increases the yield but has increased risk of disease.
Monoculture
The growth of a single type of crop, usually over a large area.
Legumes
Plants with symbiotic nitrogen fixing bacteria in root nodules eg peas and beans.
Permaculture
An agricultural system that incorporates the principles of natural ecosystems.
Polyculture
An agriculture/aquaculture system involving the growth of more than one species in the same area at the same time.
Strip cropping
The growth of more than one crop in alternating narrow strips, so that different sowing and harvesting times reduce soil erosion because the whole field is never all bare at the same time.
Topography
The 3D shape of the land surface.
Asexual reproduction
reproduction whereby a new offspring is produced by a single parent. The offspring produced are genetically and physically identical to each other, i.e. they are the clones of their parents
Advantages of asexual reproduction in plants
offspring genetically identical to parents therefore characteristics predictable and easy to manage
Disadvantages of asexual reproduction
no genetic variation so characteristics cannot be improved. All susceptible to to the same disease or change in environmental conditions
Vegetative propagation
Asexual reproduction in plants in which a new plant grows from a fragment or cutting of the parent plant
Natural methods of asexual reproduction in plants
A genetically identical plant is produced via the leaf, stem or root
Cloning
An artificial form of asexual reproduction for livestock the produces a genetically identical offspring to one parent
Process of cloning
1 Cells removed from the parent and grown in culture stimulated by an electric shock.
2 Egg removed from a female.
3 Nucleus of the egg is removed and replaced with the parent cells.
4 Egg implanted into a surrogate female.
Benefits of cloning in agriculture
Valuable animals replaced by a genetically identical individual. Diseased or culled animals can be replaced. Large numbers of desired individuals can be produced
Selective breeding
Parents selected with desirable characteristics to produce offspring that also express those characteristics.
Crossbreeding
producing offspring from different breeds or varieties of the same species to produce offspring with hybrid vigour
Hybrid vigour
when the offspring of two different varieties/breeds of an organism is more fit or vigorous than either of its parents
Artificial insemination
semen is collected from a chosen male to be inserted artificially into the chosen female. Semen can also be stored for later use or transport without having to bring the animals together.
Embryo transfer
The transfer of fertilised eggs or embryos from one female to another, such as from a rare species into a female of a closely related species that is more common. This enables more young to be produced than could be achieved through normal breeding. It is also used in livestock breeding.
Genetic engineering/genetic modification (GM)
The method of altering an organism’s genetic makeup by artificially introducing genes from another organism, often of another species.
Transgenics
The process of artificially transferring genetic material from one organism into an individual of another species.
Advantages of genetic engineering
Introduces a single positive characteristic from one organism to another without the introduction of undesirable ones as may happen with selective breeding, genes can be introduced from organisms that could never be achieved by normal selective breeding.
Disadvantages of genetic engineering
Increased food allergies?, Gene transfer in the gastrointestinal tract, migration/escape of genes to non GM crops, antibiotic resistance as antibiotic resistant genes are often used as markers, cost to farmers, reduction in natural crop diversity
Gibberellins
A group of plant hormones that can encourage seed germination, growth and fruit production
Auxins
A plant hormone that can be used to encourage rooting in cuttings and for the production of seedless fruit.
Ethylene
A plant hormone that is used to encourage ripening
Anabolic steroids
administered to livestock to promote muscle growth/meat production
BST
Bovine somatotropin also known as bovine growth hormone, given to dairy cows to increase milk production
Intensive agriculture/aquaculture
where the yield is achieved with high levels of inputs. Productivity is usually high (yield per unit area) but efficiency is usually low (yield per unit input).
Extensive agriculture/aquaculture
where the yield is achieved with low levels of inputs, often over a large area. Productivity is usually low (yield per unit area) but efficiency is usually high (yield per unit input).
Productivity
A measure of the yield of a system, often expressed as the yield per unit area, time or input.
Efficiency in agriculture
A measure of the amount of output produced compared to inputs, more efficient “produces more with less”
Energy subsidies/inputs
Labour, energy, fuel, soil, water, nutrients, pesticides, fertilisers,
Law of diminishing returns
A law that states that as inputs are increased the rate of increase in outputs or yield reduces. Eg more fertiliser increases yield but each extra unit of fertiliser doesn’t produce the same increase as the previous.
Energy ratio
Outputs divided by inputs. A larger energy ratio is better in terms of efficiency.
Food conversion ratios (FCRs)
A measure of the efficiency with which an organism converts its food into its own increasing biomass. FCR = mass of food needed to produce one unit of new tissue. The lower the number the better - more out for less in
Environmental impacts of agriculture
loss of habitat, lower biodiversity, pesticides pollution, organic nutrient pollution, inorganic nutrient pollution, invasive species, soil erosion, water use, energy use (climate change)
Soil erosion
revise all of soils, it is part of agriculture!
Social factors that affect agriculture
Cultural factors e.g. horsemeat. Religious factors eg pork and beef. Ethical factors eg food miles, seasonal, free range, organic, fairtrade.
Economic and political influences of agriculture
Agri-Environmental Schemes, Grants, Food aid, The Marshall Plan, Subsidies, Import taxes, Guaranteed markets
Food aid
The provision of grants and low cost loans to increase food production
The Marshall Plan
officially the European Recovery Program, ERP, an American initiative to provide foreign aid to Western Europe after World War II. Grants provided to modernize industry, improve European prosperity and prevent the spread of communism, whilst also encouraging an increase in productivity and an adoption of modern business procedures
Guaranteed markets
providing an agreed minimum price or deficit payment where the value of produce falls below an agreed market price - provides financial security for growing products that may not have a stable market or require investment.
Agri-environmental scheme
contributing to a farmers income for carrying environmentally beneficial activities
UK agri-environmental schemes administered by Natural England
Countryside Stewardship, Environmental Stewardship, Sustainable Stewardship.
Managing Food surpluses
Quotas, Set-aside, Agri-environmental schemes, grants for farm diversification
Set aside
Farmers paid for taking fields out of production but maintaining them for food production if needed in the future
Quotas
Limits on the amount of food that can be produced and sold
How can agriculture be more sustainable?
This is a whole essay question, think of all the negative impacts of farming and discuss sustainable alternatives
Hydroponics
the growth of plants in a nutrient rich solution rather than soil
Advantages of hydroponics
control of nutrients, improved uptake of nutrients via roots, no pathogens (in soil), no weeds
Disadvantages of hydroponics
Intensive, high energy consumption, high level of technical expertise required
