Artificial Control Of The Environment Flashcards
What is a limiting factor in agriculture
Any condition or resource that restricts the growth and productivity of crops or livestock
Biotic factors that may affect food production
Disease
Pests
Pollinators
Weeds
Abiotic factors that may affect food production
Temperature
Soil pH
Water availability
Light availability humidity
Nutrient availability
Why would you want to manipulate temperature
Promote photosynthesis
Increase length of growing season
Avoid frost
Control evaporation rates
Examples of how temperature can be manipulated
Greenhouses
Polytunnels
Ventilation
Why would you want to manipulate light
Photosynthesis
Trigger animal breeding/day length
Longer day length - increased milk production
Examples of how light can be manipulated
Removing or adding lights
Why would you want to manipulate carbon dioxide
Photosynthesis
Examples of how carbon dioxide can be manipulated artificially
Buy CO2 canisters - pump into enclosed spaces
Burn fossil fuels
Why is water important for plants
Photosynthesis
Nutrients go into solution - taken up by plants
Turgidity in plants
Why is too little water a problem
Lack of gas exchange
Lack of nutrient uptake
Lack of photosynthesis
What can be done to improve to little water
Irrigation methods
Mulching
Drought resistant crops
Terracing
Tide ridging
Why is too much water a problem
Roots become waterlogged
Lack of gas exchange
Soil biota - anaerobic
Soil erosion
What can be done to improve too much water
Drip irrigation
Improved drainage systems
Cover crops
Addition of sand - increases drainage
Why would you want to manipulate wind velocity and what are the benefits
Prevent soil erosion
Reduce crop damage
Increase rate of evaporation - reduce water losses
Benefits:
Seed dispersal
Dispersal of disease
Dispersal of pollen
Examples of how wind velocity can be reduced
Windows
Rows of trees
Cover crops
Windbreakers
Multicropping
What do we mean by nutrients
A substance that provides nourishment
Different nutrients are required for different biological processes
What are macronutrients
Nutrients that are needed in larger amounts
E.g. nitrogen
Function of nitrogen in the plant
Protein synthesis
Nitrogen cycle
Form that plants absorb nitrogen
Ammonium ions
Nitrates, nitrites
Function of phosphorus in the plant
Used in ATP for photosynthesis
Cell division
Energy transfer
Form that plants absorb phosphorus
Dehydrogen phosphate
Function of potassium in the plant
Movement of water and nutrients
Enzyme activation
Form that plants absorb potassium
K+
What are micronutrients
Nutrients required in small amounts
Description of a natural fertiliser
Breakdown of organic material which releases nutrients
Examples of natural fertilisers
Manure
Sewage sludge
Advantages of natural fertilisers
Nutrient rich
Reduce chemical runoff
Increase soil biota
Disadvantages of natural fertilisers
Slower release
Odour issues
Pest attraction
Description of artificial fertilisers
Haber process
Anthropogenic
Examples of artificial fertilisers
NPK
Advantages of artificial fertilisers
High nutrient concentration
Consistent
Easy to apply - control release
Disadvantages of artificial fertilisers
Soil degradation
Water pollution - eutrophication
Dependency
Description of nitrogen fixation
Converts atmospheric nitrogen into nitrates, nitrites
Planting legumes - encourage nitrogen fixing bacteria
Description of crop rotation
Continuous movement of crops within different fields in different years
Leaving one field fallow
Why would you want to manipulate pH
Effects contents of heavy metas
Range of tolerance for plants
Problem with low pH and hat to do to correct it
Dissolving of heavy metals
Plant tissue break down
Adding crushed limestone
Problem with high pH and what to do to correct it
Essential nutrients wont go into soil - can’t enter the tissue
Adding sulphur
How can pests damage crops and livestock
Disease vector
Consume valuable crops
Cause stress to livestock
Increase competition for space etc
What types of agricultural practices are particularly susceptible to attack from pests
Monocultures
High density cropping
Major pest groups and examples
Insects - Aphids
Molluscs - Garden snail
Birds - Pigeons
Definition of Endemic and an example
Native organisms that consistently exist in a specific area
Example: Fox
Definition of Epidemic and an example
Pests that suddenly increase in population, causing widespread damage
Example: Locusts plague
Definition of Indigenous and an example
Native species that have evolved in a specific region
Example: Native grasshopper
Definition of Introduced and an example
Non-native species that have been brought into a new environment, either intentionally or accidentally
Example: New Zealand flat worm
How can we control pests
Parasitic wasp - biological control
Crop rotation - cultural control
Hand-picking - mechanical control
Explanation and benefits of weeding
Removal of weeds
+
Reduce competition
Improve soil health
Explanation and benefits of mulching
Add DOM to the soil
So weeds can’t get there
+
Increase nutrients
Improve aesthetic value
Explanation and benefits of crop rotation
Movement of crops to different fields in different years
+
Constant cycle of nutrients
Reduce soil erosion
Explanation and benefits of barrier controls
Plant deterrent crop
+
Provides protection to crops
Explanation and benefits of culling
Killing of species
+
Maintain population sizes
Disease control
Explanation and benefits of biological control
Using a species to kill pests
+
Maintain population of pests
Enhances biodiversity
Explanation and benefits of predator habitats
Encourage biological controllers
+
Increase biodiversity
Improve soil health
Explanation and benefits of intergrated control
Combining many methods
+
Cost-effective
Increased biodiversity
Explanation and benefits of polyculture/companion crops
Lots of crops in one area
Prevents one crop becoming dominant
+
Increase biodiversity
Improve soil health
Increase yield
What are the newer methods of pest control without pesticides
Pheromone trap
Animal hormones
Disease introduction
Sterile-male techniques
Explanation and benefits of pheromone traps
Hormone given off to attract a mate
Gather pheromone in a trap to attract pests
+
decrease damage to agriculture
Explanation and benefits of animal hormones
Trigger significant part of the life-cycle
Trigger something to happen too soon - organism cannot survive
+
Targeted control
Decrease chemical use
Explanation and benefits of disease introduction
Introduce disease that’s specific to the pest
+
improve crop health
Explanation and benefits of sterile-male techniques
Expose males to ionizing radiation
Female insects can mate once but don’t produce any young
Properties of chemical pesticides
Toxicity
Specificity
Persistent
Solubility
Explain the difference between contact and systemic chemical pesticides
Contact - sprayed on organism, sits on the outer layer - toxic to the organisms that consumes the sprayed organism
Systemic - applied to the soil, taken up by the tissue of the plants
How can pesticides be applied
Solid - goes into solution when it rains
Liquid - sprayed - systemic or contact
Gas - bug bomb, slug pellets
