Agriculture Flashcards
What are the key principles of Agirculture?
Selection of species, control of biotic and abiotic factors, manipulation of food speces
What 3 factors does selection of species for agriculture depend on?
Market demand, environmental conditions, controllability of conditions or adaptations
What is the importance of temperature in agriculture
- Thermal growing season
- Some crops are damaged by frost
- Higher temperature increases water need due to evapotranspiration
- Biogeochemical processes often happen faster in higher temps
- Mammals and birds use food energy to maintain body temp, less is needed if temp is kept high
How can we control temperature in agriculture?
- Low-lying areas are more likely to have frost
- Southern facing slopes in the north and North facing in the south receive more solar insolation
- Greenhouses
- Burning or dispersing cold air
- Shelter buildings for livestock
What is the importance of light in agriculture?
- Photosynthesis
- Day length can affect crop growth
- Day length can affect livestock reproductive function like long days increasing milk production and sheep mating during shorter days
How can we control light in agriculture?
Artificial lighting can be used to extend growing season or to artificially shorten day length to trigger livestock behaviours
What is the importance of water in agriculture?
- Water is the physiological solvent for all life
- Nutrient absorption takes ions from water
- Cell water increases turgidity
- Water is used for mineral transport
- Gaseous exchange stops if too much water is lost
- Humidity increases fungal infection risk
- Irregular water supplies can cause crops to split
What problems can be caused by waterlogged soils, how can waterlogging be prevented?
Problems:
- Fungal disease risk
- Anaerobic soil that encourages denitrifying bacteria that reduce fertility
Solutions:
- Drainage methods like ditches and pipes
- Avoiding soil compaction
- Encourage worms with soil organic matter
What problems can be caused by water shortages, how can water shortages be prevented?
Problems:
- Plants close stomata, preventing gaseous exchange, stopping growth
- Cell dehydration in crops
- Increased erosion/desertification if livestock have to travel further for water
- Dead livestock
Solutions:
- Crop irrigation
- Soil mulching
- Reducing compaction
What are the features of Soil Fertility?
- Nutrients
- Aeration
- Salinity
- pH
What are macronutrients and micronutrients? Give an example of each.
A macronutrient is a nutrient needed in large amounts such as nitrogen, phosphorus, or calcium.
A micronutrient is a nutrient needed in smaller amounts, such as iron, zinc and copper
What natural processes can make nutrients available?
- Legume’s nitrogen fixing bacteria
- free-living soil bacteria
- crop rotation/multiculture
What are the advantages of Organic Fertiliser?
- Locally available
- Increase soil humus
- Increases soil biota
What are the disadvantages of Organic Fertiliser
- Nutrient composition cannot be controlled
- Slow release
- Bulky and high water content means difficult transport
- Usually cannot be added to a growing crop
What are the advantages of Inorganic Fertiliser?
- Nutrient composition can be controlled
- Rapid release
What is Hydroponics?
The growth of crops in a nutrient solution as opposed to soil, usually in a greenhouse, so that production can be maximised by controlling limiting factors
What is Aeration?
A measurement of the space between soil particles which allows aerobic processes to happen in the soil.
How can aeration be affected by agriculture?
- Farm machinery or livestock can compact soil
- Farming methods can reduce soil organic matter and therefore aeration caused by worms
- Crops have shallow roots unlike trees, so more compaction deep
- Ploughing can push soil organisms deep enough that they cannot survive
How can we control agricultural effects on aeration?
- Low tillage or ploughing techniques
- Adding soil organic matter
- Removing livestock and heavy machinery during wet seasons
How can we control soil salinity?
Avoiding saltwater irrigation and increasing freshwater irrigation on saline fields
How can a high soil pH effect crops?
It can inhibit nutrient solubility
How can a low soil pH effect crops?
It can increase leaching of nutrients as well as mobilising toxic ions like lead.
How can we control soil pH?
Increased by adding crushed lime.
Decreased by spreading powdered sulfur.
How can Carbon Dioxide levels be controlled?
The burning of Fossil Fuels inside greenhouses, outside it is neither practical nor economic.
What 3 key aspects of Topography can effect crops?
- Aspect, which are undulations such as valleys that produce variation in sun exposure and warmth
- Frost Pockets, where cold and dense air collects making frost damage more likely
- Runoff Rate, steeper gradients make surface runoff more likely while flatter ones increase flood risk
How can the effects of Topography be limited or controlled?
- Terracing can be used to mitigate steep gradients
- Areas can be levelled to decrease water drainage rates
What is relief?
The altitude of an area
How can relief affect agriculture?
- Higher areas are colder, worse for crops
- Lower atmospheric pressure increases evaporation rate
- Some species are more or less adapted to higher reliefs
What agricultural issues can be caused by high Wind Velocity
- Increased soil erosion
- Increased evaporation
- Strong winds cause crop damage
How can wind velocity be controlled?
Hedgerows or other wind breaks
How can pests reduce productivity or quality?
- Predation of crop/livestock
- Compete against crop/livestock
- Be or carry pathogens
What are endemic and epidemic pests?
Endemic are always present in small or moderate numbers.
Epidemic are not normally present, but come in huge outbreaks
Why are introduced pests usually more of an issue?
They may not have any predators in the new area and local crops/livestock won’t be adapted against them
What is cultural pest control? Give some methods
non-pesticide methods that reduces risk of pest damage
- Crop Rotation
- Companion Crops
- Predator Habitats
- Biological Control
- Male Sterilisation
- Pheromone traps
- GM crops
How can pollinator services be aided?
- Provision of food supplies by growing nectar-high plants amongst crops
- Restricting pesticides that may harm pollinators
- Introducing bee hives or other pollinator homes
Why is Soil Biota maintenance important?
They increase nutrient availability by breaking down dead organic matter as well as increasing aeration and drainage
What 2 ways can food species be manipulated?
Population control and Genetic control
What is an optimum density?
The number of food species in a population where increasing the number anymore would be uneconomic.
Why is population density important?
High populations are more at risk from disease although overall yield increases. Individual yield decreases as population increases.
What benefit does a monoculture have?
Easier cultivation as machinery can be used
What drawbacks do monocultures have?
- Pest and disease spread faster
- Makes it harder to encourage local flora and fauna
