Agricultural landscapes

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Agricultural landscapes
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What is agriculture?

• Agriculture refers to the purposeful raising of
  crops and livestock by man to produce useful
  commodities e.g. foodstuff and fibres.

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PROCESSES
PHYSICAL INPUTS
OUTPUTS
CULTURAL INPUTS
MARKET
CASH
MANURE SEED
FARM HOUSEHOLD
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Type of farming

• Arable farming
• Pastoral farming
• Mixed farming

• Crop only(cash /cereal)
• livestock
• crop livestock

• Subsistence farming
• Commercial farming

outputs are for own consumption outputs are for
sale in market
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• Labour extensive farming
• Capital extensive farming
• Labour intensive farming
• Capital intensive farming

• Low man-land ratio
• low capital-land ratio
• high man-land ratio
• high capital-land ratio

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Agroecosystem
An agricultural ecosystem
Farm as an ecological system

• An ecosystem is a functioning and interacting
  system of living organisms and its effective
  environment(including biotic and abiotic)
• Human manipulated ecosystem

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Producers
Nutrient cycle
Energy flow
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Energy Flow

• Energy flow is the transfer of energy through
  various living organisms along the food chain.
• Plants absorb solar energy and produce organic
  food by photosynthesis.
• Part of the energy in food is used by plants
  themselves during respiration.
• Another part of the energy is stored in the
  plants and then passed on to the primary
  consumers when they eat the plants.
• When the primary consumer is eaten, energy is
  passed on to the secondary consumers in the same
  way.

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• At each trophic level, a large part of energy is
  used up in the organisms respiration and
  metabolic activities.
• Respiration produces heat energy which is lost.
  This is called heat loss.
• That is to say, as each higher trophic level is
  reached, there is an accumulated loss in energy.
• Hence there is usually a large number of first
  order consumers, fewer secondary order consumers
  and still fewer third order consumers further
  along the food chain. Such continuous loss of
  energy can be shown by a production pyramid.

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Nutrient Cycling

• Inorganic nutrients are taken up by plants to
  make organic matter during photosynthesis.
• The nutrients are then passed form one living
  organism to another along the food chain.
• When the living organisms die, their dead bodies
  are decomposed by bacteria and fungi.
• through decomposition, the organic matter is
  converted back into simple inorganic substances
  such as water and carbon dioxide
• All the nutrients are then returned to the
  atmosphere, lithosphere or hydrosphere.
• When these nutrients are taken up by plants
  again, new nutrient cycles start.

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A Rice farm in South China as an agroecosystem
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Producers
Nutrient cycle
Energy flow
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Energy flow

• Active photosynthesis
• high primary productivity(double/triple cropping)
  
• energy subsidies are used(fertilizers,
  irrigation, transplanting, machinery)
• man as the major consumer
• herbicides and pesticides are used to minimize
  weeds and pest(competitors)

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Nutrient cycling

• Alluvial soil is rich in nutrients(humus)
• rapid uptaking / large amount
• harvest removes nutrients from system(especially
  for commercial farm)
• natural nutrient cycling is incomplete
• manure/ chemical fertilizers is needed

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Energy efficiency
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Erlt1
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Farming System

• Shifting cultivation
• Subsistence paddy farming
• Commercial wheat farming
• Dairy farming in Australia

• Pre-industrial crops
• Semi-industrial crops
• Full-industrial crops
• Full-industrial livestock

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Difference in Energy Efficiency

• Shifting cultivation has a higher energy
  efficiency than plantation.
• Because of high rainfall and temperature
  (physical inputs) and sudden release of nutrient
  by the burning of rain forest
• Plantations use large amount of energy subsidies
  (machinery and chemicals).

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Difference in Energy Efficiency

• There will be energy and nutrient loss when they
  apply farming chemicals.
• Due to the carrying capacity of land, there will
  be the effect of diminishing return in the
  application of farming chemicals.

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Difference between crops and livestock in Energy
Efficiency

• Both commercial crops and livestock farming
  involve large amount energy subsidies
• However, the food chain of livestock is longer
  (one higher trophic level)
• The longer is the energy flow, then the greater
  energy loss will be

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Difference between crops and livestock in Energy
Efficiency

• Only one tenth can be passed to a higher trophic
  leve
• There is high loss of energy in conversion from
  plant carbohydrate to animal protein

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Farm as an Economic System
Farmer as a decision-maker
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Questions for a farmer

• What to produce?
• How to produce? /Which production method?
• How much to produce?
• How much to invest?
• How much to save and borrow?

• What to hire or lease?
• Where and how to buy?
• Where and how to sell?

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Social political factors
Physical factors
Economic factors
value, belief, atitude
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Market gardening in Hong Kong works as an
economic system
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Decision of farming method
-Mixed farming in Australia
Selection of crops and/or livestock
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