Manipulated ecosystem
(Farming)
Inputs from the physical environment
•Solar energy / temperature
•Rainfall / moisture
•Topography / relief
•Soil
•Plant nutrients
Inputs from the human environment
•Labour
•Cultural values
•Transport
•Planting materials
•Technology
•Government influence
•Capital / equipment
Agricultural products Market Cash
Waste products
Agricultural systems
Biotic
AboticAbotic
Biotic
Ecological system• Manipulated ecosystem• For yields (desired products)• Provide the most favourable conditions for the plants and
animals he wishes to produce.
Agro-ecosystem VS natural ecosystem
Natural ecosystem Agro-ecosystem
Inputs Physical inputsThe SUN
Physical + Human inputs
Disposal of outputs Return to the ecosystem For sale
Roles of man Indirectly affect the input Control the inputs and processes
Nutrient cycling/ Flow of energy
Continuous Interrupted with energy subsidy in various formi.e. Chemical fertilizer
Crop/ Livestock selection and species diversity
Higher biodiversity Larger number of species
Lower biodiversity Monoculture/ Polyculture
Stability Stable Unstable
Ecological system – Energy Flow
• Energy efficiency
• Energy Yield Ratio=energy output / energy input
• The higher the energy yield ratio, the more the efficient the ecological system
Energy efficiency
Source of Energy Example Energy Yield Ratio
High Energy system
Solar energy
Vast inputs of fossil fuels
Farms in USA, Western Europe….
0.38:1
Low
Medium Energy system
Energy input from the sun, wind & use of animals
Wet rice cultivation in Asia
4:1
Medium
Low Energy System
Solar energy mostly Shifting cultivation in SE Asia, Pastoral nomads
16:1
High
Ecological system – Nutrient CycleNatural Agricultural system
Nutrients circulate within the ecosystem
Removed entirely by prolonged cropping without compensating fertilizer input
Nutrients are replaced again and again from different parts of ecosystem
Heavily subsidized by input of chemical fertilizers
Unavailable or accumulate to toxic level
Ecological system - StabilityNatural Agricultural system
Solar energy drive energy flow and nutrients cycle
Complex ecological linkages
Large biodiversity
self-maintained and stable
solar energy + human energy inputs Energy flow and nutrients cycle
Fewer crops and animals or even monoculture
maintained by human effort
unstable
Economic system
• Inputs as capital and human effort– Investment (inputs)
• Form of money• Form of labour
• Outputs as financial gain
• Farmers need to make decision about – How much to invest and;– What aspects they are going to invest.
Economic system – decision making
• Key questions– What to produce?– How much to produce?– How to produce?– How much to invest?– What to lease?– How much to lease?– Where and how to buy?– Where and how to sell?
Economic system – decision making
• Result of decision by farmers– land use, cropping, use of biological inputs, total outputs
and farming method and pattern……
Final goal profit satisfaction or maximization?
Economic system – decision making
• Reasons:– Imperfect information – Lack of capital – Social customs may work against improvement– Personal characteristics
• Farmers are satisfiers• Farmers may be conservative and consider a low
degree of risk• Farmers don’t want the extra work and they want to
have more leisure time.
• Decisions result in action which may result in land use patterns, wealth or poverty
• Wealth economic surplus innovation • Poverty stagnation
Economic system – decision making
• Papua New Guinea– Subsistence economy– Farmers– Minimum investment
(human and cultural inputs)
– For tribal or village consumption
– Localize– Response to natural
conditions
• Australia– Commercial economy– Entrepreneurs– Heavy investment (human
and cultural inputs)– For sale (foodstuff,
industry, urban)– Globalize– Response to markets