Suggested Answers
I. What is agriculture?
Agriculture refers to the purposeful raising of crops and livestock by man to produce useful commodities e.g.
foodstuff and fibres.
II. What is the importance of agriculture?
1.
2.
3.
4.
a source of food and raw materials
a major employment
a major land use
important trade items
IV. Types of farming
1.
Arable, pastoral and mixed
Type
Arable farming
Pastoral farming
Mixed farming
2.
Subsistence and commercial
Type
Subsistence farming
Commercial farming
3.
Destination of Outputs
outputs are for own consumption
outputs are for sale in market
Shifting and sedentary
Type
Shifting farming
Sedentary farming
4.
Outputs
crops only (cash crops or cereal crops)
livestock
crops and livestock
Farm location
temporary, relocation is frequent
fixed and unchanged
Extensive and intensive
Type
Labour extensive farming
Capital extensive farming
Labour intensive farming
Capital intensive farming
Input : land ratio
low man-land ratio
low capital-land ratio
high man-land ratio
high capital-land ratio
A. Farming as an ecological system / agroecosystem
1. What is an ecosystem?
An ecosystem is a community composed of living organisms and the non-living environment in
which they live. An ecosystem is a natural unit in which the life-cycles of plants, animals and
other organisms are linked to each other and to the non-living constituents of the environment
to form a natural system. Ask students to decide which one is better.
2.
Describe the structure of an ecosystem.
Biotic components
Abiotic components
producer--green plants,
nutrient pools:
autotrophs,
atmospheric components
fix sunlight, self-nourishing
consumers-herbivores
carnivores
omnivores
decomposers-bacteria
fungi
invertebrates
3.
lithospheric components
hydrospheric components
Describe the functional characteristics of an ecosystem.
Energy Flow
1. Energy flow is the transfer of energy through various living
organisms along the food chain.
2. Plants absorb solar energy and produce organic food by
photosynthesis.
3. Part of the energy in food is used by plants themselves during
respiration.
4. Another part of the energy is stored in the plants and then
passed on to the primary consumers when they eat the plants.
5. When the primary consumer is eaten, energy is passed on to the
secondary consumers in the same way.
6. At each trophic level, a large part of energy is used up in the
organisms’ respiration and metabolic activities.
7. Respiration produces heat energy which is lost. This is called
heat loss.
8. That is to say, as each higher trophic level is reached, there is an
accumulated loss in energy.
9. 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.
10. Such continuous loss of energy can be shown by a production
pyramid.
Nutrient cycling a. Inorganic nutrients are taken up by plants to make organic matter
during photosynthesis.
b. The nutrients are then passed form one living organism to another
along the food chain.
c. When the living organisms die, their dead bodies are decomposed
by bacteria and fungi.
d. through decomposition, the organic matter is converted back into
simple inorganic substances such as water and carbon dioxide
e. All the nutrients are then returned to the atmosphere,
lithosphere or hydrosphere.
f. When these nutrients are taken up by plants again, new nutrient
cycles start.
4.
Taking rice farming in South China as an example of an agroecosystem, describe its
structural and functional characteristics.
Structural Characteristics
Biotic Components
Abiotic Components
Producers: rice/padi
Atmospheric : sub-tropical monsoon climate
weeds (grass,
20℃ for 8 months
unwanted species)
1200-3000mm rainfall
some vegetables in
Lithospheric : river valleys, deltas, flood plain
winter
terraces on hilly land
Consumers: animals (pigs/poultry)
clayed/alluvial soil
pests
Human environment : subsidized energy in terms of
human beings
irrigation, machines, fertilizers or manure
Decomposers: bacteria
fungi
invertebrates
Functional Characteristics
Energy flow: high temperatures all the year round encourages photosynthesis continuously;
primary productivity is high, long-growing season, double or even triple cropping
possible; energy subsidy used; this encourages the growth of padi and other weeds;
including labour saving tools (machines), crop protecting means (herbicides and
pesticides) and land protecting means (irrigation and fertilizers)
Nutrient
alluvial soils, rich in nutrients (humus), uptake by padi during photosynthesis,
cycling:
harvest removes nutrients from the system; natural cycling of nutrient is not
complete; thus nutrients have to be replenished by applying manure or chemical
fertilizers
5.
Taking shifting cultivation in Southeast Asia as an example of an agroecosystem, describe its structural
and functional characteristics.
Structural Characteristics
Biotic Components
Abiotic Components
Producers: crops include rice, pea, Atmospheric : tropical rainfall forest climate
maize, vegetables, groundnuts,
about 28C all year round
sweet potatoes, taro, yams,
2000-22000mm annual rainfall
millets, banana, cotton,
Lithospheric : hillslopes, swampy land
tobacco, betal etc.
poor tropical soils
heavily leached with little humus
Consumers: human population in Human environment : simple tools to enable slash,
the tribes,
burning trees supplies nutrients to soils
reared livestock mainly pigs and
little subsidized energy in terms of
poultry
machines or manure
pests including wild animals, birds,
rats etc.
Functional
Characteristics
Energy flow: high temperatures all the year round encourages photosynthesis continuously;
primary productivity is high, continuous growing all the year round; frequent
harvest as food supply to tribal population; some crops such as sweet
potatoes, taro are used as fodder; pig herds supply protein to people, little
energy subsidy used, mainly labour input; weeds and pests flourish; swiddens
finally resume to secondary forest
Nutrient
tropical soils are heavily leached; lacking of nutrients for crop growth; slash
cycling:
and burn release nutrients stored in biomass to soils, this facilitates cropping
for 2-3 years, nutrients loss due to harvest and leaching without much
replenishment from nutrient pools; decrease productivity due to lack of soil
fertility; relocate farming to other places; swiddens left fallow for 20-30
years and finally resume to forest biome
Comparison of agroecosystems and natural ecosystem
Items for comparison
Unmanaged ecosystem
Agroecosystem
Role of man
man is an insignificant element exerting man becomes the ecological dominant,
limited influence upon it, e.g. the hunting human impact on ecosystem components
& gathering
is great
Inputs
- natural inputs: mainly sunlight ,
- others: soil, rainfall, relief,
plant nutrients.
- natural as well as human inputs.
- especially auxiliary energy
(subsidized energy)
- no human input.
Energy flow
-fix maximum sunlight for photosynthesis - by employing auxiliary power to
- longer food chain / more trophic levels
farm work
- allow more energy to be converted
directly to food
- shorter food chain
Nutrient cycling
-
natural cycling of nutrients
operated in a relatively closed system
nutrient cycling modified, operated in
a relatively open system
- no ‘waste’ produced
(harvest output)
- man-made outputs: waste & pollutants
Biomass
-biomass amount reach maximum
under the prevailing environment
- Seasonal variation of biomass not so
distinct since there are many species, each
follows its own seasonal growth cycle
- if original ecosystem is forest, biomass
of standing crop even at harvest time is
smaller
- if original ecosystem is grassland (or
desert), biomass of the farm may be
greater than original at harvest time
- Seasonal variation of biomass is
distinctive, great contrast between
sowing & harvest time.
Diversity of
organisms
-greater diversity
-most crops are genetically uniform,
-species are selected by natural process of equally cold, drought & disease resistant,
evolution
liable to hazards (same degree of
- there are many natural habitats (niches), tolerance)
so more species can be developed
- artificial selection of species by
- cross-bred & hybridization
- habitats for crops are man-made;
unwanted species are called pest or weed
Stability
- structure more complicated, usually more - structure more simple
stable
- high shoot-root ratio
- due to greater diversity of organisms - equal degree of tolerance
- ∴more stable
- soil exposed at harvest time
- ill-managed and suffered from pollutants
∴less stable
B.
1.
2.
Farming as an economic system
What is the main concern of a farmer if he operates his farm as an economic system?
Whether the inputs of capital and labour can result in financial gain.
What decisions have farmers to make in a farming economic system?
 Selection of crops and/or livestock : What to produce?
 Selection of production methods : commercial/subsistence & intensive/extensive
 How much to produce?
 How 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?
3.
What influence farmers’ decision-making processes ?
The prime influence is a farmer’s knowledge of the physical conditions/factors, economic factors and
social & political factors. What the farmer ultimately decide to do depends on his/her value, belief and
attitude.
4.
Using examples, explain why agricultural patterns vary in different areas.
The pattern of agricultural land use is the result of decision-making processes by individual farmers, groups of
farmers or the state. In agriculture, the basic decision includes the allocation of human and capital resources
and the choice of crops and/or livestock. The decision in turn is collectively controlled by a complex set of
factors mentioned in Question 3 above. Hence the resulting agricultural patterns may vary.
For instance, in Hong Kong, farmers perceived differently in view of the most economical way of using their
farmland. Some may abandon their land for speculation and resumption. Some practice marketing
gardening by growing vegetables and flowers. Even being market gardeners, farmers may grow different
kinds of vegetables or flowers according to their skills and experience. Hence the agricultural patterns in
Hong Kong still vary a little bit in different areas.
5.
Describe how vegetable farming/ market gardening in Hong Kong works as an economic system.
Economic decisions
What to produce?
(Output combination)
Marketing gardening in Hong Kong
Vegetables : lettuce, hairy melon, Chinese mushroom, Chinese white
cabbage, tomato etc.
Flowers : gladiolus, chrysanthemum, orchid etc.
Fruits : banana, mandarin, guava etc.
continuous cropping throughout the year, 6-8 crops of vegetable
How to produce?
(Input combination & irrigation is necessary in the dry winter
the size of farm is small
farming processes)
farming is very labour-intensive
terracing is practiced on hill slopes
application of fertilizers and pesticides is necessary
most farm are operated on family basis
small hand machines are used
Where and how to sell? produce meets the demand of local market only
vegetables harvested are sent to collection stations of the cooperative
bulk products of the cooperative are then sent to the VMO (Vegetable
Marketing Organization) at Cheung Sha Wan
VMO sells the vegetables to retailers
some farmers by-pass the VMO and sell their vegetables directly to
customers in market
part of the income received is re-invested to the farm for next harvest
6.
Describe how sheep-wheat farming in Australia works as an economic system.
Economic decisions
Sheep-wheat farming in Australia
crops : wheat, barley, fodder crops such as hay
What to produce?
(Output combination) livestock : sheep for their wool, meat or milk
farming is labour-extensive
How to produce?
(Input combination & large farm size with high level of mechanization
large capital inputs for machinery, farm equipment
farming processes)
advanced technology is used to control weeds and pests (extensive use of
pesticides & herbicides)
medicines and vaccination are given to improve the quality of the
livestock
scientific farming methods are used to improved productivity, e.g. crop
rotation, seed selection, breed selection, dry farming techniques & research
heavy use of chemical fertilizers to ensure the wheat production and the
growth of pastures
good irrigation system using water from river and artesian wells provides
enough water for sheep and wheat
Where and how to sell? produce is mainly for overseas market
using refrigeration transport technology, farm produce is sent to nearby
ports by rail
large bulk carriers sent the produce to distant overseas market for sale
profit is guaranteed by floor prices set by government
7.
Describe how farmers select their crops and/or livestock and production methods in rice
cultivation in South China.
Decision
Ecological consideration
Economic consideration
Selection of crops
and/or livestock
Rice is a tropical crop. South China
has the physical conditions favourable
for rice cultivation.
Rice requires high temperature at
about 20oC during the growing season.
Growing season should be long, not
less than 4 months. Abundant
rainfall , about 1800 mm or over, is
needed. A short, drier period for
ripening is required. Subsoil should
be impermeable for a flooding ground.
Level relief is desirable.
Rice is the chief foodstuff of the
people in South China. The local
demand is large.
Rice cultivation has been carried in
China for thousands of years. Rice is
nutritionally very high. Its supply
feeds the large population in South
China.
Rice cultivation has a long history.
Farmers have acquired the necessary
techniques and experience for its
cultivation.
In 1982, the production responsibility
system was introduced. Farmers can
sell their product in open market.
Farmers have greater incentive to
improve their production.
South China is densely populated.
The dense population provides a large
and abundant cheap labour. So
Selection of
production
methods
South China has a sub-tropical
monsoon climate with long and hot
summer. Winter is short and mild.
Therefore double cropping is
common.
Winter is dry. Irrigation is practised.
Most parts of South China are hilly.
So terracing farming is common on
hillslopes.
Limited level land for rice cultivation
is available only in river valleys, deltas
and flood plain. As a result, the size of
farm is small. Cultivation is very
intensive.
Fertile alluvial soils are found in
valleys and deltas. In these areas,
continuous cultivation is practised.
In other areas, soils developed in
granitic hills are thin, acidic and
infertile. Fertilizers and manure are
widely used.
farming is labour-intensive. Yield
per hectare is high. Yield per capita
is low.
Modern farming technology is
introduced. Small machines are used.
Irrigation projects are carried out.
Better varieties of rice are introduced
which can produce higher yields.
Traditional farming methods are
still widely adopted since modern
technology is expensive.
8. Describe how farmers select their crops and/or livestock and production methods in shifting cultivation
in Southeast Asia.
Decision
Ecological consideration
Economic consideration
Selection of A large variety of crops are grown.
The great varieties of crops is nutritionally
crops and/or Examples are rice, maize, yams, taro, sugar necessary. A good diet should include a
livestock cane, sweet potatoes, beans, squash etc.
variety of vegetable food and animal
The tropical rainforest climate provide the protein, Rice and maize is related to the
physical conditions for their growth.
dietary habit of the tribal people. Starchy
root crops such as taro and yams are
It is ecologically sensible to have more
variety of crops within a swidden. Beans are nutritionally very high.
ecologically desirable, because they help to Non-food crops such as Tobacco and betal
fix nitrogen in the soil.
are socially desirable. The tribal people
have the habit of chewing tobacco with
 Pigs and poultry are reared to supply
betal. Cotton is used for spinning and
additional protein. Farming is mixed in
weaving. Derris is used in fishing,
nature.
Vetiver is used for making perfume bag for
females.
Sweet potatoes and yams are used for
feeding pigs. Pigs serves not only a source
of meat in diet. It is also a means of
achieving status through ownership and
through display during occasional feasts.
Selection of Slash-and-burn method is used. It is a
Farmers clear a site just large enough for
production most practical way of clearing a forest area the survival of the tribe. There is no
methods for cultivation. The ash after burning
incentive to increase production. All
served as a natural fertilizer. Nutrients
crops are produced by neighbouring
stored in the forest biomass is released for population. There is little purpose in
plant growth.
growing large surplus for trade.
Areas for slashing is selected carefully
Simple farming technology is used. Only
through religious ceremony, Burning is
steel axes are used for cutting. Subsidized
under controlled. Stumps of large trees are energy is little. There is no Irrigation or
left behind for soil protection. Trees
application of fertilizers and pesticides.
providing fruits or medicines are not cut.
Simple farming technology is used.
Inter-cropping is common. Different
There is no Irrigation or application of
crops are grown together. This help to
fertilizers and pesticides.
keep soil fertility and lessen the chance of Energy yield ratio is high. It may reach
pest invasion.
16:1.
Farmers move to another site if soil
Frequent harvest is common. Farmers
fertility declines after 2-3 years.
collect just enough crops for their daily use.
The abandoned swidden are left for
Excess harvest is not desirable because it is
succession. If it is undisturbed for 20-30 difficult to store the perishable crops under
years, it may turn back to secondary forest.. the hot wet climatic conditions
9.
Describe how farmers select their crops and/or livestock and production methods in vegetable farming /
market gardening in Hong Kong.
Decision
Ecological consideration
Selection of Various types of vegetables are suitable to
crops
grow in HK.
and/or
livestock Field crops mixed with vegetables are
grown in land with lower soil fertility.
Selection of Farming is highly intensive. Farm size is
production small, ranging from 0.5 to 2.5 hectares.
methods Relief in HK is hilly. Land with high
farming potential is limited in HK.
Farming is heavily dependent on
subsidized energy.
Soils in HK are acidic and lack of nutrients
for vegetable growth. So heavy application
of lime and fertilizers is necessary.
Heavy dose of pesticides and herbicides is
applied. Pest and weed infection are serious
due to the mono-cultural nature of farming
and the hot wet climatic conditions in HK.
Economic consideration
There is a high demand for fresh vegetables
in local urban areas.
Locally supplied vegetables usually have
high market prices.
There is a high percentage of abandoned
farmland. Farmers try to obtain more profit
by speculation and waiting for government
resumption once their land is used for urban
development.
Farmland in HK is not allowed to
converted to other uses without prior
approval from the government. So it is a
good economic choice to use the land for
vegetables.
Free advice and research on vegetable
growing are offered by the Agricultural &
Fisheries Department and Kadoorie
Agricultural Aid Association.
Multiple-cropping, 6-8 crops a years, is
carried out ; can bring more profit.
Farming is labour-intensive. Rural-urban
migration has caused rural depopulation in
the NT. There is a shortage of farm labour.
Small farm machines are used to substitute
laobur.
Vegetable is highly perishable. Frequent
harvest is necessary. It is supported in HK
by good road network system.
Co-operatives for marketing of vegetable
are common. Farmers send vegetables
to co-operative stations. VMO collect
Irrigation by sprinklers is used because of
high evaporation in summer and dry
monsoon climate in winter.
vegetables from each station by offering
farmers the whole-sale prices. This ensures
the sale of vegetables in market.
10. Describe how farmers select their crops and/or livestock and production methods in sheep-wheat farming
in Australia.
Decision
Ecological consideration
Economic consideration
Mixed farming of sheep and wheat is
practiced.
Physical / ecological conditions are
suitable for the enterprises.
For instance, Well-drained loam soils in
Murray-Darling Basins avoid foot rot
diseases and are fertile enough for pasture
and wheat growth.
The two activities are supplementary.
Wheat provides stubble grazing for sheep.
Sheep waste provides manure for wheat
lands.
Mixed farming helps keep soil fertility and
prevent soil erosion. Crop rotation and
dry farming methods are carried out.
Mixed farming is less risky and ensures a
more stable income.
More income is gained because sources of
income are spread and diversified.
The two activities are complementary.
Labour and farm equipment can be fully
utilized because major work periods occur at
different time.
Mixed farming enables a more efficient use
of farmland. level and fertile lands can be
used for wheat cultivation. Areas with
steeper slope and poorer soils can be used for
sheep rearing.
So the cost of production of mixed farming
is lower.
Selection of Farming is extensive. Farm size is large.
production Each farm usually reaches 400 ha or above.
methods To overcome the problem of soil
exhaustion due to mono-cultural nature of
farming, heavy application of chemical
fertilizers is carried out.
Other land protection methods are used,
like crop rotation & dry farming.
To control weeds and pests, heavy dose of
pesticides and herbicides is applied.
Medicine and vaccination are also given to
improve livestock quality.
Most parts of Murray-Darling Basin is in
the rain shadow of Eastern Highland.
Rainfall is not reliable. Good irrigation
system have to be built. Water is got
from nearby rivers and artesian wells.
Species with good yield are selected.
Biotechnology and research on gene
engineering are carried out.
Population is sparse. Labour supply is
inadequate. Labour costs are high. So
labour-saving farming methods are
necessary.
Farms are highly mechanized, e.g.
harvesting and baling machines, aircraft to
spray crops with pesticides and herbicides.
Large amount of capital are required for
machinery and farm equipment.
 Yield per area is low, but yield per farmer is
high.
Farming is export-oriented. There is good
transport link between the wheat-sheep belt
and the major ports, urban and industrial
centres.
Refrigeration transport technology permits
expert of mutton to distant market.
 Guarantee floor price is offered by the
Australian government. Subsidies and loan
are also provided to farmers.
Selection of
crops
and/or
livestock