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Chapter 3 Agricultural Land Use Models
The various elements of the farming system, in spatial
applications, are the locational factors to determine the land use
patterns of farming. Models of agricultural land use location have
been developed.
A. von Thünen's land use rings
Von Thünen's model was based on econometric analysis in
1826.
a. Hypotheses
The model is developed on the basis of two hypotheses:
1.
Agricultural land uses depend on their respective
distances from the market.
The model stresses the distance from market as the most
important controlling factor on agricultural land use.
2.
Intensity of agricultural production increases towards
the market.
This model is an application of the distance decay
mechanism. Again, the distance from market is the most important
controlling factor. As a function of distance, more intensive farming
is located nearer the market. Farther away from the market, the
farming is more extensive. The intensity of production shows a
negative relationship with distance from market.
b. Assumptions
To illustrate the importance of the distance factor,
assumptions have to be set so that the other controlling factors are
made constant.
1. Isolated state
Under von Thünen's idea, the farming pattern applies to a
nation which is isolated from outside. It is a closed system without
external trades and influences.
2. Sole market
Von Thünen's isolated state is centred with the only market,
the central city of the state.
3. Isotropic surface
To make the distance from market uniform, no areal
variations in physical environment is found. All of the relief, soil and
climate are uniform.
4. Commercial nature
All farm products are sold in the central market. They are
not stored up for future sale.
5. Economic humankind
All the farmers are regarded as economic humankind. They
aim at maximizing their profits in their farmwork.
6. Full information
All the farmers acquire full knowledge from information
sources on the demand and the market prices.
7. Unique price
The price of a particular crop is the same in the market at
any one time. This avoids market competition.
8. Equal access
All the farms at a particular distance from the market have
equal access to the market, i.e. all of them have a straight road
leading to the market.
9. Unique transport means
Only one type of transport means is used. It was horse-carts
at the time of von Thünen's.
10. Constant freight rate
The freight rate is constant throughout the isolated state.
The total transport cost is a function of distance from market.
Transport cost  Distance
c. Economic rent
How a piece of farmland can be profitable is based on its
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economic rent. The term is also known as land rent or locational
rent. It is the return that can be obtained from a piece of farmland
over which can be obtained from the land at the margin of
economic cultivation.
As distance from market is the only variable in the model:
E = Y(p-c)-Yfd
where E = economic rent
Y = yield (amount of production)
p = market price per unit of yield
c = fixed cost of production per
unit of yield
f = freight rate
d = distance from market
(Yfd = total transport cost)
Economic rent is also a distance decay function with
distance from market. Closer to the market, the economic rent is
higher. At the margin of economic cultivation, E = 0.
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1. Market-oriented crops
Bulky or perishable crops are market-oriented. Because of
their higher freight rates than non-bulky or non-perishable crops,
their margin of production is closer to the market. On the other
hand, their higher market prices lead them to have a higher
economic rent at places near the market. As a result, they are
cultivated at locations near the market.
2. Intensity of production
With a higher intensity of production, more inputs are
devoted into the cropping process. The production cost is thus
higher than less intensive one. Although there is a higher yield so
that a higher economic rent is obtained, it is in diminishing return.
Besides, the total transport cost also increases. The margin of
economic production is thus closer to the market. As a result, more
intensive production is found nearer the market than the extensive
one.
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d. Land use rings
According to the location of market-oriented crops and
intensity of production, von Thünen developed a structure of 6 land
use rings to show the concentric zonal pattern of agricultural land
use around the central market.
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1. Free cash cropping
This forms the innermost ring. Market gardening and
dairying are practised, using town manure. The products are
perishable. They should be transported to the market in fresh.
2. Forestry
The ring was important at von Thünen's time as firewood
was the major fuel. As wood is bulky, it is sited close to the central
city.
3. Crop alteration system
Arable farming is found. It is very intensive and crop rotation
is adopted. At von Thünen's time, the major crop was rye.
4. Improved system
The system is less intensive. Mixed farming is adopted, with
fields in fallow and pasture. The main crop was also rye.
5. Three-field system
The system is extensive. The farm is divided into three
broad areas for different extensive cropping.
6. Stock farming
This forms the outermost ring. Livestock, chiefly beef cattle
or sheep, is reared on natural pasture.
e. Criticisms and modifications
Von Thünen's model is too simplified and is not applicable to
the real world, even in his time. There are many modified cases
which are more realistic, as in Hong Kong and New South Wales of
Australia.
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1. River navigation
Rivers should not be omitted in the isolated state. They are
important control of farming. Besides, river transport is cheaper
than road transport.
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At von Thünen's time, river transport cost only 10% of that
by horse-cart. River transport is especially favourable for the bulky
wood. The ring of forestry thus extends along the rivers.
2. Alternative markets
There is not only one market in the centre of the isolated
state. Minor markets usually occur in the midst of rich farmlands for
convenient trading. These markets may be periodic. Later, a small
town may appear as a small market town. Another ring structure,
though smaller in areal extent, is resulted around this minor market.
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3. Varied physical environment
The isolated state cannot be isotropic. There are variations
in physical conditions, either regional or local. Different slopes
occur, soils vary in fertility, and both temperature and rainfall are
not unique everywhere. Local variations in cropping pattern thus
occur.
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If a piece of swampland is present, the land use rings may
extend outwards for compensation.
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4. Perception
Farmers are not perfect economic man. Their own
perception and the knowledge are important filters on the choice of
crops and livestock. In most cases, their economic rent is not
optimal.
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5. Tariff
Isolated state never exists. Trading with the outside world
does happen. In modern times, foreign countries may impose tariff
which increases the cost of certain crops. The economic rents of
such crops then decrease.
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6. Tax
If tax is imposed on certain agricultural products, the crops
may reduce in production area as the production cost is higher.
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7. Increased market price
When the price of a particular crop increases, the higher
revenue from this crop may attract the farmers to devote their land
to the cultivation of the crop. Then, the land use zone will expand.
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8. Drop in market price
If the market price of a particular crop drops sharply, its
economic rent reduces so that its cropping may be abandoned.
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9. Drop in freight rate
If the freight rate of a particular crop is reduced, its total
transport cost is lowered. Its cropping area then expands as it is
more profitable.
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B. Sinclair's model
Sinclair model was developed in 1967 as a critique on the
traditional von Thünen's model.
a. Urban encroachment
Sinclair paid special attention to the post-war urban
expansion which was common in the developed world. Due to
urban growth, farmland around the city fringes will gain a much
higher land value. It may finally be encroached for building roads,
houses or industrial estates.
Farmers will then prefer to wait for selling their farmland for
urban development. The value for farming therefore decreases.
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Farming close to the city market thus becomes extensive.
Besides, many farmers prefer to leave their farmland for the urban
life. The rural-urban migration results in loss of farm labour so
that farming intensity also decreases, as in the case of Hong Kong.
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b. Land use zones
The effect of urban growth leads to a reversed pattern in
production intensity as that described by von Thünen. The intensity
of production now shows a positive relationship with the distance
from market. That is to say, farming generally becomes more
intensive in locations farther away from the expanding city which is
the market.
Sinclair developed 5 land use zones:
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1. Urban farming
This forms the innermost zone. Farming here is based on
the demand from the urban city. There are greenhouse cultivation
and poultry farming. These farming systems are under insecurity.
They may be given up immediately when urban encroachment
takes effect.
2. Vacant or grazing
The land is abandoned and awaiting for urban development.
Some land may be rented out for short-term grazing.
3. Field crop and grazing
This is extensive farming. Field crops are grown. Some of
the land may be used for grazing.
4. Dairying and field crops
The farming systems are more intensive. With improved
treatment and transport technology, dairying can now be sited far
away from the city market.
5. Specialized field grains and livestock
Farming in the developed world is now commercial. Farthest
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away from the city market, farming is comparatively most intensive,
such as the farming system in the Corn Belt of the USA. Efficient
transport allows large-scale commercial farming in such remote
areas.