AGRICULTURAL POLICY – COBWEB MODEL
BY: EDE KENNETH .K. & JOHN ANI .E.
Agricultural goods are subject to variations in
production for a variety of natural reasons. Excess rainfall, drought, pests
and disease occur sporadically to cause differences between the planned output
and that actually harvested or produced. Now, the demand for foodstuff is
typically inelastic, so that shortages will force up prices considerably and
gluts will produce very low prices. If the elasticity of demand is – 0.25, for
example, then when production falls by 10%, prices rise by 40%. This inherent
instability has given rise to a history of government intervention in
agricultural markets.
The objectives of such intervention have varied
from time to time but two of the most popular advocated have been to stabilize
either food prices or farmers’ income. Assuming the demand curve is relatively
stable, price and income fluctuations will be caused by supply fluctuations. A
simple way for the government to keep food prices constant would be for them to
establish a “Buffer Stock”. Then in the time of scarcity when the shortage
would have caused prices to rise the government releases sufficient stocks to
keep the market price constant. In years of bumper crops, when the excess
supply would have reduced prices considerably, the government adds to its
stocks, again so as to maintain constant market prices.
Fig. below shows the level of planned output for
each market price. D is the relatively inelastic market demand curve. P1
and Q1 represent the average market price and quantity sold
respectively. When the actual output increases say to Q2 the
government buys (Q2 – Q1) to add to its stocks. When
output falls below average, say to Q3 then the government releases
(Q1 – Q3) to be sold on the market.
This policy stabilizes farm prices completely at P1
and given this would have been the average equilibrium price, the government
can successfully operate this system indefinitely, provided it is prepared to
subsidize the scheme to the extent of
covering the costs to storage, which are not recovered elsewhere.
The effect of such a
price stabilization policy on farmers’ income may be seen as follows: whatever
the level of current output, the farmers either sell it on the market at price
P1, or the government buys it to add to the buffer stocks, again at
a price P1, i.e. the farmers face a perfectly elastic demand curve
at a price P1. Thus, their income which is the total revenue (P x Q)
they earn on the output they sell is directly proportional to the current
output level. In poor years, their income will be low (as output is low), in
good years, their output will be high (as output is high). Note that this
effect on farmers’ income is the opposite of what would happen if the
government had not intervened.
In order to stabilize
farmers’ incomes, the government should stabilize their total revenue. If the farmers
faced a demand curve for their product which was unitary elastic then their
total revenue would be constant as the effect on revenue of quantity changes
would be offset by compensating price changes. As we have said that market
demand curve for agricultural goods is typically inelastic.
If the government
chose to stabilize farmers’ income at their average level, i.e. at TR = P1Q1
in the fig above, then when fluctuation in output occur they must allow the
market price to vary in the opposite direction by the same percentage amount,
by adding or subtracting from their buffer stocks. Thus the actual demand curve
facing producers D’ is unitary elastic and differs from the market demand curve
D by the extent of government purchases or sales (the horizontal difference
between D’ and D).
To maintain farmers’
income constant, when production falls to Q3 we require a price P5
(since P1Q1 = P5Q3 as both points
lie on the same unitary elastic demand curve). At a price P5, the
market demand exceeds the producers’ output by an amount (Q5 – Q3),
which the government must release from its buffer stock.
Stabilizing farmers’
incomes in this way reduce fluctuations in prices which would be observed in
free markets and also may show an operating surplus. The government would add
to its stocks when prices are low, and sell from them when prices are high. If
storage costs are not excessive, this scheme will be profitable.



