On Rent

Ricardo's rent theory begins with a simple fact: land is not all equally fertile or equally well placed. Rent is the payment for using the superior powers of better land after society has been forced to cultivate worse land too.

Term	Meaning
Rent	The return paid for the original and indestructible powers of the soil
Fertility	How much corn a given amount of labour and capital can produce on land
Situation	Location advantage, such as being closer to market or transport
Marginal land	The worst land currently needed to satisfy demand; it pays no rent in Ricardo's model
Differential rent	The surplus earned by better land over the marginal land
Extensive margin	The movement from better land to worse land as population and demand grow

Rent appears when cultivation must move beyond the best land. If one field can produce 100 quarters of corn with the same labour that another field needs to produce 70, the better field has a surplus once the worse field is necessary.

The key is the last land brought into use. It must cover wages and profits, or no farmer would cultivate it. Because it just covers those costs, it has no surplus left for rent. Better land does have a surplus, and that surplus becomes rent.

Ricardo's famous reversal is that corn is not dear because rent is paid. Rent is paid because corn is dear enough to make poorer land worth cultivating. The price has to be high enough to cover production on the marginal land; once that happens, superior land yields a difference.

growing demand
      ->
worse land needed
      ->
corn price must cover worse land
      ->
better land has surplus
      ->
rent appears

This matters because it changes whom we blame for high food prices. Landlords receive rent, but the immediate regulator is the labour and capital needed on the worst land in use.

Suppose three grades of land use the same labour and capital. Grade A yields 100 quarters, Grade B yields 80, and Grade C yields 60.

Demand requires	Marginal land	Rent on A	Rent on B	Rent on C
Only A	A	0	not used	not used
A and B	B	20	0	not used
A, B, and C	C	40	20	0

Rent rises as worse land enters cultivation. The landlord of A did not make A more productive; the social margin moved downward, and A's advantage became measurable as rent.

Read Ricardo's rent model as a stack of land grades:

        LAND A: 100 quarters   rent = A - marginal yield
        LAND B:  80 quarters   rent = B - marginal yield
        LAND C:  60 quarters   rent = 0 when C is marginal
        -----------------------------------------------
        price of corn is regulated at the margin

The diagram is deliberately vertical. Ricardo wants the reader to see society descending to less productive land as demand expands. Rent is the height of the superior land above the current bottom step.

Ricardo includes location. A farm close to market can be like a fertile farm because it saves carriage cost. Two fields may grow the same corn, but the nearer field may still earn rent if the farther field must be cultivated and its transport cost helps regulate price.

This is why "original and indestructible powers of the soil" should be read broadly. Fertility is the clearest case, but advantageous situation creates the same differential logic.

Rent is the hinge between value and profits. Chapter I said labour cost regulates reproducible goods. Chapter II shows that corn's labour cost can rise when cultivation reaches inferior land. Chapter VI will use that fact to explain why profits fall as food becomes harder to produce.

Once rent is understood, later arguments about corn laws and taxes are less mysterious. A policy that changes which land is profitable to cultivate changes rents, wages, and profits through the margin.

Ricardo's rent theory is differential. Rent is the surplus of better land over the worst land needed to meet demand.

• Rent arises only after land of unequal fertility or situation is brought into comparison.
• Marginal land pays no rent because it just covers ordinary wages and profits.
• Better land earns rent equal to its surplus over marginal land.
• Corn is not dear because rent is paid; rent is paid because corn is dear enough to require worse land.
• The rent model prepares Ricardo's later account of wages, profits, trade, and taxation.

A reader is ready to continue when they can identify the marginal land and compute rent as a difference.

• [ ] Can you define marginal land in one sentence?
• [ ] Can you explain why the worst land in use pays no rent?
• [ ] Can you calculate rent when A yields 100 and C yields 60?
• [ ] Can you use the lab to make rent rise by adding demand?
• [ ] Can you explain why rent is an effect of price, not the cause of price?