That situation is the basis of what Marx calls differential rent I--the investor who produces wheat on the more productive lands reaps an extra-profit or rent, which varies according to the total supply and demand of wheat and the ruling market price for wheat.
That situation is the basis of what Marx calls differential rent I. Marx made his criticism of Ricardo's theory of rent on this point in an early letter to Frederick Engels written on January 7,1851. This rent, of course, varies according to the total supply and demand of wheat and the ruling market price for wheat.