above what was necessary to keep it in its present use (what
we now call economic rent).
Later, two facts were realized that broke the close connection
between the rental price for land and the concept of economic
rent. First, land often had alternative uses, and, from the point
of view of any one use, part of the payment made to land would
necessarily have to be paid to keep it in that use. In other
words, not all of the rental price for land is economic rent.
Second, factors of production other than land also often
earned a surplus over and above what was necessary to keep
them in their present use. This surplus is now called economic
rent, whether the factor is land, labour, or a piece of capital
equipment.
David Ricardo was the first economist to clarify the connection
between factor earnings and economic rent.