Similar to the formulation for wage, MPKM is the marginal product of capital in
manufacturing and MPTA is the marginal product of land in agriculture.
Change in the Real Rental on Capital To understand the effect of an increase in the
price of manufactures on the rental on capital, holding the agriculture price fixed, recall
that due to the change in the relative price of manufactures, the wage rises throughout the
economy. With the higher wage, labor shifts from agriculture into manufacturing, which
Change in the Real Rental on Land Contrary to the case for capital, however, the loss
of labor to manufacturing leads to a fall in the marginal product of agriculture. It follows
that the decline in MPTA means that the real rental on land in terms of food has fallen.