he land
on which the sheep were fed becomes unnecessary, and the same quantity
of raw produce is raised by the employment of a less quantity of land.
If I discover a manure which will enable me to make a piece of land
produce 20 per cent. more corn, I may withdraw at least a portion of my
capital from the most unproductive part of my farm. But, as I have
before observed, it is not necessary that land should be thrown out of
cultivation, in order to reduce rent: to produce this effect, it is
sufficient that successive portions of capital are employed on the same
land with different results, and that the portion which gives the least
result should be withdrawn. If, by the introduction of the turnip
husbandry, or by the use of a more invigorating manure, I can obtain the
same produce with less capital, and without disturbing the difference
between the productive powers of the successive portions of capital, I
shall lower rent; for a different and more productive portion will be
that which will form the standard from which every other will be
reckoned. If, for example, the successive portions of capital yielded
100, 90, 80, 70; whilst I employed these four portions, my rent would be
60, or the difference between

70 and 100 = 30 } { 100
70 and 90 = 20 } { 90
70 and 80 = 10 } whilst the produce { 80
-- } would be 340 { 70
60 } { ---
{ 340

and while I employed these portions, the rent would remain the same,
although the produce of each should have an equal augmentation. If,
instead of 100, 90, 80, 70, the produce should be increased to 125, 115,
105, 95, the rent would still be 60, or the difference between

95 and 125 = 30 } { 125
95 and 115 = 20 } whilst the produce { 115
95 and 105 = 10 } would be increased { 105
-- } to 440 { 95
60 } { ---
{ 440

But with such an increase of produce, without an increase of demand,
there could be no motive for employing so much capital on the land; one
portion would be withdrawn, and consequently the last portion of capital
would yield 105 instead of 95, and rent would fall to 30, or the
difference between

105 and 125 = 20 } whilst the produce would be still { 125
105 and 11