unfertilized land was only 756 bushels during the same sixty years.
It is a good fact that the increase alone from the nitrogen applied
is more than twice the total yield of the unfertilized land during
the last thirty years, and he does well who holds fast this fact.

It is also a good fact that as an average of sixty years the yield
of barley was increased by 21.6 bushels an acre by nitrogen; that
nitrogen increased the yield of hay on permanent meadow land at
Rothamsted by 1-1/2 tons an acre as a fifty-year average; and that
nitrogen increased the average yield of potatoes by 88 bushels as an
average of twenty-six years; while the average of the unfertilized
land was only 51 bushels an acre, these increases in barley, bay,
and potatoes being obtained over and above the yields where minerals
alone were used.

Where Is Nitrogen?

If nitrogen has such enormous power to increase the yield of our
great staple farm crops then we may well inquire, Where is nitrogen,
and how can it be secured economically and utilized profitably in
practical agriculture?

The weight of the atmosphere is 15 pounds to the square inch. This
means that a column of air 1 inch square taken to the full height of
the terrestrial atmosphere weighs 15 pounds. More than three fourths
of the air is nitrogen. Since there are 43,560 square feet in one
acre, it follows that the nitrogen in the air above each acre of the
earth's surface amounts to 70,000,000 pounds, or nearly 500,000
times the 150 pounds of nitrogen required for a hundred-bushel crop
of corn. The leaves of the corn plant are blown about by the wind