hile the rice and millet eaters of Asia would
continue to increase. Sir William was laughed at then as a
sensationalist. He was, but his sensations were apt to prove true and it
is already evident that he was too near right for comfort. Before we
were half way to the date he set we had two wheatless days a week,
though that was because we persisted in shooting nitrates into the air.
The area producing wheat was by decades:[1]

THE WHEAT FIELDS OF THE WORLD

Acres

1881-90 192,000,000
1890-1900 211,000,000
1900-10 242,000,000
Probable limit 300,000,000

If 300,000,000 acres can be brought under cultivation for wheat and the
average yield raised to twenty bushels to the acre, that will give
enough to feed a billion people if they eat six bushels a year as do the
English. Whether this maximum is correct or not there is evidently some
limit to the area which has suitable soil and climate for growing wheat,
so we are ultimately thrown back upon Crookes's solution of the problem;
that is, we must increase the yield per acre and this can only be done
by the use of fertilizers and especially by the fixation of atmospheric
nitrogen. Crookes estimated the average yield of wheat at 12.7 bushels
to the acre, which is more than it is in the new lands of the United
States, Australia and Russia, but less than in Europe, where the soil is
well fed. What can be done to increase the yield may be seen from these
figures:

GAIN IN THE YIELD OF WHEAT IN BUSHELS PER ACRE

1889-90 1913

Germany 19 35
Belgium 30 35
France 17 20
United Kingdom 28 32
United States 12 15

The greatest gain was made in Germany and we see a reason for it in the
fact that the German importation of Chilean saltpeter was 55,000 tons in
1880 and 747,000 tons in 1913. In potatoes, too, Germany gets twice as
big a crop from the same ground as we do, 223 bushels per acre instead
of our 113 bushels. But the United States uses on the average only 28
pounds of fertilizer per acre, while Europe uses 200.

It is clear that we cannot rely upon Chile, but make nitrates for
ourselves as Germany had to in war time. In the first chapter we
considered the new methods of fixing the free nitrogen from the air. But
the fixation of nitrogen is a new business in this country and our chief
reliance so fa