538 TRANSACTIONS OF SECTION E. 
658 million bushels, or about half the estimated increase required by 1931, and 
that attained chiefly by ‘increased acreage: 
But signs are not wanting that increase in this way will not go on indefinitely. 
We note (also from Dr. Unstead’s paper) that in the two later periods the per- 
centage of total wheat produced which was exported from the United States 
fell from 32 to 19, the yield per acre showing an increase meanwhile to 
14 bushels. In the Russian Empire the percentage fell from 26 to 23, and only 
in the youngest of the new countries—Canada, Australia, the Argentine—do we 
find large proportional increases. Again, it is significant that in the United 
Kingdom, which is, and always has been, the most sensitive of all wheat- 
producing countries to variations in the floating supply, the rate of falling-off 
of home production shows marked if irregular diminution. 
Looking at it in another way, we find (still from Dr. Unstead’s figures) that 
the total amount sent out by the great exporting countries averaged, in 1881-90 
295 million bushels, 1891-1900 402 millions, 1901-10 532 millions. These 
quantities represent respectively 13-0, 15-6, and 1671 per cent. of the total pro- 
duction, and it would appear that the percentage available for export from these 
regions is, for the time at least, approaching its limit; i.e. that only about one- 
sixth of the wheat produced is available from surpluses in the regions of pro- 
duction for making good deficiencies elsewhere. 
There is, on the other hand, abundant evidence that improved agriculture 
is beginning to raise the yield per acre over a large part of the producing area. 
Between the periods 1881-90 and 1901-10 the average in the United States rose 
from 12 to 14 bushels; in Russia from 8 to 10; in Australia from 8 to 10. It 
is likely that, in these last two cases at least, a part of the increase is due 
merely to more active occupation of fresh lands as well as to use of more suitable 
varieties of seed, and the effect of improvements in methods of cultivation alone 
is more apparent in the older countries. During the same period the average 
yield increased in the United Kingdom from 28 to 32 bushels, in France from 
17 to 20, Holland 27 to 33, Belgium 30 to 35, and it is most marked in the 
German Empire, for which the figures are 19 and 29. 
In another important paper’ Dr. Unstead has shown that the production 
of wheat in North America may still, in all likelihood, be very largely in- 
creased by merely increasing the area under cultivation, and the reasoning by 
which he justifies this conclusion certainly holds good over large districts 
elsewhere. It is of course impossible, in the present crude state of our know- 
ledge of our own planet, to form any accurate estimate of the area which may, by 
the use of suitable seeds or otherwise, become available for extensive cultiva- 
tion. But I think it is clear that the available proportion of the total supply 
from ‘extensive’ sources has reached, or almost reached, its maximum, and 
that we must depend more and more upon intensive farming, with its greater 
demands for labour. 
The average total area under wheat is estimated by Dr. Unstead as 192 
million acres for 1881-90, 211 million acres for 1891-1900, and 242 million acres 
for 1901-10. Making the guess, for we can make nothing better, that this area 
may be increased to 300 million acres, and that under ordinary agriculture 
the average yield may eventually be increased to 20 bushels over the whole, 
we get an average harvest of 6,000 million bushels of wheat. The average 
wheat-eater consumes, according to Sir William Crookes’ figures, about four and 
a-half bushels per annum; but the amount tends to increase. It is as much 
(according to Dr. Unstead) as six bushels in the United Kingdom and eight 
bushels in France. Let us take the British figure, and it appears that on a 
liberal estimate the earth may in the end be able to feed permanently 1,000 
million wheat-eaters. If prophecies based on population statistics are trust- 
worthy the crisis will be upon us before the end of this century. After that we 
must either depend upon some substitute to reduce the consumption per head of 
the staple foodstuff, or we must take to intensive farming of the most strenuous 
sort, absorbing enormous quantities of labour and introducing, sooner or later, 
serious difficulties connected with plant-food. We leave the possibility of 
diminishing the rate of increase in the number of bread-eaters out of account 
for the moment. 
* Geographical Journal, April and May 1912. 
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