40 THE SHADOW OF THE WORLD’S FUTURE 
enormously altered, as some persons have somewhat 
speculatively supposed, but it has recently been shown 
that greatly increased yields are at least temporarily 
attainable with cereals by transplanting. The in- 
creased yields are due to the greater root-development 
thus obtained. The use of carbon dioxide has also led 
to higher yields. We see, therefore, that improved 
agricultural technique may yet yield surprising results. 
Whether on a large scale such results are readily 
obtainable or not, and whether it is possible to increase 
yields three- and four-fold permanently or not, it is 
perhaps too early to say. In any case these results, 
while they relieve the outlook for the immediate 
future, do not warrant any disregard for the outlook 
resulting from population-increase. 
It may here be noted that China, which has at any 
rate till recently produced probably the highest yields, 
has for many centuries used human waste. Experts 
have stated that before long this will be a feature of 
all agriculture: world-economics will, it is alleged, 
make it necessary. There is reason to believe that, in 
human affairs, waste of material and of effort will 
continually diminish. 
One is reminded also, in this connection, that the 
extent of the possible use of fertilisers is a factor 
of great moment. In South Australia, for example, 
wheat-growing was unprofitable until superphosphates 
were used; and as soon as they were used the economic 
position was completely altered for the better. Before 
passing on, however, to consider the light which the 
use of manures throws on the world’s possibilities of 
population, some consideration may be given to the 
magnitude of the production of artificial fertilisers. 
Statistics are collected regarding these by the Inter- 
national Institute of Agriculture at Rome. For 1920 
the production in millions of metric tons—2204-6 Ibs. 
—was as follows sem