Nearly 500,000,000 people are being maintained, chiefly upon the
products of an area smaller than the improved farm lands of the
United States. Complete a square on the lines drawn from Chicago
southward to the Gulf and westward across Kansas, and there will be
enclosed an area greater than the cultivated fields of China, Korea
and Japan and from which five times our present population are fed.

The rainfall in these countries is not only larger than that even in
our Atlantic and Gulf states, but it falls more exclusively during
the summer season when its efficiency in crop production may be
highest. South China has a rainfall of some 80 inches with little of
it during the winter, while in our southern states the rainfall is
nearer 60 inches with less than one-half of it between June and
September. Along a line drawn from Lake Superior through central
Texas the yearly precipitation is about 30 inches but only 16 inches
of this falls during the months May to September; while in the
Shantung province, China, with an annual rainfall of little more
than 24 inches, 17 of these fall during the months designated and
most of this in July and August. When it is stated that under the
best tillage and with no loss of water through percolation, most of
our agricultural crops require 300 to 600 tons of water for each ton
of dry substance brought to maturity, it can be readily understood
that the right amount of available moisture, coming at the proper
time, must be one of the prime factors of a high maintenance
capacity for any soil, and hence that in the Far East, with their
intensive methods, it is possible to make their soils yield large
returns.

The selection of rice and of the millets as the great staple food