the original labor of construction, added to that of maintenance, makes a total far beyond our comprehension and nearly all of it is the product of human effort.
|
Fig. 152.— Looking down a steep, narrow Japanese valley at small, flooded and transplanted rice paddies.
The laying out and shaping of so many fields into these
level basins brings to the three nations an enormous
aggregate annual asset, a large proportion of which western
nations are not yet utilizing. The greatest gain
comes from the unfailing higher yields made possible by
providing an abundance of water through which more
plant food can be utilized, thus providing higher average
yields. The waters used, coming as they do largely
from the uncultivated hills and mountain lands, carrying
both dissolved and suspended matters, make positive
annual additions of dissolved limestone and plant food
elements to the fields which in the aggregate have been very
