of other cultivated lands are held in areas less than one-fourth of an acre, and each of these may be further subdivided.  The next two illustrations, Figs. 151 and 152, give a good idea both of the small size of the rice fields and of the terracing which has been done to secure the water level basins.  The house standing near the center of Fig. 151 is a good scale for judging both the size of the paddies and the slope of the valley.  The distance between the rows of rice is scarcely one foot, hence counting these in the foreground may serve as another measure.  There are more than twenty little fields shown in this engraving in front of the house and reaching but half way to it, and the house was less than five hundred feet from the camera.

There are more than eleven thousand square miles of fields thus graded in the three main islands of Japan, each provided with rims, with water supply and drainage channels, all carefully kept in the best of repair.  The more level areas, too, in each of the three countries, have been similarly thrown into water level basins, comparatively few of which cover large areas, because nearly always the holdings are small.  All of the earth excavated from the canals and drainage channels has been leveled over the fields unless needed for levees or dikes, so that 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.

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 large, through the persistent repetitions which have prevailed for centuries.  If the yearly application of such water to the rice fields is but sixteen inches, and this has the average composition quoted by Merrill for rivers of North America, taking into account neither suspended matter nor the absorption of potassium and phosphorus by it, each ten thousand square miles would receive, dissolved in the water, substances containing some 1,400 tons of phosphorus; 23,000 tons of potassium; 27,000 tons of nitrogen; and 48,000 tons of sulphur.  In addition, there are brought to the fields some 216,000 tons of dissolved organic matter and a still larger weight of dissolved limestone, so necessary in neutralizing the acidity of soils, amounting to 1,221,000 tons; and such savings have been maintained in China, Korea and Japan on more than five, and possibly more than nine, times the ten thousand square miles, through centuries.  The phosphorus thus turned upon ninety thousand square miles would aggregate nearly thirteen million tons in a thousand years, which is less than the time the practice has been maintained, and is more phosphorus than would be carried in the entire rock phosphate thus far mined in the United States, were it all seventy-five per cent pure.