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2.53 kilos of ammoniacal nitrogen, 1.42 kilos of phosphoric acid, 
and 1.31 kilos of assimilable potash is necessary, assuming that 
at the beginning these constituents of the soil are entirely lacking. 
The assimilation factor of ammonium sulphate was found to be, 
for nitrogen, 62% ; of superphosphates, for phosphoric acid, 
24% ; and of potassium carbonate, for potash, 50%. 
As 111 the stations investigations, nitrogen appeared to be the 
controlling factor in rice fertilization, it would be pertinent here 
to offer reasons for the results obtained in Japan. The import- 
ant role of the nitrogenous manures in soil fertilization has long 
been recognized in Japan, and perhaps nowhere else are nitrogen- 
ous fertilizers used to such an extent as there. Heavy green- 
mannring and composting are the universal practice, and owing 
to it, rather than to the natural supply of nitrogen in the soil, 
(which otherwise must long ago have become exhausted) are 
due the results which have been mentioned. 
The important point for ns is this : After centuries of heavy 
cropping the paddy fields of Japan have each year become more 
fertile, especially so in the most essential and expensive nutrient 
material, nitrogen. Hawaiian rice lands, on the other hand, 
are becoming more and more impoverished each year, lacking 
particularly nitrogen. The writer believes that the only rational 
remedy is the adoption of the Japanese practice of adding humus 
and other nitrogenous matter to the soil in the form of green- 
manures, composts and other organic fertilizers, with crop rota- 
tion and the emergence of the soil for at least half the year, 
during which time the substitute crop would preferably be of 
such a nature to require inter-tillage throughout its growing 
season. Reference will be made later to rotation crops in Japan 
and their management. 
While we have demonstrated the stimulating effects of am- 
monium sulphate it is questionable whether increased yields can 
be obtained continuously from this source alone. The Japanese 
investigators, with whom I conversed on the subject, seemed 
to doubt it. While as a matter of fact, they demonstrated early 
the greater efficiency of ammonium sulphate, as compared with 
sodium nitrate, calcium cyanide and other concentrated nitro- 
genous fertilizers, it has been found that an extensive and con- 
tinuous use of these fertilizers results in an altered physical con- 
dition of the soil, which may be followed by serious deteriora- 
tion of its mechanical and chemical construction. As we have 
repeatedly proved that sulphate of ammonia is more available 
than nitrate of soda in rice fertilization, the question arose as to 
the form in which nitrogen is assimilated by the rice plant in sub- 
merged cultures. Drs. Daikuhara and Imaseki, of the Central 
Experiment Station, who have been closely connected with the 
Japanese investigations, are thoroughly satisfied that the rice 
plant freelv assiniilates its nitrogen as ammonia. This was 
proved by the fact that the plants thrive in the presence of am- 
