16,6 Espino: Salt Requirements of Young Rice Plants 463 
tus of the problem, however, and ended his discussion by empha- 
sizing the need for much more study along these lines; he said 
that “further experiments will be conducted to determine the 
correctness of this view,” but this promise has apparently not 
yet been fulfilled. 
Similar beneficial effects of ammonium sulphate upon rice 
plants were observed by Daikuhara and Imaseki,^® with pot cul- 
tures. They found that ammonium sulphate alone was superior 
to sodium nitrate alone and also to a combination of these two 
salts. 
From field experiments W. H. Harrison concluded that ni- 
trates were unsuitable for rice, but that ammonium compounds, 
or manures that yield ammonia under anaerobic conditions of 
fermentation, were of great value. J. B. Harrison,^® on the other 
hand, reported that the application of ammonium sulphate to field 
plats of rice resulted in a decreased yield. This lower yield, how- 
ever, was thought to be due to lodging, which occurred on account 
of the very luxuriant growth that took place in the plats sup- 
plied with ammonium sulphate rather than to any directly in- 
jurious effect of the salt. 
Further experimental evidence in favor of the idea that 
ammonium salts are good sources of nitrogen for rice is avail- 
able from later work by Kelley,^® who conducted a series of 
field trials. Ammonium sulphate was added to one plat and 
sodium nitrate to another, the addition being made before the 
time of planting. To the soils of other plats nitrogenous fer- 
tilizers were added from time to time during the development 
of the plants. The results agreed in indicating the superiority 
of ammonium sulphate over sodium nitrate. Kelley concluded 
that— 
a complete fertilizer proved no more effective than ammonium sulphate 
alone, whereas the application of both ammonium sulphate and potas- 
sium sulphate caused a decrease as compared with that obtained from 
ammonium sulphate alone. 
“ Daikuhara, G., and Imaseki, T., On the behavior of nitrate in paddy 
soils. Bull. Imp. Central Agr. Exp. Sta. Japan 1 (1907) 7-36. (Cited by 
Kelley, 1911.) 
“ Harrison, W. H., The principles of paddy manuring, Journ. Board 
Agr. Brit. Guiana 6 1 (1912) 37-40. Ibid. 6 2 (1912) 71-77. 
“ Harrison, J. B., Experiments with varieties of rice at the Botanic 
Garden, 1912, Journ. Board Agr. Brit. Guiana 7 (1913) 42-43. 
“Kelley, W. P., Rice soils of Hawaii: Their fertilization and manage- 
ment, Hawaii Agr. Exp. Sta. Bull. 31 U. S. Dept. Agr., Washington, D. 
C. (1914). 
