May 19,1923 Nitrogenous Fertilizers Influencing Chlorosis in Rice 629 
may indicate that denitrification processes were rapid enough to prevent 
the accumulation of considerable amounts of nitrate nitrogen. It is 
assumed, however, that in this experimental work the nitrification of 
ammonium sulphate was so greatly inhibited that the plants which were 
groym in pots treated with that compound derived the greater part of 
their nitrogen from the ammonium radicle. Nitrogen in the form of 
nitrite did not appear in significant quantities in any pot. 
EXPERIMENT II.—A COMPARISON OF AMMONIUM SULPHATE AND 
AMMONIUM PHOSPHATE TO DETERMINE THEIR INFLUENCE ON 
THE DEVELOPMENT OF CHLOROSIS IN RICE 
No direct method having been devised to eliminate the effect of the 
basic residues of the nitrate fertilizers in this soil, in order to test the 
effect of nitrate nitrogen on the development of chlorosis it was planned 
to determine whether or not resistance to chlorosis was characteristic of 
plants grown with ammonium compounds. 
Thirty-four pots were prepared in the same manner as were those in 
experiment I. Potassium sulphate (K2SO4) was applied in sufficient 
amounts to furnish 2 gm. of potash (KjO) to each pot, and phosphoric 
acid (H3PO4) and ammonium sulphate [(NH4)2S04] were used as sources 
of phosphorus and nitrogen in one-half of the number of pots, while 
monoammonium phosphate (NH4H2PO4) was used to supply the same 
nutrient elements in the other half. Nitrogen in the amount of 1.25 
gm. was added to each pot, and phosphorus was furnished in the amounts 
shown in Table II. The ammonium phosphate treatments were supple¬ 
mented with ammonium sulphate to maintain the uniform quantity of 
nitrogen per pot. Plantings were made as in the former experiment, 
and five plants were selected from the seedlings to remain in each pot. 
The spraying was conducted as in experiment I. The results are given 
in Table II. 
