May 19.1923 Nitrogenous Fertilizers Influencing Chlorosis in Rice 6 ^ 1 
In the original plan this test was to be conducted so that results could 
be obtained in duplicate, but 42 days after they were sown the plants 
under the influence of the different treatments showed such marked 
differences that it was deemed advisable to cut one-half the series in 
order that any tendency toward recovery might not deprive the writers 
of data showing the effect on plant growth of extensive chlorosis. At 
the time of the first cutting the plants in both pots in which the treat¬ 
ments had been duplicated were fairly uniform in size and appearance, so 
the probable error of the results obtained from the first cutting is small. 
The weights of the plants that were cut when they were in bloom 72 
days after planting are only approximately representative of the effect 
of the treatment because of the extreme variability in the size of the 
plants in many of the pots. In general, the variation was greatest in 
those pots showing the most severe cases of chlorosis, and it was appar¬ 
ently due to the unexplained difference in the tendency of individual 
plants toward recovery and normal growth. In pots No. 30 and 32 the 
chlorotic condition was so severe that some of the plants became dis¬ 
eased at the bud before they made any appreciable growth. The 
yields recorded for these pots represent only those plants which survived’ 
and made considerable growth ^ter recovery. 
As was true in experiment I, the effect of spraying with ferrous sul¬ 
phate was only partly successful in overcoming chlorosis on account of 
the nature of the leaf surface. That either the iron applied was diffused 
throughout the leaf or that the effect of the partial development of green 
color was to aid the plant toward natural recovery was apparent soon 
after the first series of plants was cut when the spotted surface of the 
leaves of the remaining sprayed plants developed a striped appearance. 
By reference to Table II it may be seen that, regardless of the difference 
in fertilizer treatments, the plants that were sprayed were quite uniform 
in appearance, although the plants grown with ammonium phosphate 
were not equal in weight to those grown with ammonium sulphate. 
The results obtained from experiment II show that the conditions 
causing the development of chlorosis were not necessarily induced by the 
presence of nitric nitrogen; nor were they traceable to the presence of 
an unassimilable basic radicle in the fertilizer salts used, in this case the 
indication being that chlorosis may have been caused by the precipita¬ 
tion of iron in the soil or in the plant by the phosphate ion liberated 
when the ammonium ion was assimilated at the more rapid rate. 
The explanation is not definitely justified by the data at hand because 
it was not possible, owing to the small quantity of material available, to 
obtain analytical results showing the relative quantities of nitrogen and 
phosphorus assimilated. Moreover, it is not certain that in a calcareous 
soil ammonium phosphate would remain as such for any great length of 
time. The chlorosis which occurred in the presence of ammonium phos¬ 
phate was much more severe than that which resulted from the use of 
sodium nitrate, but the plants grown with the former compound responded 
much better to spraying with ferrous sulphate and apparently tended 
toward a more complete recovery in the later stages of growth than did 
those grown with sodium nitrate. 
