May 19,1923 NUrogeiwus Fertilizers inflmncing Chlorosis in Rice 63 7 
The samples analyzed represent the entire plant above ground. The 
dry matter produced under the influence of each treatment was found to 
vary considerably, especially in those pots which received calcium 
nitrate, and the results of the analyses are therefore weighted in propor- 
tion to ^e amount of dry matter produced in the respective pot for the 
calculation of the average. 
ANALYTICAL METHODS 
The analytical methods used were essentially those prescribed by the 
Association of Official A^icultural Chemists.* 
Nitrogen was determined by the Gunning method, sodium sulphate 
being used in place of potassium sulphate. In order to determine the 
ash and its constituents, the material was charred over a low flame the 
sample was weighed, leached with dilute hydrochloric acid, and then fil¬ 
tered and washed on a tarred Gooch crucible having a pad of ash-free filter 
paper. The insoluble residue consisting of silica and carbon was dried 
and weighed and the carbon was burned off. The ash percentages were 
calculated from the weight of the original incinerated material by sub- 
tr^ting therefrom the loss of weight due to the ignition of the carbon. 
Carbon dioxid in the ash was not determined on account of the small 
quantity of material available. The quantity of silica reported is the 
sum of the weights of insoluble silica and of that in the hydrochloric 
acid extract which was obtained by evaporation and dehydration. Iron 
was determined by permanganate titration after it was reduced with 
zinc and by the Reinhardt method. The results obtained by each method 
were in agreement. 
DISCUSSION OF results OF ANALYSIS 
. Table IV discloses some results which may have a positive significance 
in showing the influences causing the chlorosis in experiment III. Table 
III shows that the nitrates had practically disappeared from the soil 
water at the time of the second cutting, and Table IV shows that a 
marked decrease in the percentage of nitrogen in the plant occurred 
during the period between the first and second cutting, those plants 
which had received nitrogen as calcium nitrate having gained 0.36 per 
cent of nitrogen in the increment of dry matter, while the plants in the 
other two series showed a loss of total nitrogen. 
If, therefore, the production of basic residues by the assimilation of 
the nitric fertilizer salts produced in the soil a condition that prevented 
the absorption of iron, or in the plant a condition which prevented the 
utilization of iron for the development of chlorophyll, the influence must 
have been removed before the plants in experiment III were ready for 
the second cutting, and at a time that was approximately coincident 
with the recovery of the plant from chlorosis. 
A comparison of the average results of the iron determinations indicates 
that, in those plants which received calcium nitrate, the first cutting of 
the plants had less iron in the dry matter, in the ash, and in the silica- 
free ash than was found in the same components of the green plants 
grown with the other treatments. In the second cutting the chlorotic 
plants had the higher content of iron in the dry matter; and while the 
rTnTTTR?T METHODS OF ANALYSIS, ASSOCIATION OF OFFICIAL AORI- 
® ^ compiled by the committee on revision of methods. U. S. Dept Agr. Bur 
Chem. Bui. 107 (rev.), 272 p., 13 fig., 1908. Reprinted 1912. ^ 
