130 
Journal of Agricultural Research 
Vol. VIII, No. 4 
made on the juice, its specific gravity being determined by a spindle 
and calculated to 15 0 C. Total sugars, after inversion by Clerget’s 
method, were determined by the Bertrand method, and the sugar calcu¬ 
lated as reducing sugars. The acidity was determined by titration with 
N/10 alkali with phenolphthalein and the results expressed as anhydrous 
citric acid. The nitrogen was determined by the Gunning method. 
There was some variation in the results obtained from the different 
trees of a given plot, particularly in the percentage of sugar, but in those 
cases where notable effects were produced by the fertilizer used, as, for 
example, the nitrogen content, the variations were nearly always within 
the limit of experimental error. Table I presents the individual tree 
records of a plot chosen at random, to show the range of variation. 
The plot shown is F, fertilized with stable manure. 
Table I .—Composition of oranges from individual trees of a single plot 
No. 
Spe¬ 
cific 
gravity. 
Juice. 
Sugar. 
Add. 
Nitrogen. 
Phosphate 
(P2O5). 
Potash 
(K a O). 
F 282. 
F 283. 
F 284.. 
F 286.. 
F287. 
F288. 
Average. 
0.88 
.87 
.89 
.88 
.90 
.88 
- Percent . 
37-9 
40. 7 
39-8 
37-3 
42. I 
40. I 
Per cent. 
10. 74 
10. 40 
10. 46 
10. 47 
9.09 
9. 18 
Percent. 
1. 02 
’ .89 
i- °S 
•97 
.94 
• 9 i 
Per cent. 
0. 117 
. 116 
. 109 
• «3 
. 117 
. 121 
Per cent. 
0. 052 
. 050 
.051 
. 0<?2 
• 052 
. 0$2 
Per 
cent. 
0. 21 
•23 
•23 
•23 
00 
00 
39-6 
10. 06 
.96 
• ns 
. 0$2 
•23 
For the sake of brevity the data have been compiled by plots, the 
figures presented being merely the averages of the individual tree rec¬ 
ords obtained. These averages have been assembled with a view to 
facilitating comparisons of the effect of different fertilizers. In Tables 
II and III are presented the data from the check plots, those treated 
with nitrogen, potash, or phosphates only, and the complete-fertilizer 
plots. 
Under the conditions of this experiment, neither potash nor phosphate 
exercised any effect on the sugar content, but nitrogenous fertilizers, 
alone or in combination with potash and phosphate, depressed the sugar 
content. Averaging the figures for sugar in the two crops of each va¬ 
riety, the potash plots show 9.37 per cent, the check plots 9.36 per cent, 
and the phosphate plots 9.25 per cent. These variations are all within 
the limits of analytical error. The plots treated with nitrogen alone and 
those treated with complete fertilizer contained 8.85 per cent and 8.81 
per cent, respectively, or about 0.5 per cent less than the other plots. 
This is a recognizable difference and constant enough to be ascribed to 
the treatment. It is interesting to note that the effects are greater in 
the 1915 crops, which were harvested about two months later, than in the 
