Jan. 22, 1917 
Effect of Fertilizers on Oranges 
137 
that the small quantities being added increased the amount available to 
the tree to a point where it would be taken up in excess. No direct evi¬ 
dence was obtained, however, since the same quantity was applied in 
each case. 
THE EFFECT OF FERTILIZERS ON THE PHOSPHORIC-ACID AND 
POTASH CONTENT OF ORANGES 
Although this investigation was undertaken primarily to determine 
whether the fertilizers affected those characteristics of the orange usually 
considered in connection with its quality, the results obtained in the 
nitrogen determination suggested that work be undertaken in regard to 
the absorption of other elements of fertility. Accordingly, the phos¬ 
phoric-acid content was determined in the Valencia crop of 1914 and the 
navel crop of 1915. In the 1915 crop the percentage of potash was 
also determined. Table X presents the results. 
Tabi <3 X. —Effect of various fertilizers on the phosphoric-acid and potash content of 
Valencia and navel oranges 
Plot. 
Fertilizer applied. 
Per cent of 
phosphoric 
acid 
Valencia 
oranges, 
1914. 
Per cent of 
phosphoric 
acid navel 
oranges, 
1915- 
Per cent of 
potash 
navel 
oranges, 
1915. 
A 
Complete, nitrate of soda, blood, bone, sul¬ 
phate of potash.. 
0. OCO 
0.051 
0. 23 
B 
Check.. 
. 066 
. oco 
C 
Dried blood. 
OC 2 
• 23 
D 
Sulphate of potash. 
. 072 
. 063 
.056 
•055 
. O56 
. OCI 
E 
Steamed bone.'. 
22 
F 
Stable manure. 
OC2 
• 2 3 
.24 
. 24 
G 
Nitrate of soda, blood, and steamed bone. 
v • O52 
H 
Nitrate of soda. 
I 
Muriate of potash. 
• 
. 061 
• *00 
. 052 
. OC2 
i 
Superphosphate. 
. 058 
• 059 
ocn 
• 23 
• 23 
■ 23 
Bone and sulphate of potash. 
. OCI 
L 
Nitrate of soda. 
OC 2 
M 
Check... 
• 
. 060 
* 
OC2 
N 
Superphosphate. 
. 062 
• ^0 
0 
Stable manure and raw phosphate rock. 
•055 
. 0 S 7 
• '■'DO 
. 047 
. OCI 
• ^0 
• 23 
• 23 
• 23 
22 
P 
Steamed bone.. 
Q 
Complete, like A, except superphosphate in¬ 
stead of bone.... 
* 'O/ 
. 0^7 
. oco 
R 
Sulphate of potash. 
OC2 
S 
Dried blood. 
.056 
. OCO 
• 
.050 
OCT 
• 23 
• 23 
T 
Check. 
. U51 
There was no increase in the amount of either phosphate or potash 
in the fruit brought about by the quantities applied in this experiment. 
The averages from those plots receiving fertilizers are almost identical 
with those not fertilized. This gives further significance to the increase 
in nitrogen content brought about by nitrogen fertilization and sup¬ 
ports the view that nitrogen is the limiting factor in the production of 
oranges on this soil. 
