22 
BULLETIN 31, PORTO RICO EXPERIMENT STATION 
ing three pairs of true leaves was set in each container on April 28. 
Measurements, made a month later, showed that the plants had at- 
tained a height of between 5 and 6 inches. All were green and 
apparently in vigorous condition. Subsequent measurements were 
made every three months. 
Fertilizer, at the rate of one-twentieth pound per pot per appli- 
cation, was given May 28 and November 28, 1914, and June 3, 1915. 
The basal formula used was nitrogen (7 per cent), phosphoric acid 
(10y 2 per cent), and potash (14 per cent). In addition to the com- 
plete fertilizer, the seedlings received nitrogen, phosphorus, and 
potash in combinations of two and singly. Where an incomplete 
fertilizer was applied each element was the equivalent of the same 
element applied in the complete fertilizer. 
The fertilizer carriers were ammonium sulphate, acid phosphate, 
and potassium chloride in the first application, and ammonium sul- 
phate, acid phosphate, and potassium sulphate in the two subse- 
quent applications. Each treatment was given in triplicate. In 
addition to the regular check lot, three containers were filled with 
soil dug about 50 yards distant from the first, and near better coffee. 
This lot is marked " O' " in the diagram and tables. 
At the time of the first fertilizer application the difference in com- 
bined height between any 2 groups of 3 trees was y 2 to 1 inch 
only. Nine months later each group receiving nitrogen surpassed 
the check in height and all others fell below it. The 4 nitrogen 
groups averaged 97 inches high and the other five 83.7 inches. From 
November 28, 1914, to February 27, 1915, each group receiving nitro- 
gen increased in height between 31 and 34 inches, whereas the others 
for the same period showed an increase of only 18 to 23 inches. 
From May 28 to August 28, 1915, the 4 nitrogen groups increased 
in height 13, 14, 18%, an d 19 inches, respectively, whereas of the 5 
groups receiving no nitrogen 3 increased 1, 3, and 7% inches, respec- 
tively, and 2 failed to increase. The difference in height between 
the check and the other groups is shown in Table 9. 
Table 9. — Difference in height between check and fertilized groups of three 
young coffee trees each groivn in cans 
Date of measurement 
Fertilizer applied 
1914 
1915 
May 28 
Aug. 28 
Nov. 28 
Feb. 27 
May 28 
Aug. 28 
Nov. 27 
N 
Inches 
+1 
+A 
+1 

+1 

+y 2 

+y 2 
Inches 
-6 
-4 
-3H 
+2 

+2 
+4^ 

-8 
Inches 
-ioy 2 

-VA 
-4 
-4 

-9 
Inches 
+\Vi 
-3 
+20 
+5V 2 
-2A 
+9 

-&A 
Inches 
+WA 
-m 
+2 
+27H 
+12 
-Vt. 
+20 

-7Vz 
Inches 
+2bV 2 
+A 
+1 
+40J^ 
+30H 
+6 
+37H 

-m 
Inches 
+18 
P 
-5 
K. 
-6 
NP . 
+32 
NK. 
+2VA 
PK.._. 

NPK... 
+31H 
0. 

0' 
-15H 
The effect of nitrogen for increasing growth is clearly evident. 
Both phosphoric acid and potash, with the former leading, evidently 
still further increased growth when used in combination with ni- 
