FERTILIZERS FOR COFFEE IN PORTO RICO 
21 
respectively, or a total of 11,928, and the yields from the three plats 
receiving sodium nitrate were 1,019. 102, and 164 cherries, respec- 
tively, or a total of 1,285 cherries, which was less than one-ninth the 
production made by the ammonium sulphate treated plats. 
The production, as well as the measurements of growth, indicated 
a favorable effect of the ammonium sulphate as compared with 
applications of sodium nitrate or lime. 
EXPERIMENTS IN LIMING 
A planting of more than 100 trees which were set in 1909 was 
divided into two plats to provide a site for liming experiments 
After the 1913 crop was harvested one plat was uniformly limed 
(probably four-fifths air-slaked and one-fifth quicklime) at the rate 
of little more than 3 pounds per square meter of surface. Previous 
to liming the soil was cultivated. Table 8 gives the yields during 
five vears. 
Table 8. — Yields of cherries before and after liming 
Year 
Liters 
1913 (before liming).. 1.08 
1914 (after liming) 1.23 
1915 1.85 
1916 1.33 
1917 2.38 
Total for 1914-1917 period 6.79 
6.86 
The }^ear preceding the application of lime the average yield per 
tree of the plat subsequently limed surpassed that of the check by 
9 per cent. With the yield of the check considered as 100 per cent, 
the yield of the limed plat for the years subsequent to lining was 
108 per cent for the first year, 94 per cent for the first two years 
(combined yield), 104 per cent for the first three years, and 101 
per cent for the first four vears. The results failed to show anv 
appreciable benefit from liming. 
Two other tests were made on a smaller scale, the trees being 
limed annually at the rate of 1 to 2 pounds per tree. The results 
were not in accord, one lot vielding more and the other less than its 
check. 
POT TESTS 
COMPLETE AND INCOMPLETE FERTILIZERS 
To learn the effect of fertilizers on yield under more controlled 
conditions than were possible in the field, several tests were made 
with coffee seedlings set in 5-gallon containers. In March, 1924. heavy 
red clay soil, removed to a spade's depth from a hilltop on which 
coffee had made poor growth, was placed in the containers, using 
coarse gravel in the bottom for drainage. A vigorous seedling hav- 
