FERTILIZERS FOR COFFEE IN PORTO RICO 
31 
leaves, and also that sodium nitrate alone applied monthly was much 
more effective than when applied semiannually. 
At 18 months following the first fertilizer application, the leaves 
were counted and weighed, the heights were measured and trunks 
cut at the ground, and the woody growth above ground Avas weighed. 
Figure 18 graphically shows the development of the young trees in 
clay, expressed in percentages of the check. 
Of the trees grown in clay, the group receiving sodium nitrate 
monthly and sulphur in addition ranked first in number of leaves and 
in weight of both leaves and woody growth. In height there was 
little difference between this group and the two groups receiving 
ammonium sulphate and sodium nitrate, respectively, in semiannual 
applications plus sulphur. Considering the data as a whole, it is 
seen that these two latter groups tied for second place. The group 
receiving monthly applications of sodium nitrate but no sulphur fell 
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6 MONTHS /MONTH 
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6'*fc-3. 
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PHOSPHOSK ACIO 
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SULPHUR OOO ooooooo 
Fig. 18. — Development of young coffee trees as affected by the nitrogen carrier, frequency 
of application, and addition of sulphur. Data expressed in percentages of the check 
at close of test, July, 1925 
below these three leading groups in weight of both leaves and woody 
growth and in height, but in every particular it surpassed the group 
receiving in all an equal quantit}^ of sodium nitrate given in semi- 
annual rather than in monthly applications. The two groups given 
no nitrogen ranked below all others in every particular, the differ- 
ences in number and weight of leaves and woody growth being pro- 
nounced. The group receiving sulphur alone failed to equal the 
check, though this fact is presumably without significance. 
In both the cla}^ and the loam the group receiving sodium nitrate 
in monthly applications plus sulphur ranked first. Equal quantities 
of sodium nitrate proved much more effective in small monthly than 
in semiannual applications six times as large. The latter proved 
much less effective than equal quantities of nitrogen in ammonium 
sulphate. Nitrogen was least effective in semiannual applications of 
sodium nitrate alone, and all groups given nitrogen grew better 
than those to which it was not applied. 
