FERTILIZERS FOR COFFEE IN PORTO RICO 
27 
trees, the ammonium sulphate groups appearing to be adversely 
affected by the fertilizer in proportion to the quantity applied. 
Five months later, however, these groups had a noticeably darker 
leaf color than the others, and a month later still this difference was 
very pronounced. 
Since the ammonium sulphate seemed so much more favorable in 
its effect than the sodium nitrate, it was deemed advisable to divide 
the group receiving the latter into two groups, one of which received 
sulphur in the form of flowers of sulphur in January and May, 1923. 
In the case of the two groups receiving the lighter application of 
sodium nitrate one application of sulphur was equivalent to the sul- 
Fig. 15. — Growth of young coffee trees in cans following applications of nitrogen and 
of lime 
phur in 8 grams of ammonium sulphate ; and, correspondingly, in the 
case of those receiving the two heavier applications of sodium nitrate 
it- was equivalent to that in 12 grams of ammonium sulphate. The 
first application was made whenthe test was half over, and the total 
quantity of sulphur applied was less than that carried in the series 
of ammonium sulphate applications. For this reason it is not deemed 
necessary to give the matter further consideration than to say that 
the results were not in agreement, the three groups receiving sulphur 
being superior to their checks, and the fourth inferior, on the termina- 
tion of the test in September, 1923. The average superiority of the 
sulphur- treated plants over the check plants for the whole period was 
