FERTILIZERS FOR COFFEE IN PORTO RICO 29 
one sodium nitrate group — that receiving the lightest application. 
The best foliated sodium nitrate group averaged 23 per cent more 
than the check in number of leaves per tree, whereas the ammonium 
sulphate groups surpassed the check by 99 and 112 per cent. In the 
corresponding leaf weights, the best sodium nitrate group was ahead 
of the check by 50 per cent, whereas the ammonium sulphate groups 
surpassed it by 145 and 147 per cent. In weight of woody growth, 
the best sodium nitrate group was heavier than the check by 31 per 
cent, whereas the ammonium sulphate groups averaged 77 and 113 
per cent heavier than the check. The benefit from ammonium sul- 
phate was most pronounced and that from sodium nitrate decidedly 
less in comparison. 
In another test, begun in 1923 to compare further the effects of 
ammonium sulphate and sodium nitrate and to show how frequency 
of application of the latter and the addition of sulphur might affect 
its action, three series of forty 5-gallon containers were each filled 
with heavy clay, river loam, and ocean beach sand, respectively. In 
August, 1923, seed from a single tree of the Padang variety of Ara- 
bian coffee was planted, and in November, 1923, three seedlings (later 
thinned to two) were set in each container. At three weeks after 
setting, it was observed that many seedlings were damping off badly 
in the river loam, but that none were so affected in the sand or clay. 
Numerous seedlings in the loam had, therefore, to be reset. 
Each soil group of 40 cans comprised 10 receiving 8 grams of 
ammonium sulphate semiannually; 20 receiving the same quantity 
of nitrogen in the form of sodium nitrate (10 in semiannual appli- 
cations of 10 grams, and 10 in monthly applications of 1.7 grams) ; 
and the remaining 10 cans which received no nitrogen. Half the 
cans in each division, excepting that receiving ammonium sulphate, 
were given, in the form of flowers of sulphur, semiannual applica- 
tions of sulphur equal to that carried in 8 grams of ammonium 
sulphate. The semiannual applications were made from January 
3, 1923, to January 3, 1925, inclusive, and the monthly applications 
from January 3, 1924, to June 3, 1925. 
At less than two months after setting, the plants in sand were 
unsatisfactor}^ in appearance. One month following the first ferti- 
lizer application the plants receiving no nitrogen were noticeably 
very yellow in contrast with the green of all others, including plants 
receiving sodium nitrate in very small applications. At this time 
the plants in clay made the best appearance, and those in sand the 
poorest. At one year after setting, less than 1 plant in 5 of 
those in sand still retained foliage, and those which had not died 
had made very little growth. In July, 1925, when the test was 
brought to a close, all plants in sand, except one were dead. The one 
exception measured 131/2 inches in height, and had only four leaves. 
Nitrogen and sulphur had proved entirely inadequate for the devel- 
opment of young seedlings in sand. 
On account of the widespread disease infection in the loam, which 
retarded growth or killed many of the trees, the conditions for a 
study of the comparative effects of fertilizer were much less uniform 
than was the case with the healthy trees in the clay. Data from 
trees grown in the loam, although less reliable, show some interesting 
points of agreement with the former, and are given in Table 14. 
