FERTILIZERS FOR COFFEE IN PORTO RICO 7 
The highest yield for the eight-year period was made by the XK 
plat in the fifth division. This plat was fertilized at the heaviest 
rate, receiving 4 pounds per tree per application (1 pound 6% ounces 
ammonium sulphate and 1 pound 2 ounces potassium sulphate per 
tree per application), or 8 pounds annually of a 7:0:14 fertilizer 
combination. The last two yields from the plat were very high, 
averaging 2 pounds 15 ounces and 2 pounds 13 ounces, respectively, 
per tree per annum, of dried coffee beans with the parchment re- 
PO/NTS DET£eM/N£D BY T/9££S /N 
D/VS. /-2 2-3 3-4 
e/iT£ OF F£eT/UZ£e P£P TG££ P£# APPL/CAT/ON 
'/4-y a POUMD '/2-/POUMD /-2 POUHDS 
/aoo 
4-S 
2-4 POUNDS 
/700 
& /600 
/500 
/400 
/SOO 
/aoo 
^ HOO 
^ /OOO 
900 
300 
g 
8 
k 600 
^ soo 
% 
~ 400 
30O 
200 
/oo 
y 
s 
KEY TO 6MPH SHOW/NS FSBriUZEeS APPilED 
SyMSOLS ABE COMBMED TO /ND/CATE 
EEBT/L/ZEB COMB/HAT/OMS 
N/TB06EN\ %£% T£ 
L/r7E • 
PHOSPHOB/C AC/D 
POTASH H + + + + + + + + + 
SULPHUB OOO OO OOOOO 
^ 
1 
Fig. 3. — Average production per tree for the year 1917. South Field plats 
moved. This plat produced nearly three times as great a yield for 
the eight-year period as did the check in the same division. 
Contrasting all trees receiving any one element with those not re- 
ceiving that element, and considering the latter section as the check, 
it is seen that for the 1917-1924 period as a unit the nitrogen section 
surpassed its check in yield by 4 per cent, the phosphoric acid section 
fell below its check by 17 per cent, and the potash section surpassed 
its check by 82 per cent. Table 4 gives the average production for 
the trees for the 1917-1924 period. 
