4 BULLETIN 31, PORTO RICO EXPERIMENT STATION 
As the plats were small, each point of the curves in Figure 2 
showing the effect of fertilizers on growth, was determined by the 
average of the plats in two divisions. The stimulation to growth 
furnished by the NK combination is here very evident, and the 
depressing effect of nitrogen when heavily applied and unaccom- 
panied by potash is equally pronounced. The curves for trunk 
diameter and for yield are very similar and tell practically the 
same story. Growth and yield are closely correlated. 3 
The trees began fruiting in 1916. The crop was verv small, and 
counts of the cherries averaged 106 to the tree for the planting as a 
whole. Thirteen plats produced more than the highest check plat. 
Eleven of the thirteen received nitrogen singly or in combination, 
and the section receiving the nitrogen produced over twice as many 
cherries as were produced by the check section. If inference were 
to be drawn as to the effect of fertilizer on the very small initial 
Co J f/ry^p/rY-fAP^] (w) 
\ P/r ) \ A/r J ( * J\ A/P/r ) 
006000 
( O )\ p K f\ * )( Nf * )( N * ) 
Fig. 1. — Average trunk diameter per plat in relation to the fertilizer applied, the plats of 
each division ranked according to trunk diameter, horizontal lines joining plats of equal 
rank. Key to figures, showing fertilizers applied. Symbols are combined to indicate 
fertilizer combinations. The fertilizer contained 7 per cent nitrogen, 10.5 per cent 
phosphoric acid, and 14 per cent potash 
crop it would be thought that nitrogen increased early production. 
The freshly picked cherries of subsequent crops were weighed and 
the weights were recorded in grams. 
The first important production was made in 1917 when the crop 
yielded an average of 971 grams (2 pounds 2 ounces) of cherries, 
which is equivalent to 5 and a fraction ounces per tree of dried coffee 
beans with the parchment removed. The average production per 
tree in 1924 was the equivalent of about 11/2 pounds of dried coffee 
beans with the parchment removed. The yields of these two crops 
and for the 8-year period 1917-1924 as a unit are graphically shown 
in Figures 3, 4, and 5, and the data for the 8-year period are given 
in Table 2. 
3 " There is a hijjh degree of correlation between trunk circumference and yield of fruit 
in apple trees." Waring, J. H. The probable value of trunk circumference as an 
ADJUNCT TO FRUIT YIELD IN INTERPRETING APPLE ORCHARD EXPERIMENTS. Amer. SOC. Hort. 
Sci. Proc, 1920, p. 179. 
