614 Philippine Journal of Science 1920 
proportions of these salts tested. There is thus no relation, in 
the present tests, between low yields of tops and the proportion 
of either the potassium or the phosphate salt. 
The lowest yield obtained with any of the cultures, exclusive 
of the control, had a relative value of 21. This lowest yield, 
indicated on the diagram by large circles, was obtained with 
three cultures—R1C1, R3C1, and R6C3. The first two of these 
cultures giving lowest yields were characterized by the lowest 
proportion of ammonium sulphate and relatively low propor- 
tions of primary calcium phosphate. The third culture, R6C3, 
had a much higher proportion of primary calcium phosphate (0.6 
of the osmotic value of its salt mixture) and a somewhat higher 
proportion of ammonium sulphate (0.3 of the total value of 
its salt mixture). The slight improvement in growth resulting 
from the addition to the soil of these poorest salt proportions 
is shown by the fact that the average yield of tops from the 
control cultures (lacking fertilizer altogether) had a relative 
value of 19, as compared with the lowest value of 21 from the 
cultures supplied with the poorest fertilizer mixtures. This 
difference is probably not significant, and the most poorly fer- 
tilized cultures may be considered as about equal to the controls. 
Relative dry yields of grain.—The relative yields of grain 
are shown on the triangular diagram of fig. 3. Since it is the 
grain that is the commercial product of rice, the grain yield may 
be considered the most valuable growth criterion for this plant. 
As in the preceding diagram (fig. 2), the area of high yields 
is denoted by small crosses, areas of low yields by small circles, 
and the highest and the lowest yields are indicated by a large 
cross and by large circles, respectively. In its general charac- 
teristics this diagram for grain yields is very similar to the 
one for top yields. The regions of high, medium, and low yields 
on the diagram, fig. 3, correspond rather closely with those of 
fig. 2, thus showing that the several sets of salt proportions 
affected grain and top yields in a very similar manner. The 
area of high grain yields is confined to the right-hand corner 
of the diagram; corresponding to the highest proportions of 
ammonium sulphate. High yields of grain were definitely cor- 
related, in these tests, with salt mixtures that contained high 
proportions of ammonium sulphate, and were never obtained 
when this salt made up less than 0.4 of the total osmotic value 
of the salt mixtures employed. As in the case of top yields, 
there was no clear relation, however, between grain yields am 
the proportions of either of the other two salts. Although high 
