iS 
COMPARATIVE EXPERIMENTS ON THE EFFECT OF 
Relative 
Relative 
Relative 
a isimilability. 
increase of crops. 
mamirlal value, 
Double superphosphate 
. IOO 
IOO 
IOO 
Steamed bone dust 
. 78-4 
00 
C <0 
HI 
i’recipitated calcium ph 
osphate. 77.7 
719 
75 
Crude bone dust. 
. 120.1 
102.4 
11 a 
Raw crushed bones ... 
. 137-0 
107.3 
123 
Thomas phosphate ... 
. 53-5 
42.6 
48 
Hone asli . 
. 42.7 
34-7 
:to 
The phosphoric fertilizers applied in 1890 displayed according 
to the preceding results further distinct effect after they had been 
for nearly 2 years in soil from which crops were continually taken. 
Doubtless, this condition will last for a considerable time yet, and 
it will, therefore, be most interesting to continue the experiments 
on the same plan for several seasons to come. 
Upon comparing the figures given for the relative increase of 
crop and the relative assimilability, we notice that the differences 
between them became in some cases gradually wider, the longer 
the phosphates had been in the soil. This need not surprise us, 
since it is plain that the later crops find only the most insoluble 
remainders of the phosphatic fertilizers, which become available 
but slowly, and are always consumed somewhat too late to partici¬ 
pate to their full capacity in the production of arganic matter. It 
is evident that this must be particularly noticeable with the large 
doses of phosphates, for which the following figures result from a 
calculation based on the assumption that the relative action on the 
increase of crop and the quantities of phosphoric acid consumed 
from the large dose of the superphosphate is 100. 
Relative 
increase. 
4 crops. 
Relative 
Consumption 
ol phosphoric 
acid. 4 crops. 
Relative 
niaiiurial 
value. 
Double superphosphate . 
... IOO 
IOO 
IOO 
Steamed bone dust . 
... 82.3 
90.0 
86 
Precipitated calcium phosphate... 
... 67.3 
80.0 
74 
Crude bone dust. 
... 113.7 
150.8 
132 
Raw crushed bones . 
... 104.5 
141.2 
123 
Thomas phosphate . 
... 49.4 
555 
52 
Bone ash . 
... 40.5 
49.9 
45 
