6 
COMPARATIVE EXPERIMENTS ON THE EFFECT OF 
According to these results the yield had been considerably 
increased by all the kinds of phosphatic fertilizers applied, but the 
double doses of these manures, though causing a far larger produce 
than the single ones, did not display their full action. Hence we 
must exclude the figures obtained with the larger doses of phosphates 
from further consideration, while those with the smaller ones will 
furnish a sufficiently reliable basis for a judgment on their relative 
action on the increase of the crop. Assuming the increase of crop 
caused by ioo grms. of the smaller dose of phosphoric acid in the 
form of superphosphate to be ioo, we obtain the following figures 
for the relative effect on the production of dry matter. 
Double superphosphate 
Steamed bone dust . 
Precipitated calcium phosphate 
Crude bone dust .. 
Raw crushed bones . 
Thomas phosphate. 
Bone ash. 
I oo.o 
80.1 
60.2 
545 
537 
48.5 
19.6 
Before entering into a discussion of these results we may consider 
the proportions of phosphorie acid consumed by the barley plants 
from the soil and manure, as found by the analysis of the crop. 
Phosphoric acid per plot. 
In the 
manure. 
gnus. 
I11 the 
crop. 
grms. 
Consumed fro 
Grms. 
m the manure. 
Per cent of 
the phos¬ 
phoric acid 
applied. 
No phosphatic manure 
O 
O.I29 
— 
— 
Double superphosphate ... 
1-413 
°-433 
0.304 
21-5 
99 99 
2.826 
o -573 
0.444 
— 
Steamed bone dust . 
1.696 
O.4IO 
0,281 
16 6 
99 99 99 . 
3392 
0.547 
0.418 
— 
Precipitated calcium phos. 
2.120 
O.42I 
O.292 
13-8 ' 
99 99 :> 
4.24O 
0529 
0.400 
— 
Crude bone dust. 
1.696 
°-333 
O.209 
I2.4 
99 99 99 . 
3392 
0.501 
0.372 
— 
Raw crushed bones . 
1.696 
0-343 
0.214 
12.6 
>1 99 99 . 
3-392 
0.469 
0.340 
— 
Thomas phosphate . 
2.120 
0.407 
0.278 
1 3-1 
” 9} . 
4.240 
0-536 
0.407 
— 
Bone ash . 
2.826 
0.270 
0.141 
50 
99 99 . 
5652 
o -393 
0.264 
— 
