12 
COMPARATIVE EXPERIMENTS ON THE EFFECT OF 
Relative effect 
on the production 
of dry matter. 
Double superphosphate . loo 
Steamed bone dust . 81.0 
Precipitated calcium phosphate . 66.6 
Crude bone dust. 67.0 
Raw crushed bones . 58.5 
Thomas phosphate . 41.9 
Bone ash . 23.3 
The quantities of phosphoric acid consumed from the original 
manure by the second crop, are shown in the following table : 
Phosphoric acid per plot. 
In the 
original 
manure. 
grms. 
In the 
crop. 
grms. 
Consumed from the 
manure by the 
2nd crop. 
Consumed 
by the two 
first crops, 
per cent of 
the phos¬ 
phoric acid 
applied. 
grms. 
per cent 
of the 
phosphoric 
acid 
applied. 
No phosphatic manure ... 
— 
°.°93 
— 
— 
— 
Double superphosphate ... 
M13 
0.247 
0.154 
10.8 
32.3 
it a 
2826 
0.278 
0.185 
— 
— 
Steamed bone dust. 
1.696 
0.217 
O.I24 
7-3 
23-9 
a a a . 
3-392 
0.320 
O.227 
— 
— 
Precipitated calcium phos. 
2.120 
0.269 
0.176 
8-3 
22.1 
>» a a 
4.240 
0-327 
0.234 
— 
— 
Crude bone dust . 
1.696 
0.275 
0.182 
IO.7 
23.x 
it it H . 
3-392 
0.484 
0.391 
— 
— 
Raw crushed bones. 
1.696 
0.259 
0.166 
9.8 
22.4 
}♦ >> it . 
3-392 
0-335 
0.242 
— 
— 
Thomas phosphate. 
2.120 
0.159 
0.066 
3 -i 
16.2 
it it . 
4.240 
0.215 
0.122 
— 
— 
Bone ash . 
2.826 
0.188 
0.095 
3-4 
8.0 
’5 >) . 
5-652 
0.258 
0.165 
— 
— 
If we would estimate the manurial value of the manures only 
from the quantity of nutrients consumed from them by plants, the 
above figures relating to the two first crops would indicate that the 
phosphoric acid in the form of steamed and crude bone dust, raw 
