40 
Table XVI. — Effect of limed and unlimed soil on the availability of the phosphoric acid 
of guanos. 
Kind of soil. 
Efficiency of phosphoric acid 
in guanos compared with 
that of acid phosphate =100. 
Gain (+) 
or loss 
Source of phosphoric acid (P2O5). 
Both 
applied 
to 
unlimed 
soil. 
Both 
applied 
to limed 
soil. 
Guanos ap- 
plied to 
limed soil, 
acid phos- 
phate to un- 
limed soil. 
efficiency 
caused 
by 
limmg. 
Guano No. 797A 
Clay 
50 
8 
21 
17 
48 
26 
13 
4 
29 
8 
29 
50+ 
93 
30 
15 
4 
13 
15 
5 
5 
6 
47 
12 
23 
5 
63 
9 
22 
1 
1 
51 
40 
9 

8 
15 

2 
3 
30 
7 
27 
2 
38 
90 
4 
13 


31 
—10 
Guano No. 811 A 
Sand 
+ 1 
Guano No. 842 
Guano No. 851 
do 
do 
-21 
— 9 
Do 
Clay 
—33 
Guano No. 860 
Sand 
—26 
Guano No. 889 
Guano No. 923 
do 
do 
-11 
— l 
Guano No. 957 
Guano No. 966B 
Do 
do 
do 
Clay 
+ 1 
- 1 
— 2 
Guano No. 975 
Guano No. 977 
do 
Sand 
-48+ 
—55 
Do 
Clay... . 
Bone meal 
Sand 
31 
57 
5 
29 
59 
—27 
Do 
Clay 
—44 
Floats 
Sand 
— 5 
Do 
Clay 
—29 
Slag 
Sand 
—28 
1 
The third column of Table XVI shows the efficiency of the different 
materials relative to acid phosphate when both acid phosphate and 
the materials were added to the unlimed soil ; the fourth column gives 
efficiencies relative to acid phosphate in the limed soil. A comparison 
of results in the third and fourth columns shows whether the efficien- 
cies of bone meal, floats, slag, and guanos have been decreased more 
or less than the efficiency of acid phosphate by liming. As the avail- 
ability of acid phosphate was reduced in the limed soil, a comparison 
of values in the third and fourth columns does not give the absolute 
gain or loss in availability produced by liming, but the loss relative 
to that suffered by acid phosphate. 
In the fifth column are calculated the efficiencies of guanos, etc., 
in the limed soil relative to acid phosphate in the unlimed soil. A 
comparison of values in the third and fifth columns, therefore, gives 
the absolute gain or loss produced by liming in efficiency of the 
materials. This absolute gain or loss is expressed in the sixth 
column. 
It is apparent (by comparing values in the third and fourth col- 
umns) that the efficiencies of guanos Nos. 81 1A, 923, 957, and 966B 
were depressed less by liming than the efficiency of acid phosphate, 
while the efficiencies of bone meal, floats, and all other guanos were 
depressed to a much greater extent than that of acid phosphate. 
The efficiencies of slag and acid phosphate were affected about 
equally. 
