Oct. 20 , 1923 
Soil Reaction in Relation to Calcium Adsorption 
109 
EXPERIMENT 20.—COMPARATIVE POWER OF FOUR SOILS TO ADSORB CALCIUM FROM 
CALCIUM HYDROXID IN THE PRESENCE OF CALCIUM CARBONATE 
The amounts of CaC0 3 equivalent to the calcium adsorbed in Experi¬ 
ment 19 were calculated and added to the dry soil. Fifty cubic centi¬ 
meters of water was added to each bottle, the mixtures shaken for several 
hours, and then allowed to digest for one day. Ca(OH) 2 solutions were 
next added, and from this point on the experiment was performed like 
No. 19. The Ca(OH) 2 solutions were so adjusted that very nearly the 
same amounts of calcium were used per 10 gm. of soil as in the preceding 
experiment. The data obtained are presented in Table XX. The cal¬ 
cium adsorbed was calculated on the basis of the amounts added in the 
Ca(OH) 2 solutions. 
Table XX .—Adsorption by four soils in the presence of CaCo z of calcium from Ca (0H) 2 
Ca(OH)s 
NEOSHO SII,T LOAM. 
OSWEGO SILT LOAM. 
Calcium 
in extract. 
Calcium 
adsorbed 
from 
Ca(OH) 2 
Extract. 
Calcium 
in extract. 
Calcium 
adsorbed 
from 
Ca(OH) 2 
Extract. 
Mgvi. 
Mgm. 
Mgm. 
Ph- 
Mgm. 
Mgm. 
Ph- £ 
17-9 . 
3-6 
14.3 
9 - 53 
4. 6 
13-3 
8. 62 
21.3. 
4. 2 
17. I 
IO. 11 
4. 2 
17. 1 
8- 75 
25-4 . 
6. 0 
19.4 
IO. 72 
4. 2 
21. 2 
9. 18 
27-9 . 
7.0 
20. 9 
i°- 95 
4 - 7 
23. 2 
9. 64 
34-2 . 
10. 9 
23-3 
11. 40 
5 - 2 
29. 0 
io- 55 
40. 9. 
14. 5 
26. 4 
ii- 53 
6. 8 
34 - 1 
10. 97 
50.3 . 
20. 3 
30. 0 
11. 66 
10. 4 
39-9 
10. 36 
68.2. 
3 1 * 9 
36.3 
11. 90 
17. 2 
51.0 
11. 70 
BATES VERY PINE SANDY LOAM. 
BATES LOAM. 
17-9 . 
4 . O 
13-9 
8. 45 
5-4 
12. 5 
8. 72 
21.3. 
4 - 7 
16. 6 
9-37 
5-6 
15 - 7 
8. 77 
25.4 . 
4.8 
20. 6 
9.72 
5-4 
20. 0 
9. l8 
27-9 . 
5-7 
22. 2 
10. 06 
5-4 
22. 5 
9. 21 
34-2 . 
7.6 
26. 6 
10.97 
5- 6 
28.6 
10. 70 
40.9 . 
10. 0 
30-9 
11. 22 
6. 5 
34 - 4 
9. 60 
50*3. 
35 - 2 
ii- 53 
9.4 
40. 9 
II. 17 
68. 2. 
26. 0 
42. 2 
11. 80 
i 7 -3 
5 °- 9 
II. 63 
The P H values were not materially affected by the presence of CaC0 3 . 
The excess of the hydroxyl ions was so large as to mask the influence of 
the HC 0 3 and C 0 3 ions. The addition of CaC 0 3 under the conditions of 
this experiment did not change the relative adsorptive power of these four 
soils as found in Experiment 19. The presence of CaC 0 3 only slightly 
reduced the amount of calcium adsorbed from Ca(OH) 2 . In Experiment 
7 it was found that CaC 0 3 had practically no effect on calcium adsorption 
from Ca(OH) 2 . The only difference in procedure between Experiments 
7 and 20 was that in the latter case there was a longer contact for the 
CaC 0 3 in the presence of water. While the effect of this longer contact 
was small it is enough to suggest that calcium is taken very slowly from 
CaC 0 3 by the soil. The effect of long-time contact with CaC 0 3 was also 
shown in Experiment 3. 
