Oct. 20, 1923 
Soil Reaction in Relation to Calcium Adsorption 
113 
initial concentration is low. This is due to the neutralizing effect of the 
acid-producing substance. Soil texture also has an influence on the 
result, shown by the fact that a certain amount of Ca(OH) 2 will not 
produce as great a change in the P H values in clay and silt soils as in 
sandy soils. Most soils in which the initial hydrogen-ion concentration 
corresponds to a P H value of 5.5 or less required about 5 tons equivalent 
of CaC0 3 per acre to approximate the hydroxyl-ion concentration usually 
found in soils of high calcium content. 
EXPERIMENT 23 .—TOTAL CALCIUM OP SOILS AND CALCIUM SOLUBLE IN 0.5N HYDRO¬ 
CHLORIC ACID AND 0.5N POTASSIUM CHLORID SOLUTIONS 
The soils used in Experiment 18 had been previously analyzed for total 
calcium in connection with the work of the State soil survey. The cal¬ 
cium soluble in 0.5N HC 1 and in 0.5N KC 1 solution was determined by 
digesting at room temperature for 24 hours. The data obtained are 
presented in Table XXIII. 
Table XXIII .—Total calcium and calcium soluble in 0.5N HCl and in 0.5N KCl 
Surface soil. 
Subsoil. 
Soil 
No. 
31 
27 
23 
25 
49 
11 
17 
33 
15 
13 
S 3 
5 i 
57 
47 
21 
39 
4 i 
19 
43 
35 
29 
45 
37 
55 
County. 
Allen. 
.... do. 
.... do. 
_do. 
Montgomery... 
Allen. 
Brown. 
Allen. 
Riley. 
Allen. 
Brown. 
Leavenworth. . 
Barton. 
Cherokee. 
Harper. 
Jewell. 
-do. 
Brown. 
Greenwood. 
Finney. 
Allen. 
Greenwood. 
Jewell. 
Gove. 
Soil type. 
Total 
0.5N 
HCl 
0.5N 
KCl 
Total. 
0.5N 
HCl 
0.5N 
KCl 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
Mgm. 
Oswego fine sandy 
25 
15 
15 
27 
21 
*3 
loam. 
Osage clay. 
43 
35 
36 
56 
50 
51 
Neosho silt loam.... 
39 
17 
16 
36 
36 
39 
Osage loam. 
50 
26 
25 
41 
28 
28 
Crawford loam. 
39 
18 
21 
38 
25 
3 i 
Summit silt loam.... 
37 
35 
33 
195 
195 
56 
Marshall silt loam . . . 
45 
3 1 
26 
57 
37 
38 
Summit silt loam.... 
37 
18 
16 
3 1 
17 
1 9 
Oswego silt loam.... 
64 
33 
3 i 
96 
74 
5 i 
36 
26 
26 
41 
3 i 
35 
Marshall silt loam . . . 
62 
3 i 
27 
7 1 
29 
33 
Brown loam. 
58 
33 
27 
59 
24 
27 
Greensburg sandy 
58 
26 
18 
134 
112 
33 
Oswego clay. 
77 
35 
33 
181 
154 
145 
Brown loam. 
42 
14 
11 
47 
!7 
16 
Lincoln clay. 
104 
42 
39 
172 
54 
44 
Colby silt loam. 
59 
27 
24 
96 
78 
45 
Osage silt loam. 
80 
59 
38 
128 
105 
54 
Crawford silt loam... 
49 
32 
29 
60 
57 
40 
Richland silt loam... 
81 
34 
26 
421 
139 
33 
Oswego silt loam.... 
82 
68 
5 2 
215 
209 
61 
Crawford clay. 
320 
321 
47 
3 ” 
434 
33 
Lincoln silt loam.... 
222 
192 
52 
15 ° 
136 
42 
Colby silt loam. 
183 
78 
34 
256 
285 
34 
The total calcium obtained by the fusion method was uniformly 
greater than the calcium soluble in either the HCl or KCl solutions, 
and the differences were more marked in soils of low calcium content. 
This means that the lower the calcium content the lower the relative 
solubility. In soils of comparatively low calcium content the amount 
soluble in a KCl solution was nearly the same as that soluble in a HCl 
