6 5 8 
Journal of Agricultural Research voi. xxvii, No. 9 
Table XX .—Effect of diluting the soil solution by leaching when the solution is rich in 
calcium and magnesium; 1,000 gm. of soil , jo cc. fractions of percolate 
Percolate No. 
Total 
solids, a 
Percentage of constituents to total solids. 
Ca + Mg. 
HCO3 
2 
Cl. 
SO*. 
NOs. 
Total 
adds. 
1. 
37 - 58 
27. 1 
2. 0 
35-5 
0. 2 
5 -o 
42. 7 
2. 
26. 52 
35-2 
2-3 
40.9 
•3 
5 - 1 
47.6 
3 . 
21. 57 
36. 2 
2. 6 
41. 2 
•4 
4. 9 
49. 1 
4 . 
10. 95 
37 - 5 
4. 4 
44 - 7 
• 9 
6-3 
56.3 
5 . 
4-45 
28. 7 
3 -o 
42. 5 
4. 2 
5-9 
55-6 
6 . 
2. 82 
25- 5 
i- 5 
47. 2 
4-9 
2. 1 
51-8 
7 . 
2. 86 
22. 4 
.8 
44. 1 
4.0 
*•4 
5 o -3 
8... 
2. 04 
21 * 5 
i -3 
43 - 0 
5-9 
Tr. 
50. 2 
9 . 
1. 34 
24. 6 
2. 0 
38.0 
10. 2 
0 
50. 2 
10. 
.83 
22. 8 
3-6 
3 °. 2 
19. 8 
0 
53-6 
11. 
• 57 
19.4 
3-2 
23-3 
30-3 
0 
56.8 
12. 
.41 
21. 2 
6. 6 
7-5 
43 - 2 
0 
57-3 
13 . 
•32 
21. 6 
7-5 
5-3 
46.8 
0 
59-6 
14.. 
. 21 
24- 5 
5 
5-3 
45 - 7 
0 
62. 5 
15 . 
. 18 
20. 7 
9. 1 
2. 2 
40.3 
0 
51-6 
a In percentage of solution, including organic matter. 
The proportion of chlorin remained fairly constant until the tenth 
percolate when it began to decline rapidly. At this time the concentra¬ 
tion of the solution had been reduced from 37 per cent to 1 per cent. 
When the proportion of chlorin began to decline rapidly the proportion 
of carbonate and sulphate began to increase correspondingly. This 
sequence of changes in the character of the solution obtained from 
the same sample of soil as a result of leaching illustrates what may go 
on in a field that is being reclaimed by the same process. The leaching 
results not only in reducing the concentration of the soil solution but 
also in changing its character. This change in the character of the soil 
solution appears to be associated with what may be termed the relative 
motility of the various constituents of the solution. Certain of these, 
such as the nitrate and the chlorin, move through the soil very readily, 
while the sulphate and the carbonate are more sluggish. 
In the leaching experiment just described the soil solution was at 
first highly concentrated, and this concentration declined very rapidly 
with each successive fraction of the percolate. The conditions of that 
experiment differed from conditions that ordinarily exist in the field 
in that when the leaching began the soil in the tube was entirely dry. 
In an irrigated field the moisture content of the surface inch or two may 
be low, but below that one finds moist soil. The application of water 
to the top of a column of dry soil brings into solution at once a large 
part of the soluble material contained in the upper part of the column. 
As the resulting solution moves downward it continues to take up more 
soluble material until it reaches the bottom of the column and emerges 
as percolate. Each successive fraction of the descending column of water 
would come in contact with soil from which a large part of the soluble 
material had been removed, and the concentration of each succeeding 
fraction would be correspondingly reduced. 
The conditions of this leaching experiment also differed from conditions 
in the field in that the soil in the tube had been thoroughly mixed when 
