656 
Journal of Agricultural Research voi. xxvn, no. 9 
The conditions that obtain in the field where a saline soil is being re¬ 
claimed by leaching may be approximated most closely in the laboratory 
by using a glass pot, such as is shown in figure 4, or a glass tube partially 
filled with soil to which distilled water is added at the top. The water 
percolates downward through the soil, dissolving the soluble material, 
and is replaced by subsequent additions of water. The soil solution thus 
replaced escapes below where it may be collected for analysis. 
Table XIX .—Effect of diluting the soil solution on the balance of its constituents , the total 
solids being expressed as percentage of the dry weight of the soil and the constituents as 
percentages of the total solids a 
Constituents as percentage of total solids. 
Extract No. 
Total 
solids. 
Organic 
matter. 
CO.?+ 
HCO* 
2 
cl. 
SO<. 
Total 
acids. 
1. 
0.493 
6*9 
9-4 
19. 2 
29*3 
57-9 
2. 
. 480 
7.0 
8. 8 ’ 
16. 4 
32. 6 
57-8 
3 . 
.420 
8. 1 
9. 1 
IS -4 
3 1 * 2 
55-7 
4 .. 
•356 
7.6 
10. 3 
i 5 - 7 
31.8 
57-8 
5 . 
• 3 12 
8.0 
10. 0 
1 5-2 
31*9 
56. 1 
6.. 
■ 274 
8.9 
10. 7 
14. 7 
3 i -4 
56. 8 
7 ... 
. 228 
10. 2 
n- 5 
15-4 
29.4 
5 6 -3 
8. 
. 216 
10. 2 
12. 0 
14. 2 
29. 8 
56. 0 
9 . 
• 179 
10. 6 
14. 0 
14. 2 
28. 4 
56.6 
10. 
.178 
11. 6 
14. 5 
13-8 
26. 7 
55 -o 
11. 
. 141 
17. 1 
14. 9 
13 - 1 
27. 0 
S 5 -o 
12. 
. 136 
14. 5 
16. 0 
11. 1 
24.9 
52. 0 
13 . 
. 119 
16.8 
17. 0 
12. 5 
22. 7 
52. 2 
14 .... 
. 108 
16. 4 
16. 0 
12. 2 
19 - 5 
47 - 7 
° Reported by J. F. Breazeale. 
This method of leaching soils is subject to the same difficulties in the 
laboratory as are met in the field. With certain soils the dilution of the 
soil solution is accompanied by a change in the physical character of the 
soil such that the rate of percolation is reduced to the vanishing point. 
With soils that show this reaction to a marked degree it is no more 
practicable to conduct leaching experiments in the laboratory than it is" 
to reclaim them in the field. 
It has been observed by a number of investigators that when the soil 
solution contains a fairly high proportion of calcium and magnesium it 
is possible to dilute the solution without causing the soil to become im¬ 
permeable. On the other hand, when the soil solution contains a very 
low proportion of calcium and magnesium and a high proportion of sodium 
and potassium the dilution of the soil solution is likely to result in making 
the soil nearly or quite impermeable to water. 
It has been shown that this condition of potential impermeability may 
be induced in a soil that is naturally permeable by the application of even 
small quantities of sodium salts. Cummins and Kelley (6) cite a case 
where the application of sodium nitrate as a fertilizer to the soil of the 
Citrus Experiment Station at Riverside, Calif., has resulted in making 
the soil become relatively impermeable to water. 
