184 
Journal of Agricultural Research 
Vol. I, No. 3 
amount of bases of the soil (Ca, Mg, etc.) present in the resulting solution 
was found to be negligible. If, however, too great an excess of sodium 
hydroxid is present, the resulting solution is discolored, and iron in 
appreciable amounts is found in the solution. 
It was found that the addition of a small amount of sodium hydroxid 
to a solution of potassium chlorid prevented the presence of dissolved 
bases when the solution is shaken up in contact with a soil, and yet a loss 
of potassium occurred of the same magnitude as when bases were found 
in the resulting solution, the amount of chlorin remaining practically 
unchanged. 
Believing the assumption previously made to have been entirely justi¬ 
fied by the foregoing experimental work, the hope of finding the effect of 
concentration, size of soil particles, and presence of other substances, 
with special regard to substances commonly used in fertilizer practice, 
on the selective adsorption by soils led to the following experimental 
work: 
SERIES No. 3 
In series No. 3, 35-gram portions of a Norfolk sandy loam collected 
near Laurinburg, N. C., and a Marshall silt loam collected near Edgerton, 
Mo., were placed in 200 c. c. bottles with solutions of potassium chlorid 
containing varying quantities of potassium chlorid and a small amount 
of sodium hydroxid per liter. The bottles were then rotated in a ther¬ 
mostat at room temperature for two days. The soil was allowed to 
settle until the supernatant liquid was apparently clear. Portions of 
the supernatant liquid were then pipetted off, filtered, and analyzed, 
the results of the analyses being given in Table II. 
Table II .—Effect of concentration on adsorption of potassium from solutions of potas¬ 
sium chlorid by Norfolk sandy loam and by Marshall silt loam. 
Norfolk sandy loam. 
Marshall silt loam. 
Quantity of KC 1 equivalent 
to the quantity of K per 
100 c. c. of solution. 
Loss. 
Quantity of KCl equivalent 
to the quantity of K per 
100 c. c. of solution. 
Loss. 
Before contact. 
After contact. 
Per 100 
c. c. of 
solution. 
Percent¬ 
age. 
Before contact. 
After contact. 
Per 100 
c. c. of 
solution. 
Percent¬ 
age. 
Grams. 
25-855° 
14. 7700 
9. 1250 
6. 2580 
4. 7400 
3.1120 
1. 8380 
. 6406 
.3064 
. 1283 
Grams. 
25. 6750 
14. 6500 
8. 9650 
6.1100 
4 - 5950 
2.9600 
1. 7010 
. 5640 
.2650 
. 0960 
Grams. 
O . 1800 
. 1200 
. 1600 
. 1480 
• 1450 
. 152O 
. I370 
. 0766 
.0414 
*0323 
O. 70 
.81 
Im 75 
2.36 
3. 06 
4.89 
7 - 45 
11. 96 
I 3 * 5 i 
25. 18 j 
Grams. 
II. 8400 
IO. 0450 
6. 6950 
4. 4860 
2. 6700 
I. 1640 
Grams. 
II.3500 
9. 5700 
6, 2450 
4. 0420 
2. 24OO 
. 7700 
Grams. 
O . 4900 
•4750 
.4500 
.4440 
.4300 
.3940 
4. 14 
4 - 73 
6. 72 
9. 90 
16. 11 
33 - Si 
