638 
Journal of Agricultural Research 
Vol. XXVII, No: 9 
Table X .—Salt content of the soil solutions obtained by displacement from four samples 
of soil 
Sample No. 
Percentage 
of solution 
to soil. 
Salt content 
of solution. 
Indicated 
salt content 
of soil. 
384. 
r - 
Per cent. 
• o- 595 
. o?o 
Per cent . 
O. T 2 7 
385. 
0 J 
47 
. 028 
. OIZ 
386. 
47 
• '■'oy 
. 070 
385a . 
46 
1. 510 
. 694 
The samples of the soil solution obtained either by the centrifuge or 
by displacement may be considered as representing a condition when 
the soil contains an ample supply of water for plant growth. A number 
of investigators have proposed methods of obtaining samples of the 
soil solution when the moisture content is at or just below what is con¬ 
sidered as optimum for plant growth, but none of these methods has as 
yet come into general use in work with irrigated soils. 7 
In view of the fact that most of the investigational work concerning the 
salt content of soil is based on results obtained by treating the soil sample 
with quantities of water that supersaturate it, similar treatments were 
made on portions of the same samples that were used in the experiments 
just described. 
In each extraction ioo gm. of soil were used. For one set this soil 
was treated with ioo cc. of water, for the next 250 cc. of water, for the 
third 500 cc. of water, and for the fourth 1 litre of water. The wetted 
samples were held for 24 hours and were shaken repeatedly. A part of the 
water was then filtered off and tested for total salts. The results of these 
tests together with those made on the centrifuge and displacement 
extracts are shown in Table XI. 
Table XI .—Salt content of the solution and the indicated salt content of the soil when 
the soil solution was variously diluted 
Sample No. 
Percentage 
of solution 
to soil. 
Salt content 
of solution. 
Indicated 
salt content 
of soil. 
Per cent . 
Per cent. 
33 
I. 020 
0. 337 
55 
• 595 
•327 
384. 
IOO 
. 287 
. 287 
250 
. 127 
.318 
5 °° 
. 065 
•325 
1,000 
.030 
.300 
36 
• 050 
. 018 
47 
•059 
. 028 
.« 
IOO 
.038 
.038 
250 
. 016 
. 040 
500 
. on 
•055 
1,000 
. 007 
. 070 
1 The following papers are among the more recent contributions to the subject of extracting the soil solu¬ 
tion and each contains citations of earlier work. 
Parker, F. W.: methods op studying the concentration and composition op the sou, solution 
{14). Burgess, Paul S.: the soil solution, extracted by Lipman’s direct pressure method, com¬ 
pared with 1:5 water extracts (5). Burd, John S., and Martin, J. C.: water displacement op 
soils and the soil solution (4). Tulaikov, N. M., and Kusmin, M. S. : ON the question op obtain¬ 
ing THE SOIL SOLUTION ( 10 ). 
