Investigations Begarding Brack" {Alkali) in Cape Colony Soils. 145 
The land most affected by alkaline salts is that in the immediate 
proximity of the dam, and from there the saline area is working its way 
downwards by degrees, the lands being drenched with water during the 
season, and then left to the action of evaporation, which does not fail to 
draw the salts to the sm-face, with the consequence that, in the long run, 
one area after another has been discarded as too salt for cultivation. 
Under such circumstances, the practice has been to transfer to a plot of 
virgin soil until that, in turn, becomes too alkaline for use. 
To test chemically the results that this mode of cultivation brings 
about, samples of soil, T and V, were taken, respectively, from Lot 111, 
which had been under cultivation for seventeen years, and had, during 
that period, grown fourteen crops of wheat, and from Lot 94, which had 
never been cultivated, at a spot 315 yards from that where T was collected. 
The crops at T were originally as good as could be desired, but have been 
gradually deteriorating. The sample taken at V is typical of the Van Wyks 
Vlei soil in its natural state. 
The way in which these samples were collected was as follows : In 
each case an excavation was made to a depth of 7 feet, and, down one side 
of the excavation, a vertical groove, of 6 inches square section, was cut by 
removing for analysis blocks of soil of 6 inches cube at 6-inch intervals. 
The first sample of each series was taken from the surface to a depth of 
6 inches, and then samples of each alternate 6 inches below that. In both 
cases, at a depth of 6 feet, a stratum consisting for the most part of large- 
sized stones was encountered ; of this it was not considered necessary to 
make analyses, but the soils taken from the higher levels were examined 
for alkaline salts, with the results tabulated below : — 
VAN WYKS VLEI (CAENAEVON DIVISION) SOILS. 
Number. 
Sodium 
Chloride. 
Sodium 
Sulphate. 
Total Alkaline 
Salts. 
Calcium 
Chloride. 
Calcium 
Sulphate. 
Calcium 
Carbonate. 
Mangesium 
Chloride. 
Magnesium 
Sulphate. 
Magnesium 
Carbonate. 
Total S 
Sal 
O 
31 
)oluble 
ts. 
o 
Tl 
% 
% 
% 
% 
% 
% 
% 
% 
% 
% 
% 
•849 
•849 
1^542 
•106 
•014 
■046 
2-557 
2-672 
T2 
•432 
•432 
•114 
•040 
•022 
•029 
•637 
•708 
T3 
•355 
•355 
•039 
•081 
•024 
•017 
•516 
•548 
T4 
•359 
•105 
•464 
•003 
•038 
•036 
•541 
•594 
T5 
•304 
•363 
•667 
■049 
•034 
•065 
•816 
•840 
T6 
•214 
•397 
•611 
•037 
•007 
•Oil 
•666 
•664 
VI 
•051 
•051 
•068 
•019 
•024 
•012 
•174 
•222 
V2 
•355 
•355 
•500 
•032 
•026 
•090 
1-003 
1^056 
V3 
•590 
•590 
•404 
•071 
•020 
•066 
1-151 
1-210 
V4 
•736 
•736 
•082 
•198 
•026 
•055 
1-097 
1-102 
V5 
•759 
•318 
1^077 
•042 
048 
■007 
•053 
1 -227 
1-238 
V6 
•502 
•419 
•921 
•105 
•017 
•006 
■049 
1-098 
1^116 
10 
