Investigations Begarding ''Brack'' (Alkali) in Cape Colony Soils. 137 
studded with gaps. These drawbacks, however, do not prevent certain 
definite deductions. It is noticeable that, as a rule, the amounts of sodium 
chloride, and of soluble salts generally, steadily increase as we proceed 
downward from the surface to the 6-foot limit, and that this downward 
limit increase becomes more rapid as we pass from A towards E. 
Taking the entire 6-feet depth of soil, in each case the average per- 
centages of salts, as far as they may be based on the foregoing deter- 
minations, are as follows : — 
Total Soluble Salts. Sodium Chloride. 
A — -0521 
B — -0421 
C -189 -0100 
D -530 -1373 
E -966 -3348 
The question now to be pronounced on is : What would be the effect 
of irrigation upon such soils ? Broadly speaking, and having no regard 
to modifying causes, there can be only one answer. The result of 
irrigation would assuredly be to raise the bulk of the alkali salts, within 
the first 4 feet of soil, to the surface. 
It appears most probable that the low rainfall in the district around 
Houw Water, accompanied by other causes, prevents the water from ever 
penetrating the soil to any great extent, and, therefore, from bringing up 
the salts during subsequent evaporation. Irrigation would very probably 
alter all this. The large quantity of water led on to the soil is bound to 
penetrate, and, when evaporation follows, as it undoubtedly must, large 
quantities of salt will be carried up to the surface, and accordingly render 
the surface soil more saline. 
In connection with some alkaline soils it has been found at Tulare, in 
California, that, although the salts in the soil have been drawn upwards, 
they have not been drawn right to the surface, and, in spite of the fact 
that a considerable amount of alkaline salts was present in the soil, there 
was not sufficient at the surface to cause any interference with the growth 
of shallow-rooted crops like barley, which flourished, to all appearances, 
satisfactorily. The reason for this is to be found in the fact that the 
surface soil was kept under constant cultivation, whereby evaporation 
from the soil itself was checked, and proceeded instead from the verdure 
of the cultivated crops. If the land can be kept under continuous culti- 
vation, there would be simultaneously two causes at work to retard 
evaporation, and consequently prevent the rise of alkaline salts to the 
surface. Evaporation from foliage instead of from soil would not be 
the only saving factor, but the shading of the ground by the crops reducing 
its temperature, still further diminishes the tendency to evaporation from 
the soil surface. 
