The Soil. 
39 
sulfates, but tends to show that the silicic acid is present as easily 
soluble silicates, probably as an alkaline silicate. 
THE DISTRIBUTION OF THE SALTS IN THE FIRST AND SECOND TWO 
INCHES OF THE SOIL. 
§ 78. I regret exceedingly that these sets of samples were not 
taken on the same date, but the record shows them to have been 
taken nearly a year apart. The set representing the first two inches 
having been taken in June, 1899, and that representing the second 
two inches in May, 1900. The two series are not comparable, 
except in a very general way, but the members of the series are 
perfectly so among themselves. The larger features of their differ- 
snces are probably thoroughly representative of the facts, and show 
that the first two inches of the soil contains a somewhat higher per¬ 
centage of soluble salts than the second two inches; that the sodic 
and magnesic sulfates constitute a materially higher percentage of 
these salts than they do in the second two inches; that the first two 
yielded less silicic acid than the second two inches; that the potassic 
oxid soluble in water is very irregular, but is present in both series 
in significant quantities; that there is no soluble phosphorie acid in 
the series representing the first two inches, and is present through¬ 
out that representing the second two inches. I was at first inclined 
to think that this was an error, but it is not. The plots from which 
these samples were taken had been cultivated, but had not received 
any manure. 
§ 79. The uniformity of the presence of phosphoric acid as 
well as the significant quantity in which it is present is a matter of 
some surprise. Phosphoric acid is sometimes present in drainage 
waters in appreciable quantities, but usually only in traces. I have 
repeatedly tested the residues obtained by evaporating the ground 
waters of this plot for phosphoric acid, but I have not been able to 
prove the presence of a trace of it. 
In regard to the silicic acid, a trifling amount of it might have 
been derived from the glass by solution, aided by the repeated 
shaking of the mass in the bottles, but the solutions made quickly, 
using freshly distilled water, gave the same results. 
THE ALKALI. 
§ 80. The efflorescence which forms on the surface of the soil 
is popularly called alkali, and is of common occurrence in many 
places in all parts of the State. It is not my intention to go into 
this subject at present, except as it pertains to this particular soil. 
§ 81. There are small areas almost everywhere, especially in 
irrigated sections, which at times are white with a crop of these 
salts. They are not sightly from the agriculturists’ standpoint, but 
are much less injurious in themselves than the conditions which 
admit of their formation. We have seen that among the salts 
