366 
Journal of Agricultural Research 
Vol. I, No. 5 
After a reconnoissance trip through portions of Wyoming, Utah, 
Idaho, and Oregon in August, 1911, the Tooele Valley in central Utah 
was selected for the following reasons: (1) several very distinct types of 
vegetation are found within a small area, (2) the soils show a great 
diversity in their moisture conditions and salt content, (3) the greater 
part of the area retains its original plant cover, while examples of crop 
production both with and without irrigation exist on different types 
of land. 
Detailed studies of the vegetation of Tooele Valley in relation to the 
moisture conditions and salt content of the soil were carried on in 1912. 
The work was begun near the close of the rainy season (end of May) 
and was terminated during the first week of August, when the summer 
drought had reached its height. Additional data were obtained during 
a third visit to the valley in the latter part of August, 1913. 
The distribution of the native vegetation was found to depend in a 
marked degree upon the physical and chemical properties of the soils, 
factors which also influence crop production. So far as this particular 
area is concerned, the vegetation can unquestionably be used with 
advantage in classifying land with respect to its agricultural value. 
To what extent the correlations established in Tooele Valley hold good 
in other parts of the Great Basin region remains to be determined by 
future investigation. 
The writers desire to acknowledge the helpful cooperation of Director 
E. D, Ball, of the Utah Agricultural Experiment Station, and of Prof. 
L. A. Merrill, formerly of that station. The writers are indebted for 
the determination of the plants collected to Mr. Ivar Tidestrom, of the 
Office of Economic and Systematic Botany, Bureau of Plant Industry. 
METHODS OF RESEARCH 
The methods used in classifying and describing the types of vegetation 
are well known to ecological plant geographers and are best described in 
setting forth the results. Some explanation of the methods used in 
investigating the moisture conditions and salinity of the soils, however, 
is desirable. 
Samples of the soil were taken in the midst of the areas occupied by 
each vegetation type. Where the boundaries between two types were 
well defined, samples were also taken on both sides of the line, in order 
to determine the limiting conditions for each type. The measurements 
of moisture content, moisture equivalent, electrical resistance, and salt 
content which were made upon these samples served as a basis for con¬ 
clusions regarding the physical conditions indicated by the presence of 
each important type of vegetation. 
Coelecting Soil Samples. —The samples of soil were in all cases 
collected with the aid of a sampling tube, which prevents the admix¬ 
ture of surface material with the subsoil. Each sample consisted of a 
