May 24,1924 
Significance of the Southwestern Desert Vegetation 
755 
Salinity 
The salt content of desert-sage land is shown in Tables X, XI, and XII. All 
of the 4 feet of soil show appreciable quantities of salt, and vary considerably. 
This is more easily understood if the fact is considered that pure areas of desert- 
sage may be either of a good growth, 3 to 4 feet high, or poor scrubby growth, I 
to 2 feet high. Samples taken in these two extremes of the plant growth in 
Coachella Valley show considerable difference in the salt content (Table XIV). 
A typical desert-sage area of a good growth indicates land having a negligible 
amount of salt. The average amount of salt of all the samples in the desert- 
sage is much higher than a Similar average of the creosote bush samples (Table 
XXXIV). The abrupt changes in the salinity as well as the texture and mois¬ 
ture of the soil follow closely the abrupt changes of the elevation and slope of 
the land covered by these two associations. 
The desert-sage in the Gila Valley indicates a lower salt content in the first 
two feet of soil than in the Coachella Valley. With the exception of the first 
foot, the salt content is four times as great as in the creosote bush land. On the 
whole, a typical area of desert-sage indicates land that is not too saline for farm¬ 
ing purposes. The salt content of the soil varies with the growth and conditions 
of the plants forming the area. If, as in the case of the Coachella Valley data 
the data in Table XII is separated into three groups, according to the field notes 
on the growth and conditions of the plants, whether poor, medium, or good 
(Table XIII) it will be seen that the salt content is much less in the good group 
while it rises considerably, especially in the third and fourth feet, in the poor 
group. 
The salt content is lower in desert-sage land in the Gila Valley, somewhat 
higher in the Coachella Valley, and negligible around Casa Grande where it has 
approximately the same salt content as the creosote bush land of the Gila Valley. 
Summary of Physical Conditions 
The desert-sage indicates land of a much finer texture and greater moisture¬ 
holding capacity than the creosote bush land. The penetration of the water, 
however, is much less on the desert-sage land, due to the heavier soil and layer 
of silt so often deposited on the surface as a result of flood water following the 
winter rains. A good growth of desert-sage in the Gila Valley indicates land that 
has a soil texture ranging from a sandy to a fine sandy loam, and somewhat 
coarser than that indicated by the same plant in the Coachella Valley. There is 
available moisture to a depth of 4 feet in spring, but none in the fall. The amount 
of available water is therefore much less than on the creosote bush land. The salt 
content is much higher in the desert-sage land though, wherever there is a good 
growth of desert sage, the salt content of the soil is negligible. Where the growth 
is poor the salt content is greater, but never excessive. 
