772 
Journal of Agricultural Research 
Vol. XXVIII, No g 
Table XXIV.— Comparison of the spring and fall soil conditions at the same 
stations in typical areas of saltbush and arrowweed , Indio , Calif., 1915 a 
Date of collection 
Date of collection 
Item 
Depth 
of soil 
Mar. 4, 
sample 
No. 31 
Mar. 4, 
sample 
No. 32 
Mar. 5, 
sample 
No. 33 
Aver¬ 
age 
Sept.23, 
sample 
No. 31 
Sept.23, 
sample 
No. 32 
Sept.23, 
sample 
No. 33 
Aver¬ 
age 
Moisture equivalent. 
Feet 
1 
22.5 
32.9 
29.5 
28.3 
24.5 
32.4 
26.5 
27.8 
2 
10.0 
23.6 
25.3 
19.6 
22.2 
19.0 
24.0 
21.7 
3 
4.1 
20.0 
23.9 
16.0 
14.0 
20.8 
24. 7 
19.8 
4 
4.7 
13.2 
23.0 
13.6 
25.2 
11.8 
19.3 
18.8 
Wilting coefficient. 
1 
12.2 
17.8 
16.0 
15.3 
13.3 
17.6 
14.4 
15.1 
2 
5.4 
12.8 
13.8 
10.7 
12.1 
10.4 
13.1 
11.9 
3 
2.2 
10.9 
13.0 
8.7 
7.6 
11.3 
13.4 
10.8 
4 
2.6 
7.2 
12.5 
7.4 
13.7 
6.4 
10.5 
10.2 
Moisture content above or 
1 
+9.4 
+13.3 
+19.7 
+14.1 
+1.9 
-8.6 
+6.7 
0.0 
below wilting coefficient. 
2 
+8.5 
+13.2 
+15.8 
+12.5 
+7.1 
-2.2 
+7.5 
+4.1 
3 
+4.7 
+13.2 
+18.1 
+12.0 
+5.9 
-3.8 
+10.2 
+4.1 
4 
+8.1 
+18.9 
+22.2 
+16.4 
+8.4 
-1.9 
+18.4 
+8.3 
Salt content. 
1 
>2.50 
>2.50 
>2.50 
>2.50 
>2. 50 
1. 72 
2.18 
2.13 
2 
1.06 
.32 
.50 
.63 
2.50 
1.04 
.52 
1.35 
3 
0.32 
.16 
.35 
.28 
1.10 
.19 
.20 
.50 
4 
0.28 
.15 
.16 
.20 
1.18 
.16 
.14 
.49 
a All data in this table are stated in percentage of the dry weight of the soil. 
Both of the plants develop in the summer and have dense foliage during the 
driest part of the year. In November most of the leaves are dead. The plants 
emain in this dormant condition until warm weather the next season. 
Arrowweed and saltbush land, when cultivated for a time and then abandoned, 
soon reverts to the same type of vegetation without an intermediate stage. If 
this land is cleared, irrigated, and planted, bare spots eventually appear in the 
fields. These are due partly to a rise in the water table and partly to an 
increase in the salt content of the surface soil. To insure permanent culti¬ 
vation, it is necessary to supply drainage. 
VARIATIONS FROM THE TYPICAL ASSOCIATION 
Saltbush 
In the Gila Valley the arrowweed and saltbush gives way to either areas where 
saltbush predominates or areas of pure saltbush, in which case the plants are 
large, luxuriant, and widely spaced (PI. 12, A). These areas (fig. 3) are even 
less extensive than in Coachella Valley. They occupy similar situations—that 
is, the moister irregular areas along rivers or the abandoned fields where the 
water table is high. The texture of the soil is more like that of the mesquite 
thicket, having a higher moisture equivalent than that of any of the other types. 
As regards soil moisture, this land is wetter than mesquite thicket land since, at 
least in spring, the ground is wet to the surface and apt to be boggy. Even in 
October there is an abundance of water, in all 4 feet (Table XXV). 
The physical conditions of land characterized by saltbush are (1) a soil that 
is uniform, at least 4 feet deep, and of fine texture; (2) a high water table; (3) 
an average salt content of % per cent for the first foot, while the average for 
all 4 feet ranges from % to M P er cent. 
