770 
Journal of Agricultural Research 
Vol. XXVIII, No. 8 
ARROWWEED AND SALTBUSH COMMUNITY 
TOPOGRAPHICAL RELATIONS 
This community is unimportant outside of Coachella Valley. It is confined 
to “seep” areas or subirrigated strips of land along the rivers. The areas in 
Coachella Valley occupied by the mixture of arrow weed and saltbush occur 
almost entirely below a line drawn east and west through Thermal (fig. 2). 
Above this there are only narrow strips along the dry creeks. The areas are very 
irregular in form and are disconnected, usually skirting the pickle weed area and 
coming just within that covered by seepweed. 
Table XXII.— A comparison of spring and fall soil conditions at the same stations 
in typical areas of chamiso “sandbarsChandler , Ariz.j 1915 a 
Date of collection 
Date of collection 
Item 
Depth 
of 
soil 
Mar. 
16 
sample 
No. 2 
Mar. 
25 
sample 
No. 13 
Mar. 
25 
sample 
No. 18 
Mar. 
26, 
sample 
No. 20 
Aver¬ 
age 
Oct 1, 
sample 
No. 2 
Oct. 1, 
sample 
No. 13 
Oct. 1, 
sample 
No. 18 
Oct. 7, 
sample 
No. 20 
Aver¬ 
age 
Moisture equivalent... 
Feet 
1 
6.4 
6.4 
6.4 
5.5 
6.2 
6.4 
9.4 
7.0 
6.0 
7.2 
2 
7.9 
8.6 
6.7 
6.4 
7.4 
8.2 
9.8 
7.8 
6.7 
8.1 
3 
16.7 
10.0 
6.8 
6.7 
9.8 
15.2 
12.5 
7.4 
7.4 
10.5 
4 
14.8 
14.0 
6.0 
6.4 
10.3 
20.2 
13.7 
7.6 
7.9 
12.4 
Wilting coefficient_ 
1 
3.5 
3.5 
3.5 
3.0 
3.4 
3.5 
5.1 
3.8 
3.2 
3.9 
2 
4.3 
4.7 
3.6 
3.5 
4.0 
4.5 
5.3 
4.2 
3.6 
4.4 
3 
8.5 
5.4 
3.7 
3.6 
5.3 
8.3 
6.8 
+ 0 
4.0 
5.8 
4 
8.0 
7.6 
3.3 
3.5 
5.6 
11.0 
7.4 
4.1 
4.3 
6.7 
Moisture content 
1 
+2.0 
+ 1.7 
-0.2 
+1.4 
+ 1.2 
-2.7 
-4.2 
-2.8 
-2.8 
-3.1 
above or below wilt- 
2 
+3.6 
+3.7 
+ 1.8 
+3.5 
+3.2 
-2.0 
0.0 
-1.6 
-1.3 
-1.3 
ing coefficient. 
3 
+5.3 
+5.9 
+2.6 
+ 2.0 
+4.0 
-1.5 
+2.3 
-1.1 
-1.0 
-0.3 
4 
+5.6 
+4.9 
+3.2 
+3.7 
+4.4 
-1.1 
+2.8 
-0.5 
-0.8 
+0.1 
Salt content......._ 
1 
.01 
.06 
.01 
.01 
.02 
.02 
.02 
.01 
.01 
.02 
2 
.01 
.02 
.01 
.01 
.01 
.02 
.40 
.01 
.01 
.11 
3 
.02 
.11 
.01 
.02 
.04 
.02 
.38 
.01 
.01 
.11 
4 
.02 
.61 
.01 
.01 
.16 
.02 
.50 
.07 
.01 
.15 
<* All data in this table are stated in percentages of the dry weight of the soil. 
BOTANICAL COMPOSITION 
While the arrowweed ( Pluchea sericea (Nutt.) Coville) (PL 12, B) and the 
saltbush ( Atriplex lentiformis (Torr.) S. Wats.) (PI. 12, A) also occur separately 
as pure types, the areas of each are very small. 
In Coachella Valley the two are nearly always intermingled, often with addi¬ 
tional plants of Isocoma veneta acradenia (Greene) H. M. Hall, Dondia torreyana 
(S. Wats.) Standi, and Prosopis glandulosa Torr. Here, as in the case of the seep¬ 
weed area, the salt crust on the surface of the soil excludes all annuals. In the 
Gila Valley, shrubs found mixed with the arrowweed and saltbush are Dondia 
intermedia (S. Wats.) Heller, Isocoma wrightii (A. Gray) Rydb. and Atriplex 
canescens (Pursh) Nutt. Here, as in Coachella Valley, no annuals were found. 
APPEARANCE 
This type of vegetation shows a very rank, dense, shrubby growth, often 6 
feet high or higher. In favorable places the shrubbery is so thick as to be scarcely 
penetrable; more often, however, there are open spaces of several feet between 
the plants, which are usually covered with a heavy alkaline crust (PI. 12, A) 
9 PHYSICAL CONDITIONS INDICATED 
Soil Moisture 
The land occupied by the arrowweed and saltbush type of vegetation in 
Coachella Valley is characterized by the same soil texture as that of the pickle- 
weed land. The first 2 feet are of considerably finer texture than the third and 
fourth (Table XXIV). The soil moisture is influenced to a large extent by 
the high-water table, so that there is an available water supply all the year 
round below the surface foot (Tables XXIII and XXIV). In spring, the 
water comes almost to the surface of the soil, although not as high as in the 
pickle weed land. 
