724 
Journal of Agricultural Research 
Vol. XXVIII, No. 8 
weed and the other by an equally good growth of pickle weed. The analyses of 
the salts of the arrowweed soil showed that over 63 per cent of the total salts 
were sulphates (sample 9, Table I) while the pickleweed soil showed a small 
amount of sulphates but over 57 per cent of the total salts as chloride (sample 
13, Table I). In another place where arrowweed was dying but saltgrass was 
thriving the fourth foot showed in the analyses (sample 8, Table I) over 26 per 
cent of the total salts to be bicarbonates and 6 per cent carbonates. 
GILA VALLEY 
PHYSIOGRAPHY 
The part of Arizona studied lies between Chandler and the Gila River (fig. 1) 
and between Florence, Casa Grande, Maricopa, and the Gila River. Detailed 
studies were made at Casa Grande in the fall and at Chandler both in spring and 
in fall. The whole of this area is a broad valley plain that slopes gradually upward 
toward the east and south. On the west there is an abrupt upward slope toward 
the Salt River Mountains. 
The center of the valley has been filled in to a great depth, leaving only the 
tops of the mountains rising above the valley floor. The material for this exten¬ 
sive filling was washed down from the Salt River mountains and others higher up 
on the drainage course. 
SOILS 
The soils of this area vary from the stony, partially disintegrated soils that lie 
at the bases of the mountains to the fine heavy soils, the “adobe,” of the center of 
the valley. This change is usually gradual until the lower parts of the valley are 
reached, where there is often an abrupt change from the sandier types to the 
heavy clay loam. The nitrogen and humus content of practically all of the soils 
of the valley is low. 7 
Table I .—Chemical composition of the salts of Coachella Valley soils , 1914 
and 1915 a 
[C rusts and surface soils were taken unless otherwise indicated. Results given in parts per 100,000 dry soil.] 
Sam¬ 
ple 
No. 
Plant growth 
Car¬ 
bon¬ 
ates 
Bi- 
car- 
bon- 
ates 
Chlo- 
rids 
Sul¬ 
phates 
Cal¬ 
cium 
Mag¬ 
ne¬ 
sium 
So¬ 
dium 
Po¬ 
tas¬ 
sium 
Total 
al¬ 
kali 
1 
3 
Cotton field,_ 
395 
10,990 
3,935 
1 2,980 
23,550 
2,430 
12,700 
26 
13,580 
36,300 
13.500 
422 
Trace. 
13,380 
Trace. 
38.700 
60,600 
28,100 
51,300 
22.700 
31,900 
300 
Cotton field _ 
618 
963 
Trace. 
18,800 
9,460 
18,720 
7,580 
11,800 
80 
Trace. 
4 
Washingtonia (palms)_ 
1,065 
Trace. 
717 i 
149 
379 
Trace- 
Trace 
5 
Allenrolfea (pickleweed),.... 
8,210 
11,820 
7,100 
85 
668 
Trace. 
Trace. 
6 
7 
Dondia (seepweed) Isocoma_ 
Dondia (seepweed)_ 
247 
545 
233 
76 
79 
38 
Trace. 
Trace. 
Trace. 
Trace. 
8 
Pluchea (arrowweed) dying, 
Distichlis (saltgrass), (fourth 
foot)_ 
17 
17 
Trace. 
Trace. 
9 
Pluchea (arrowweed)_ 
160 
564 
10,830 
208 
239 
Trace. 
5,320 
127 
Trace. 
17,100 
600 
10 
Bare spot in field, crust_ 
96 
103 
67 
Trace. 
Trace- 
11 
Bare spot in field, upper 6 inches. 
Date orchard_ 
130 
32 
114 
8 
Trace. 
116 
Trace. 
400 
12 
163 
6,910 
4,430 
224 
11,270 
374 
367 
169 
9,260 
1,645 
468 
Trace. 
28,200 
7,800 
2,000 
21,800 
69,070 
13 
Allenrolfea (pickleweed)_ 
164 
1,060 
178 
172 
Trace. 
14 
Mesquite (young tree)_ 
160 
974 
Trace. 
Trace. 
15 
Bare spot in Pluchea (arrow- 
weed) and Atriplex (saltbush). 
Dondia (seepweed), crust_ 
229 
8,380 
20,220 
1,790 
3,340 
5,450 
23,690 
3,410 
37,760 
6,100 
286 
392 
6,725 
24,170; 
2,054 
26,865 
Trace 
16 
Trace. 
140 
Trace. 
107 
17 
Dondia (seepweed), depth 1 foot. 
Pluchea (arrowweed), Atriplex 
(saltbush), crust_ 
54 
620 
Trace. 
84 
8,000 
82,210 
18 
5,030 
7,940 
30 
40 
248 
a Analyses made by the Bureau of Soils, United States Department of Agriculture. 
7 Means, T. H. soil survey in salt river valley, Arizona. U. S. Dept. Agr. Bur. Soils, Rpt. 
Field Oper. 1900: 287-332, illus. 1900. 
