930 
Journal of Agricultural Research vd. xxm. No.» 
Table III .—Daily precipitation, in inches, Sacaton t Ariz., from March to October, in¬ 
clusive, 1Q20 
Mar. 
1.. 
10.. 
23-• 
24.. 
25.- 
27.. 
Apr. 
15.. 
19.. 
May 
21.., 
June 
26.., 
27.., 
Trace. 
0.47 
.07 
^ ' 53 
Trace. 
„ *34 
Trace. 
•03 
• 17 
• 13 
. 10 
July 
13.... 
21... 
22... 
Aug. 
2... 
10... 
14.... 
19.... 
25.... 
Sept. 
3... 
14.... 
Oct. 
20.... 
3 1 • * • • 
35 
11 
02 
28 
09 . 
01 
24 
27 
3 
86 
35 
ARRANGEMENT, PLANTING, AND THINNING 
The soil of the experimental plot is a black sandy loam, very well 
suited to the growing of cotton. Clear well water is used for irrigation, 
which is distributed from a concrete ditch provided with leak-proof gates. 
Nine sixth-acre borders 6 were used for the experiment, arranged in series 
of three borders each. The first series, containing borders C1-3, C1-4, 
and C1-5, had been in alfalfa the previous year. The other two series, 
covering borders C1-9 to Ci-14, inclusive, and forming a solid block, 
had grown cotton in the previous season. The soil of series I is slightly 
richer than that of the others. 
The experiment was planted on March 29 and April 1 with a 2-row 
planter, using a 44-inch row spacing, and a good stand was obtained. 
Unfavorable low temperatures through April and early May kept the 
ground cold and retarded the growth of the young seedlings. During 
this cold period injuries from the “ sore-shin ” disease were not uncommon 
in the Salt River Valley, while at Sacaton, with lower temperatures pre¬ 
vailing, the damage from this source was considerably greater, but the 
stand was materially affected only in a few cases. 
Series I was thinned on June 4, when the cotton was about 12 inches 
high, Teaving the plants as nearly as possible a foot apart in the row. 
The plants in this series were in a slightly more advanced stage of develop¬ 
ment than those of the other two series. Series II and III were thinned 
on June 14, when the plants had reached the same stage of development 
as had been attained in series I, and with the same row spacing. 
PLAN OF IRRIGATION 
The irrigation treatments that were applied to the three borders in 
each series were recorded as “normal,” “medium-heavy," and “heavy,” 
respectively. An explanation of these terms is necessary in the absence 
of any such definite or recognized practices. 
“ Normal” irrigation was the application of water in such a manner as 
to keep the plants flowering heavily and with little or no wilting of the 
leaves in the middle of the day. This is considered the best cultural 
practice in the Salt River Valley. 7 
“Heavy” irrigation was to apply water at definite intervals regardless 
of the condition of the plants or soil. As near as possible a 10-day period 
* Border is a term applied to a portion of a field used as an irrigation unit. 
7 Hudson, E. W. growing Egyptian cotton in the salt river valley, Arizona. U. S. Dept. 
Agr. Fanners* Bui. 577, 8 p. 1914. 
