i 
BULLETIN 1175, U. S. DEPARTMENT OF AGRICULTURE. 
Table 5. — Monthly, seasonal, ani8-year monthly average precipitation and evaporation' 
tit the Woodward Fid'/ station, during the growing season (April to September), during 
the 8-year period from 1914 to 1921, inclusive. 
[Data (in inches) furnished hy the Office of Biophysical Inves 
tigations, B 
ureau 
of Plant Industry.] 
Apr. May. 
June. 
July. 
Aug. 
Sept. 
Total. 
Year. 
poration. 
ipitation. 
A 
o 
3 
| 
i 
S3 
3 
ft 
o 
ft 
a 
a 
2 
o 
ft 
c 
_© 
"ft 
| 
"S 
o 
ft 
| 
03 
j 
o 
H 
o 
t I 
03 
> 
i 
03 
> 
1 
- 
> 
£ 
c3 
> 
<B 
s 
> 
2 
g 
"3 
- 
fH Hn 
w 
fc 
w 
- 
- 
* 
H 
ft 
H 
8. 1 
- 
W 
~ 
1914 
1.7 
6. S 3. 2 
6.2 
0.6 
11.3 
1.9 
10.9 
2.6 
I. 
0.6 
10.6 
52.5 
4.94 
1915 
6.5 
6. 5. 3 
6.7 
2.4 
6.6 
3.1 
10. 
3.6 
6.5- 
5.7 
5.8 
26.6 
41.6 
1.56 
1916 
1.8 
5. 9 1. 7 
10.1 
10.3 
8.2 

10.7 
1.0 
11.1 
2.3 
7.9 
17.1 
53.9 
3.15 
1917 
1.6 
6.8 1.0 
7.0 
1.4 
11.5 
1.1 
11.7 
6.7 
7.6 
2.7 
5.3 
14.5 
49.9 
3.44 
litis 
2.2 
5. 4. 
9.3 
1.9 
8.7 
. 7 
10.1 
1.4 
11.0 
1.2 
5.8 
11.4 
49.9 
4.38 
1919 
4.1 
6. 4. 3 
5.4 
2.2 
6.4 
1.4 
10.7 
1.9 
9.3 
.6 
7.6 
14.5 
45.4 
3. 13 
1920 
1.1 
7. 7 3. 4 
6. 4 
1.3 
ID. 4 
4.7 
9.8 
3.0 
6.9 
5.0 
7.3 
IS. 5 
48.5 
2.62 
1921 
1.8 
6.9 1.9 
8.0 
5.8 
7.3 
2.5 
9.3 
5.1 
10.3 
2.9 
8.8 
20.0 
50.6 
2.53 
Average 
2.6 
6. 4 3. 1 
7.4 
3.2 
8.8 
1. 9 10. 4 
3.2 
9.0 
2.6 
7.1 
16.6 
49.0 
2.95 
Table 5 shows a comparison of the monthly precipitation and 
evaporation as recorded at the Woodward Field Station during the 
sixjnonths from April to September, inclusive, for each year of the 
8-year period from 1914 to 1921, inclusive. The evaporation meas- 
ured is from a free water surface, the method being that employed 
by the Office of Biophysical Investigations of the Bureau of Plant 
Industry. During this period the evaporation has been about three 
times as great as the precipitation. July has the highest average 
evaporation and the lowest precipitation of the months considered 
in this 8-year period, the evaporation having been more than five 
times as great as the precipitation for this month. The average 
evaporation and precipitation for June and August are practically 
the same for this period. 
CLASSIFICATION OF THE GRAIN SORGHUMS. 2 
The grain sorghums consist of several distinct groups of varieties, 
together with varieties which have doubtless originated by hybridiza- 
tion and are difficult to class definitely with any of the recognized 
groups. The different groups and varieties react differently to 
environmental conditions and naturally give different results under 
the varying climatic conditions of the southern Great Plains. To 
understand the results of the experiments reported herein, it is 
necessary to know the characters by which the groups and varieties 
differ. The relation of grain sorghums to other sorghums is first 
shown and a key to the groups of grain sorghums is then presented, 
indicating the characters by which the groups are distinguished. 
The sorghums grown in this country may be divided into four 
general agronomic divisions, as follows: 
(1) Grain sorghums, sorghums grown primarily for the feeding value of the grain, 
including such groups as kaQr. durra and milo. and kaoliang. 
(2) Sorgos, or forage sorghums, known also as sweet or saccharine sorghums, includ- 
ing such varieties as Amber. Orange, and Sumac. 
> (3) Broom corn, a specialized sorghum grown for the threshed panicle utilized for 
brooms. 
I rrass sorghums, which include Johnson, Sudan, and Tunis grasses. 
- Classification from Ball, C. R.. and Rothgeb, B. E. Grain-sorghum experiments in the Panhandle of 
Texas O. S. Dept. Agr. Bul.698 91 p., 13 fig. ' L918. 
