BULLETIN 1200, U. 
DEPARTMENT OF AGRICULTURE. 
Table l.-~ Monthly, annual, and seasonal precipitation at the eight field station? 
where sorghum experiments were conducted for the years during which these exper- 
iments were in progress, with averages for this period and for the whole period 
covered by climatic data, together with seasonal evaporation comparisons — Contd. 
Year. 
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Dalhart, Tex.: 
1916 
.44 

.12 
1.49 
.69 4.11 
2.55 3.45 .72 
.22 
.03 .37 
14.19 
13.01 
3 
1917 
.14 
.09 
.03 
.37 
2. 70 . 93 
1.64 2.28 1.28 
.31 
1.02 
10.79 
9.20 57.40 
1918. 
.27 
.05 
2.85 
.89 
4. 87! 1-23 
1.49 1.67 1.49 
1.87 
.25 1.74 
18.67 
11.64 " 
1919 
.09 
.96 
3. is 
3.48 
2.75] 1.88 
2.41 
3.45 5.12 
2.50 
1.14 T 
26.96 
19.09 , 
1920 
.36 
.43 
.05 
.32 
3.25 6.81 
2. 56 
1. 33 . 81 
4.49 
.34 .08 
20. 83 
15. On 16. 24 
1921 
1.80 
.08 
.15 
.76 
3.70 
5.82 
5.12 
.69| .04 
.54 
I .26 
18.96 
16.13 44.47 
Average: 
! 
1916 to 1921 
.52 
.27 
1.06 
1.22 
2.99 
3.46 
2.63 
2.15 
1.58 
1.66 
.46 
.41 
18.40 
14.03 50.61 
1908 to 1921 
.26 
.39 
.63 
1.75 
2.94 
3.10 
2.58 
1.96 
1.25 
1.46 
.51 
.55 
17.38 
13.58, 
Big Spring, Tex.: 
1915 
.45 
.15 
.83 
5.75 
.44 
1.58 
3.43 
3. . 2.91 
1. 33 

.67 
20.84 
17.41 
1916 
.13 

1.74 
2.12 
.14 
1.59 
2.48 
4. 31 . 87 
1.30 
1.01 
.10 
15.79 
11.511 58. IS 
1917 
.28 

.03 
.97 
.61 
.98 
.73 
.17 .79 

.12 

4.68 
4.25 67.79 
1918 
.60 
.73 
.09 
.10 
1.19 
3.53 
.16 
.24 1.66 1.99 
.74 
1.32 12.35 
6. 88 . 
1919 
.57 
.06 
3.06 
1.45 
1.43 
8.28 
.95 
3.60 7.43 
6.31 
.78 
.09 
34.01 
23. 14| 50. S9 
1920 ..... 
1.97 
.20 
.12 
.08 
5.32 1.33 
.91 
6.30' .69 
1.95 
2.22 
.20 
21.29 
14.63 53.44 
1921 
.25 
.90 
1.15 
.11 
3.69 
2.77 
.45 
.85 .:: 
.23 
T 
T 
11.11 
8.58 
Average: 
1915 to 1921 
.61 
.-9 
1.00 
1.51 
1.83 
2.87 
1.30 
2.68 
2. If 
1.87 
.70 
.34 
17.15 
12.34 59.46 
1900 to 1921 
.42 
.60 
.79 
1.67 
2.48 
2.28 
2.14 
1.97 
2.12 
2.04 
1.19 
.61 
18.31 
12.66 
Tucumcari,N.Mex.: 
" l 
1914 
.30 
.40 
.50 
2.52 
5.24 
2.81 
3.90 
1.06 
.72 
3.48 
T 1.31 
22.24 
16.25 49.92 
1915 
.66 
.98 
.90 
4.00 
1.59 
.71 
3.13 
2.28 
2.94 
.67 
T .27 
18.13 
14.65 52.50 
1916 
.70 

.09 
1. 55 
.56 
.63 
.98 
4.43 
. m . 78 
.29 .32 
10.89 
8.71 58.90 
1917 
.31 
.11 
.12 
.32 
1.82 
.90 
.74 
6. 11 2. 74 . 16 
.62 .04 
13.99 
12.63 63.4.: 
1918 
.10 
.13 
.21 
1. 14 
.21 
.80 
2.54 
1. 02! 2. 85 2. 60 
. 5l| 2. 00 
14.11 
8. 56 64. 68 
1919 
.04 
.32 
3.69 
3.61 
5.84 
6.39 
3.16 
2.53 4.16 2.31 
.51 .93 33.49 
25. 69 45. 79 
1920 
.76 
.15 
.34 
.20 
2. 55 
3.91 
1.52 
1.48 1.44 
3.68 
.49 
16.52 
11.10 - it 
1921 
1.11 
.32 
.83 
T 
8.63 
5.88 
3.56 
1. 95 . 7: 
.21 

23.24 
20.77 48.10 
Average: 
1914 to 1921 
.50 
.30 
.84 
1.67 
3. 31 
2. 75 
2.44 
2.61 2.02| 1.74 
.30 
.61 19.08 
14.80 54.03 
1905 to 1921 
.36 
.58 
.70 
1.68 
2.17 
2. 17 
2.59 
2.82 1.55 1.28 
1 
.79 
.71 17.40 
12.98 
The length of the frost-free period and the prevalence of effective 
growing temperatures (those above 50° F.) are important factors in 
sorghum production. The frost-free periods at different field stations 
are shown in Figure -t; also the earliest and latest dates of the last 
killing frost in the spring and the first killing frost in the fall. 
Comparison of the average frost-free periods at these different 
stations with the average growing periods required for the earlier 
sorghum varieties indicates that in most instances these early varie- 
ties should mature at even the most northern stations; but the low- 
temperatures that generally follow the last frost in the spring and 
precede frost in the fall retard the development of the sorghum -<> 
much that it does not mature within the time required for completing 
r - growth farther south. Where such varieties as the Dakota Amber 
do mature, the yields are so low that their forage value is interior t<> 
that of corn or only slightly better. For this reason the sorghums 
have remained unimportant in the northern Great Plains, even 
though the need of such a drought-resistant crop in that section i- 
generally recognize* 1 . 
