GRAIN-SORGHUM EXPERIMENTS IX OKLAHOMA. 
growing months in the years 1918 to 1921, inclusive. The distance 
between the two points of observation is about 1^ miles, the Weather 
Bureau records being taken in the town, which is located in the 
valley of the North Fork of the Canadian River. It is to be noted 
that the rainfall at the Weather Bureau station averages higher 
than that at the field station, which is due to the fact that many 
of the summer showers follow the river valley. Frequently, good 
showers occur in town when little or no rain falls at the field station, 
which is situated on higher bench land. 
Table 3. — Precipitation at the United States Weather Bureau station, Woodward, Okki., 
compeared with that at the Woodward Field Station during the 6 months from April 
to September for the years 1918 to 1921, inclusivl . 
[Data in inches.] 
Year and station. 
Apr. 
May. 
June. 
July. 
Aug. 
Sept. 
Seasonal. 
1918: 
United States Weather Bureau 
2.51 
2.22 
4.87 
4.10 
1.12 
1.06 
1.85 
1.80 
4.49 
4.00 
4.63 
4.29 
4.19 
3.40 
1.55 
1.91 
2.11 
1.91 
3.76 
2.22 
1.31 
1.29 
8.00 
5.78 
1.79 
.73 
1.91 
1.35 
5.44 
4.69 
3.15 
2.50 
0.70 
1.35 
1.72 
1.87 
2.62 
3.00 
6.85 
5.11 
1.26 
1. 24 
.56 
.63 
6.34 
5.01 
2.90 
2.94 
12. 86 
Woodward Field Station 
11. 45 
1919: 
17.4" 
14. 46 
1920: 
United States Weather Btfreaa 
21. 02 
Woodward Field Station 
18.45 
1921: 
24.30 
20.04 
The precipitation data given in Table 1 are those recorded at the 
Weather Bureau station, as they are available for a greater period 
of years than the field station records. It must be remembered 
that the precipitation data given in Table 1 are somewhat high for 
the conditions under which the experiments were conducted. The 
data in Table 2 were obtained at the field station and show precipita- 
tion conditions under which the crops were actually grown. 
HUMIDITY. 
The atmospheric humidity of this section is usually low. Humidity 
decreases and wind velocity increases from central Oklahoma west- 
ward. The relatively low humidity at Woodward is doubtless corre- 
lated with high transpiration from growing crops, as low humidity 
is one of the chief factors favorable to high evaporation. The 
relative atmospheric humidity has been determined from wet and 
dry bulb readings taken at the W T oodward Field Station during the 
six months from April to September, inclusive, for the eight years 
in which these experiments have been conducted. The relative 
atmospheric humidity is given in Table 4, together with other 
climatic data. 
WIND. 
Data on wind velocity are shown with other climatic data in 
Table 4 for the crop season (April to September) during the 8-year 
period from 1914 to 1921, inclusive. The wind velocity for* the 
season averages high. Some days are calm, followed by days of 
high wind movement. The highest wind movement for one day 
during the period reported was 608 miles, on April 11, 1920. This 
is an average of more than 25 miles an hour for 24 hours. These 
wind data were recorded by an anemometer at the field station 
49019— 23— Bull. 1175 2 
