BROOM-CORN EXPERIMENTS AT WOODWARD, OKLAHOMA. 3 



been eroded more than the soils of the western part. The soil 

 types found in this extensive area vary from sand to clay, with the 

 loams predominating in the southern and central parts of the area 

 and silt loam in the northern. All are friable and easy to cultivate 

 as compared with similar types under more humid conditions. They 

 are uniformly sweet or nonacid, and under natural conditions contain 

 from 3 to 6 per cent of organic matter. In general, low yields are 

 due to some climatic factor or factors rather than to a lack of 

 soil fertility. 



CLIMATIC CONDITIONS. 



The weather data considered herein were recorded at Wood- 

 ward, Okla., during the period from 1908 to 1918, inclusive. 

 Woodward is located centrally in the district described. 



The principal climatic features which influence crop production 

 in this section are (1) a limited annual precipitation of irregular 

 seasonal distribution and a great loss of water due to run-off during 

 torrential summer storms, which are quite common in some locali- 

 ties; (2) a relatively low atmospheric humidity; (3) a very high 

 rate of evaporation during the summer months; (4) a wide daily 

 range of temperature, or hot days followed by cool nights; and 

 (5) a high average wind velocity. 



Precipitation. 



Precipitation and its distribution are important factors in crop 

 production in the section under discussion. There is usually rain- 

 fall enough to grow the crop, but the distribution is not always 

 such as to permit the best use by the crop of the moisture which 

 falls. In such cases the crop yields are very low, and in extreme 

 cases total failure results. 



MONTHLY AND ANNUAL PRECIPITATION. 



Table I shows the monthly, annual, and mean annual precipitation, 

 in inches, at Woodward, Okla., during the 11-year period from 1908 

 to 1918, inclusive. The mean annual precipitation at Woodward for 

 this 11-year .period was 24 inches, of which amount 16.5 inches fell 

 during the growing season, or from April to September, inclusive. 



Table I shows a wide fluctuation in both the monthly and the 

 annual precipitation. In April, 1909, the rainfall was 0.45 inch, and 

 for the same month in 1915 it was 7.08 inches, or a difference of 

 more than 6 inches between these extremes. May, June, July, 

 August, and September each have about the same range of fluctua- 

 tion as April. In the annual precipitation the extreme range is from 

 14 inches in 1910 to 39 inches in 1915, almost three times as great. 



