GEAIN-SOEGHUM EXPERIMENTS IIST THE PANHANDLE OP TEXAS. H 



unfavorable distribution of the large and important seasonal rainfall. 

 Figure 2 shows in graphic form the annual and seasonal rainfall 

 (April to September, inclusive) during the 10-year period from 1907 

 to 1916, inclusive. 



Unfavorable distribution may occur in various ways. Much or 

 most of the seasonal rainfall may come near the beginning or toward 

 the end of the growing season. While the total quantity may have 

 been about normal, protracted drought may have occurred during 

 some part of the year. The occurrence of spring droughts in 1907 

 and 1909 is shown in Table II. In these years no effective rains fell 

 mitil the middle of June. The same conditions prevailed to a lesser 

 extent in 1913* while the autumn also was unusually dry. 



In the second case, a considerable rainfall may come aU at the 

 beginning of one month and again at the end of the following month. 

 Several weeks of drought may have intervened between two rainy 







































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Fig. 2.— Diagram showing the seasonal (April to September) and annual precipitation, in inches, at Ama- 

 rillo, Tex., during the 10-year period from 1907 to 1916, inclusive. 



periods, although the total precipitation in each of the two months 

 was about normal. A study of the daily precipitation record of the 

 years 1911, 1912, and 1913 in Table II will illustrate this condition. 

 In 1911 there was no effective rain between July 21 and August 22, 

 though the rainfall in both months was good. In 1912 there was no 

 effective rainfall between June 11 and July 17, and in 1913 from June 

 12 to July 25, although the total precipitation in each of these months 

 except the last was satisfactory in quantity. 



A third condition occurs in which a rainfall may be evenly dis- 

 tributed in point of time and about normal in quantity and yet be 

 deficient for crop production. This is when it occurs in the form of 

 light showers which do not penetrate the soil and are soon evaporated. 

 Several showers of about a quarter inch each may add no water to 

 the soil if followed by drying winds and bright smishine, which cause 

 rapid evaporation. Such showers are then of little or no value to the 

 growing crop. The months of June, July, and August, 1912, and 

 June, 1913, are examples of this condition, as may be seen in Table II. 



