_GRAIN-SORGHUM EXPERIMENTS IN THE PANHANDLE OF TEXAS. 1] 
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 
until 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 all 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 
£907 1908. 4909 49/0 19/1 SH2 SWF 19/14 SE SHE 
Fic. 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 in was satisf actory 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 oceurs in the form of 
hight 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 sunshine, 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. 
