BOTANY 



J. J. Thornber 



The year ended June 30, 1921, was one of the driest in 

 the history of the stock-raising industry in Arizona, the 

 drought being especially severe in the southern half of the 

 State. The rainfall at Tucson, Arizona, for this twelve-month 

 period was 6.32 inches which is slightly more than one-half 

 the yearly average for this location. Of this amount, 4.38 

 inches or 69.3 percent fell during the summer growing season, 

 July to October inclusive, and 1.72 inches or 28.2 percent 

 during the winter and spring months, November to April in- 

 clusive. At Tucson no rain fell in May and but .22 inches in 

 June. Similar conditions prevailed generally throughout south- 

 ern Arizona. Rains varying from one to two or three inches in 

 depth fell in various parts of central and northern Arizona 

 late in the winter and spring months. Only at altitudes of 

 5500 feet and above, however, were these rains sufficiently 

 heavy to make possible a fair growth of the spring grasses 

 and similar plants. This growth was particularly good in the 

 country about Flagstaff and Williams. The precipitation for 

 the year came generally as showers which, though beneficial 

 to plant growth, were not lasting in their effects, since the 

 moisture did not penetrate to any considerable depth in the 

 soil and hence was soon dissipated by the dry winds. 



EFFECTS OF SCANT RAINFALL 



As a result of the scant rainfall noted above, growth on 

 the grazing ranges during the summer and fall of 1920 was 

 greatly reduced, being generally not more than twenty-five to 

 thirty-five percent of the average, while practically no growth 

 took place late in the winter and spring months, except as 

 already noted at the higher altitudes. It was to be expected, 

 therefore, that heavy losses of stock through starvation would 

 result on the ranges. In the southern and eastern parts of the 

 State in particular, with a shortage of both feed and water, 

 losses on many grazing ranges were heavy. It is stated that 

 in some instances as high as thirty-five to fifty percent of the 

 stock died and that many of the remaining animals were left 

 in an emaciated, half-starved condition. 



