DEPARTMENT OF BOTANY. 



RANGE IMPROVEMENT. 



This division of the department's work has been conducted 

 in co-operation with the Division of Agrostology, U. S. D. A., 

 according to arrangements made with the U. S. Secretary of 

 Agriculture. 



The range improvement work in Arizona, being of a differ- 

 ent character than that usually contemplated, and being in a re- 

 gion more completely divested of range grasses than probably 

 any other in the entire country, required considerable careful 

 study beforehand in order to discover the proper locality for ex- 

 perimentation. Accordingly, considerable time was spent in a 

 survey of the surrounding country in the vicinity of Tucson, for 

 the purpose of determining which of three typical areas 

 (mesa, foothill, or river bottom) would be the most favorable and 

 give the most conservative and valuable data upon which to base 

 judgment of the results obtained by experimentation. Finally, a 

 rather favorable mesa area was selected at an altitude of about 

 twenty-six hundred feet above sea level, and about four hundred 

 feet higher than the city of Tucson. This tract, which was sub- 

 sequently reserved from entry at the request of the Honorable 

 James Wilson, United States Secretary of Agriculture, is des- 

 cribed in the government surveys as Sections 26, 27, 34 and 35; 

 T. 14 S., R. 14 E., Gila and Salt river meridian. 



Somewhat diagonally through the center of this area runs 

 the Southern Pacific railway, and a short distance to the east of 

 it is located Wilmot siding. The soil is a clay loam, mixed with 

 considerable sand, and subtended at a depth of two to two and 

 a half feet by a calcareous hardpan known among the Mexicans 

 by the significant name, " Caliche." The slope, which is rather 

 gentle, has a general northwesterly direction, and is traversed by 

 three more or less distinct, broad, shallow depressions which re- 

 ceive the drainage of a considerable area of land to the southeast. 

 Such a region, with broad, shallow washes, was purposely se- 



