SOIL SURVEY OF THE MIDDLE GILA VALLEY, ARIZONA. 35 



concentration of salts were brought to a productive state by repeated 

 flooding over several seasons, and further improved by irrigation and 

 cultivation. 



The elevation and sul)soil characteristics of the alkali lands greatly 

 influence the possibility of reclamation. The mere flooding of the 

 upland soils frequently removes enough alkali to permit the growing 

 of crops, where the subsoil is not too compact and impervious, but in 

 the bottoms the usually high water table must be lowered by resort- 

 ing to artificial drainage before the lands can be permanently re- 

 claimed. Many tracts of land in the Gila bottoms have been made 

 productive merely by repeated flooding, but when cultivation and 

 irrigation cease for several seasons these soils tend to revert to their 

 former condition. Soils containing small amounts of alkali, evident 

 only in level spots, produce well when properly cultivated and irri- 

 gated. In upland areas of high salt concentration where there is an 

 impervious subsoil several feet in thiclmess, and in many of the badly 

 affected bottom soils, the cost of permanent reclamation by means of 

 drainage and flooding is prohibitive under present economic con- 

 ditions. 



SUMMARY. 



The Middle Gila Valley area includes the bottom and terrace lands 

 of the Gila River from a point about 5 miles northeast of Florence 

 to Sacate and a part of the desert plains east and south of the Sacaton 

 Mountains. Almost all the territory lies in Pinal County. The 

 survey covers 352 square miles, or 225,280 acres. 



Elevations range between 1,150 feet and 1,525 feet above sea level. 

 Several small buttes within the area and the included parts of the 

 adjacent mountain slopes are stony and of little agricultural value. 



The Gila Eiver is the principal drainage way in this part of the 

 vState. McClellan Wash and Santa Cruz Wash drain the greater 

 part of the desert plains within the area. The channel of the Gila 

 River is broad, with poorly defined banks, and overflows are frequent. 

 The channels of the McClellan and Santa Cruz Washes are poorly 

 defined and have little fall, much land being flooded at irregular 

 storm periods along their courses. 



The population of Pinal County in 1910 was 9,045. Nearly one- 

 third of this consisted of Indians on the Gila River Indian Reserva- 

 tion. There are many Mexicans and small numbers of Negroes, Chi- 

 nese, and Japanese. There are two incorporated towns in the area 

 and several Indian villages. Florence is the largest town and the 

 county seat of Pinal County. 



The Southern Pacific Railroad and the Arizona Eastern Railway 

 touch the area, but most of the farms are remote from shipping 

 points. 



