SOIL SUEVEY OF THE MIDDLE GILA VALLEY, ARIZONA. 27 



The type as mapped includes some variations. While the color of 

 tlie surface soil is uniform for so extensive a type, some areas have a 

 darker color, owing to a larger admixture of organic matter. In de- 

 pressions the soil is both heavier and darker than the typical soil, 

 and on some narrow ridges it is coarser and lighter. As mapped 

 some material of silt-loam texture is included. AVhere.poor drain- 

 age exists and alkali has accumulated the subsoil is usually lighter 

 colored and more compact than the subsoil in other parts of the type. 

 Harmful concentrations of soluble salts occur over a large part of 

 the type. The substratum is similar to the subsoil to a depth of 

 many feet. Below this are l)eds of river gravels. 



The Gila silty clay loam is an extensive and important soil occu- 

 pying the greater part of the Gila River bottoms. The surface is 

 generally level and moderately smooth, well adapted to irrigation 

 and cultivation (see PI. II, fig. 1). The sandier ridge areas require 

 leveling before they are farmed. Much of the type lies on a second 

 terrace a few feet above the normal overflow of the river. On the 

 whole it is not thoroughh^ drained, and much of it as the result of 

 seepage has a high water table. Capillary movement of moisture is 

 rapid and much of the type is damaged by alkali, small tracts being 

 barren of vegetation. AYhile not often overflowed by fl(^ods in the 

 Gila River it is subject to overflow from other sources. Mesquite. 

 greasewood, seep weed, and a little salt grass are the characteristic 

 plants in the vegetation. 



The Indians have farmed parts of the Gila silty clay loam for 

 many years, growing wheat, barley, hay, alfalfa, corn, sorghums, 

 and, recently, cotton. Truck and root crops are grown locally. Be- 

 cause of its low-lying position the type is not well adapted to fruit 

 culture. Large areas are unproductive because of the excessive ac- 

 cumulations of alkali, but in the eastern part of the area less alkali 

 is present, arid the white farmers here produce good crops of grain. 

 The Indians get only fair yields on this type, considerably below 

 those obtained by the white farmers. The uncultivated areas of the 

 type are used as pastures. All crops are grown under irrigation, 

 water being obtained from the Gila River and by ])umping from 

 wells. Much of this type within the Indian reservation is under a 

 canal system installed by the Government. Reclamation is accom- 

 plished by checking the land and flooding it for several months or for 

 several seasons, depending upon the concentration of salts. Much of 

 the type requires artificial drainage. No fertilizers are used and crop 

 rotations are seldom followed. 



The price of land of this type depends largely upon its condition 

 for farming and the location. Little of it has changed hands re- 

 cently and the Indian lands are not sold. Prices range from as low 



