SOIL SURVEY OF THE MIDDLE GILA VALLEY, ARIZONA. 



25 



alkali are present, but injurioiis quantities occur in the western and 

 northwestern parts. 



While much of the McClellan clay loam is without vegetation, 

 parts of it have a growth of mesquite, sage, and dwarf cactus. The 

 occasional presence of standing water, followed by a baked condition 

 of the soil, renders the broad fiats occupied by this type unsuited to 

 the native plants even where the content of alkali is low. The bar- 

 ren areas are known locally as " slicks." 



The soil is used to some extent for pasture. Owing to the generally 

 poor physical condition of the soil, the poor drainage, the alkali 

 accumulations, and the cost of reclamation, farming has not been 

 attempted except in a few of the more favorable situations. Grain 

 is the principal crop grown. Where the subsoil conditions are better 

 than typical and the soil is free from alkali, good yields are obtained 

 under irrigation, but the selling value of the land is low. 



The table below gives the results of mechanical analyses of samples 

 of the soil and subsoil of the McClellan clay loam : 



Meclxnnkal analyses of McClellan clay loam. 



GILA FINE SAND. 



The Gila fine sand consists of a friable, brown fine sand, 3 to 6 feet 

 deep, underlain by variably textured stratified sediments. The 

 mellow, open soil is not as high in organic matter as the Gila silty 

 clay loam, but it is moderately well supplied. It absorbs moisture 

 easily, but does not retain it as well as the silty clay loam. The soil 

 is micaceous and well supplied with lime. In poorly drained areas 

 the subsoil is often slightly more compact and lighter colored than 

 the surface soil, but it is favorable to root development except where 

 waterlogged. 



In local areas adjacent to the Gila River the soil is more silty than 

 typical, and sometimes a light fine sandy loam in texture, while along 

 the Little Gila it contains more sand and fine sand. The subsoil is 

 highly calcareous. Small amounts of gravel occur locally along the 

 streams. Two small islands in the Gila River are clas.sed Avith the 

 type, although the soil is coarser textured than typical. The channels 

 of the Gila and Little Gila Rivers are occupied by material similar 

 to this soil, but owing to their position they are classed with River- 

 wash. 



