18 



FIELD OPERATIONS OF THE BUREAU OF SOILS, 1903. 



strata of sand or gravel the underdrainage is poor. The surface drain- 

 age is also often deficient. A considerable proportion of the cultivated 

 area of this soil type has been damaged by this lack of drainage and 

 b}^ seepage from adjoining soils, and should be artificially drained. 



This soil is formed by the deposition of the heavier silt and alluvial 

 material carried by the Gila River and its tributaries, vast quantities 

 of which are brought down and deposited by these streams in times 

 of flood. 



The Maricopa silt loam contains an abundance of organic matter and 

 mineral plant food. It also carries normally in the subsoil, often at 

 great depths, large quantities of alkali. When localized within the 

 first 6 feet of the surface this may be, and usually is, present in dan- 

 gerous quantities, and in nearly all the areas of this type which have 

 been irrigated for some length of time there has been in many places 

 an injurious accumulation in the surface soil. 



This soil, owing to its close texture, tendency to puddle and bake, 

 and sticky condition when wet, is somewhat refractory and is culti- 

 vated with considerable difficulty. Deep plowing, the application of 

 straw or coarse stable manure, and frequent and thorough cultivation 

 are necessary to improve the physical condition of the land. In areas 

 damaged by seepage water or alkali this treatment should be supple- 

 mented by thorough artificial drainage. When not damaged by alkali 

 or seepage water, and properly cultivated, this soil yields heavy crops 

 of alfalfa and grain. 



The Maricopa silt loam is best adapted to alfalfa, wheat, barley, 

 sorgum, Egyptian and Indian corn, and sugar beets. In those places 

 where the alkali salts exist in excess sorghum, beets, and alfalfa will 

 be found to give the best results. 



The following table shows the texture of this soil type: 



