SOILS OF THE EASTERN UNITED STATES AND THEIR USE XXXII. 



THE CARRINGTON SILT LOAM. 



GEOGRAPHICAL, DISTRIBUTION. 



The Carrington silt loam is an important and widely distributed 

 general farming soil, occurring chiefly in the northwestern portion 

 of the upper Mississippi Basin. It has been encountered in seven 

 different soil-survey areas in five States, and has been mapped to a 

 total extent of 739,584 acres. It is probable that additional soil- 

 survey investigations will show that this type has an area of not less 

 than 7,500,000 acres. 



CHARACTERISTICS OP SOIL AND SUBSOIL. * 



The surface soil of the Carrington silt loam to an average depth of 

 12 inches consists of a dark-brown to black silt loam, usually soft and 

 friable and high in organic matter. The subsoil ranges from a dark 

 yellowish brown to pale yellow silty clay loam, with a gradation 

 downward in many cases into a more compact and dense clay loam of 

 the same color. While the type as a whole is not marked by the 

 presence of stone or gravel, there is usually a small quantity of stony 

 material in the surface soil and this increases with depth until the 

 deep subsoil grades into a stony or gravelly glacial till. Upon the 

 low ridges which occur within the type there are usually areas more 

 stony than in the undulating or level areas. There are also frequent 

 small gravelly knolls or ridges crossing the fype, though comprising 

 a different class of soil. 



The Carrington silt loam differs from the Marshall silt loam, with 

 lich it is sometimes associated, in that it is derived from the 

 weathering of the glacial till and as a result is liable to contain stone 

 and gravel, as contrasted with the stone-free character of the Mar- 

 shall silt loam. The almost universal presence of stony material in 

 the deeper subsoil of the Carrington silt loam is the chief feature 

 distinguishing it from the other dark-colored silty prairie soils of 

 the general region in which it occurs. The presence of the gravelly 

 and stony ridges is also a marked characteristic of the type. 



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