SOILS OF THE EASTERN UNITED STATES AND THEIR USE-XXXIII. 



THE CARRINGTON CLAY LOAM. 



GEOGRAPHICAL DISTRIBUTION. 



The Carrington clay loam is an extensive and valuable general 

 farming soil found in the North Central States. It has been encoun- 

 tered in six different soil-survey areas in the States of North Dakota, 

 Iowa, Minnesota, and Wisconsin and mapped to a total extent of 

 612,864 acres. The existence of considerable additional areas has 

 been indicated by soil surveys already made, and it is probable that 

 the type will eventually be found to cover an area in these States in 

 excess of 6,000,000 acres. 



CHARACTERISTICS OF SOIL AND SUBSOIL. 



The Carrington clay loam, to an average depth of 12 or 14 inches, 

 consists of a very dark-brown to black heavy loam or silty loam, 

 grading at depths frequently in excess of 14 inches into a brown 

 .silty clay loam, which at about 24 inches becomes a yellow clay loam. 

 The surface soil is almost universally high in organic matter, rep- 

 resenting a long-continued accumulation of decomposed vegetation, 

 which renders the soil more friable and easier to till than is com- 

 monly the case with such a heavy loam or clay soil. Stone or gravel 

 are usually absent in the surface soil, but the deeper subsoil fre- 

 quently contains both, with small local areas, in the more rolling 

 portions of the type, where stone and bowlders are abundant in both 

 soil and subsoil. 



In almost all areas where the type is found it is underlain by lime- 

 stone rock at depths ranging from 10 to 50 feet, and a considerable 

 amount of limestone fragments and gravel has been worked into the 

 soil and subsoil. Even where the type rests upon other classes of 

 rock the glacial till from which it is derived contains appreciable 

 amounts of calcareous material, and the subsoil is universally marked 

 by a rather high content of calcium carbonate. 



Like the other members of the Carrington series, this soil is char- 

 acterized by the dark color of the surface soil, the yellow or brownish- 

 yellow color of the subsoil, and by its derivation from glacial till. 



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