6 SOILS OF THE EASTERN UNITED STATES. 



LIMITATIONS IN USE. 



That the proper uses of the Dekalb silt loam are somewhat re- 

 stricted under present conditions surrounding the greater part of the 

 type is well shown by the large proportion of it which still remains 

 in forest. There are several reasons why this type has not been more 

 extensively cleared and tilled. 



A large part of the more eastern development of the Dekalb silt 

 loam is to be found at considerable elevations, upon the crests of high 

 ridges or upon the summits of the plateau lands. These areas are 

 not particularly accessible, either for the purposes of obtaining the 

 supplies for the farms or for the purposes of disposing of bulky farm 

 products. The roads are infrequent and very often of steep grade 

 between the farm and the market place. In northwestern Pennsyl- 

 vania and in eastern Tennessee and northern Alabama this fact has 

 prevented the extensive occupation of the type even after it had been 

 largely cleared of its original forest growth. At lower altitudes, as 

 in West Virginia, Kentucky, Ohio, and Indiana, the Dekalb silt loam 

 is found nearer to the established lines of transportation and of high- 

 way communication. In all such areas a much larger proportion of 

 the type has been cleared and brought under cultivation. This estab- 

 lishes the fact that altitude and lack of transportation have been 

 among the chief obstacles to the more extended use of the type. 



The high altitude of large portions of the type has also been re- 

 sponsible for other limitations upon the use of the Dekalb silt loam. 

 In its more northern localities, in north-central Pennsylvania, the 

 season is usually too short to permit of the maturing of corn for 

 grain, and this crop is eliminated. In such localities buckwheat, 

 oats, and timothy are the only crops which may be extensively 

 grown, with potatoes as a supplementary crop. Farther to the south 

 the climatic surroundings are so changed that even cotton may be 

 grown, with limited success, upon the type, and there the oats and 

 even wheat of the intermediate regions do not thrive because of 

 climatic environment. Thus, in various parts of its broad extent, the 

 Dekalb silt loam is limited in its uses to those crops which may be 

 appropriately grown under the existing climatic conditions. The 

 limiting factor of climate is usually that of temperature, as expressed 

 both by length of growing season and by the mean temperatures 

 during the periods when the crops occupy the land, since the attend- 

 ant rainfall is commonly adequate. 



In all regions where it occurs, under such extraneous conditions as to 

 render agricultural occupation desirable, the Dekalb silt loam is lim- 

 ited to the production of the staple farm crops through its textural 

 characteristics. While the surface soil is mellow and easily tilled over 

 a considerable part of the extent of the type, the subsoil is usually 



