THK DEKALB STLT LOAM. 5 



The Dekalb silt loam exists through a wide range of elevation,, 

 as might be anticipated in the case of a plateau and mountain soil 

 of such wide distribution. In southern Indiana and in Kentucky 

 the surface of the type is only about 750 to 800 feet above sea level. 

 From this low altitude the main development of the type rises east- 

 ward through the Plateau Region to altitudes of 2,000 feet or more 

 in eastern Tennessee, northern Alabama, and north-central Pennsyl- 

 vania. Probably the greater proportion of the type is to be found 

 at altitudes between 1,000 and 1,800 feet above tide level. Thus, 

 even in more southern localities, the Dekalb silt loam is found under 

 climatic surroundings which give to it an agricultural value more 

 consonant with more northern localities; while in the northern re- 

 gions of its occurrence some portions of the type are actually found 

 above the altitudes at which the staple farm crops may be grown to 

 advantage. 



The majority of the areas of the Dekalb silt loam are well drained. 

 This is chiefly due to the generally elevated position of the type, to 

 the fact that there are usually accumulations of sandstone and sandy 

 shale fragments in the deeper subsoil, and to the additional fact that 

 it normally rests upon a bed of sandstone from which it is chiefly 

 derived. There are, however, many small local areas and some con- 

 siderable tracts, chiefly those to be found in valley positions, which 

 are marked by stiff, clayey, mottled, and poorly drained subsoils, and 

 which would be decidedly benefited by artificial drainage. Such 

 areas are either found to be in forest or else, where they have been 

 cleared, they are chiefly utilized for pasturage purposes. Generally 

 the drainage of the Dekalb silt loam is excellent, and there is more 

 liable to be difficulty from a deficiency of moisture during the grow- 

 ing season than from excess. 



Upon the more sloping areas of the Dekalb silt loam and fre- 

 quently around the margins of any area of the type there is liable 

 to be some difficulty experienced on account of erosion. The major 

 streams which flow out from the Plateau and many of their smaller 

 tributaries have trenched deeply into the upland surface, and the 

 headwaters of all of these streams are eroding rapidly. There is a 

 constant tendency, thus, to invade the more level plateau surface 

 and toward the removal of both soil and subsoil material. Within 

 the larger areas of the type there is little danger from erosion, owing 

 to the level or gently rolling surface of the soil. In order to prevent 

 the further destruction of areas of the type from marginal erosion, it 

 is most desirable that all steeply sloping areas should be left in 

 forest and woodlot or devoted, upon the gentler slopes, to the pro- 

 duction of grass for pasturage. Under cultivation the soft, silty 

 soil is otherwise easily removed by flowing water. 



