8 SOILS OF THE EASTERN UNITED STATES. 



of the type to such an extent as to destroy them for agricultural 

 purposes. 



It is extremely fortunate under these circumstances of prevalent 

 excessive erosion that the subsoil materials and the parent loess are 

 capable of becoming transformed into fertile and productive soil 

 within a very brief period of time, provided proper care is taken to 

 plow the subsoil material thoroughly and to incorporate organic 

 matter for the formation of a complete soil. There are very few 

 soils in the United States, and practically none except those derived 

 from similar deposits of loess, which show such marked character- 

 istics of speedy recuperation from excessive erosion. 



LIMITATIONS IN USE. 



The principal limitation to the use of the Memphis silt loam for 

 the production of cultivated crops lies in the tendency toward exces- 

 sive erosion already mentioned. The type taken as a whole may only 

 be tilled to the extent of 15 to 20 per cent of its total surface area in 

 the " Cane Hill " regions, and to the extent of about 30 or 40 per cent 

 of its surface in the more gently undulating portions of its develop- 

 ment. The balance of the type must be left either in forest upon th<? 

 steeper slopes or covered with the native grasses upon the more gen- 

 tle slopes, not only for the protection of these slopes themselves, but 

 also to prevent the invasion of tilled areas through the formation of 

 gullies and of deep washes. This limitation, of course, applies only 

 to the area which may not be tilled and not to the portions where 

 crops may be grown. 



Excessive erosion in many instances has also adversely affected the 

 depth and condition of the surface soil of the Memphis silt loam. 

 Although even in the most eroded areas a surface soil may be de- 

 veloped by proper cultural methods in two or three years time, there 

 are considerable areas where the requisite organic matter for the 

 formation of a complete surface soil is only present to a depth of 

 2 or 3 inches. In all such areas and even over a considerable pro- 

 portion of the tilled fields upon the Memphis silt loam the incorpora- 

 tion of organic matter is one of the prime necessities for the produc- 

 tion of adequate crop yields. In all areas where the type is found, 

 whether in the more northern grain-growing sections or in the moi 

 southern cotton-producing areas, the restoration of organic matter 

 to the Memphis silt loam constitutes an important problem for the 

 maintenance of the type under agricultural occupation. 



The tillage difficulties encountered in the use of the type consist 

 chiefly in those resulting from a tendency toward erosion. The soil 

 itself is soft, friable, easily broken, and easily tilled. Drainage 

 a problem only to a limited extent over the flatter portions of the 

 type, and throughout its extent it is stone free, and not encumbered 

 by other obstructions to tillage except the gullies already mentioned. 



