10 SOILS OF THE EASTERN UNITED STATES. 



Over a considerable proportion of the area of the Clarksville silt 

 loam there is no essential topographic reason why the soil should not 

 be tilled aside from its remoteness from the main routes of transpor- 

 tation. 



As population becomes more dense, many thousands of acres of this 

 type may be added to the tilled areas of the States where it occurs. 



i 



CROP ADAPTATIONS. 



Throughout its entire extent in all localities the Clarksville silt loam 

 is largely utilized for the production of corn. There is a great varia- 

 tion in yield, not only between the different regions occupied by the 

 type, but also when the yields of different farms in the same area are 

 compared. It is, therefore, difficult to state average yields for the type 

 or to determine its relative rank as a corn-producing soil. In general, 

 however, the yields are low. In Alabama, Arkansas, and southern 

 Missouri the average yield is probably from 10 to 15 bushels per 

 acre, which is scarcely sufficient to pay for the trouble of planting. 



In the western parts of Kentucky and Tennessee the yields vary 

 from 20 to 40 bushels per acre, and corn is one of the important crops 

 produced upon the type. At the higher altitudes in Kentucky and 

 Tennessee the yield again sinks to 12 or 15 bushels per acre. The 

 lower yields in the production of corn are almost always associated 

 with the occurrence of the type at higher altitudes and with the pres- 

 ence of a stiff, retentive subsoil at no great depth beneath the surface. 

 On the other hand the higher yields of western Tennessee and Ken- 

 tucky are usually associated with the well-drained soil and subsoil, 

 and particularly with the presence of the layers of chert nodules at a 

 depth of about 2 feet in the subsoil. Thus the factors of climatic 

 surroundings and of subsoil drainage largely control the quantity of 

 corn produced upon this type. This arises principally from the fact 

 that while the crop may obtain sufficient moisture during the earlier 

 part of the season, even when grown upon the portions of the type 

 having the most dense and compacted subsoil, it is totally unable to 

 secure an adequate amount of moisture during midsummer and dur- 

 ing the ripening stages of the grain. The removal of this fundamental 

 limitation through tile drainage, through plowing the soil to increas- 

 ingly greater depths, and in certain instances through subsoiliiig, 

 would greatly Improve this soil for the production of corn. 



Wheat is an almost universal crop upon the Clarksville silt loam. 

 There is a considerable range in the yields secured in the different 

 sections occupied by the type. In Alabama, Arkansas, and southern 

 Missouri yields of 5 to 12 bushels are normal, while a yield of 15 

 bushels or more is considered exceptional. The more elevated 

 areas of the type in central Tennessee and Kentucky produce at 

 about the same rate, while the lower lying areas in western Tennessee 



