THE KNOX SILT LOAM. 9 



provement in the soil itself, although temporary increases are ob- 

 tained in the crop to which the material is applied. A far better 

 method for the fertilization of the land would be the application of 

 all possible organic manures, supplemented by the plowing under 

 of green crops and of sod, with the application of some form of 

 phosphatic fertilizer to be indicated by experimentation upon the 

 land to be treated. 



LIMITATIONS UPON SPECIAL CROPS. 



Very few special crops are grown upon the Knox silt loam. In 

 the Ohio River district of southern Indiana and western Kentucky a 

 considerable acreage is devoted each year to the production of the 

 heavy export tobacco. Whenever the economic conditions are such 

 that there is an adequate demand for a greater quantity of this class 

 of tobacco its cultivation might be extended over considerable areas 

 of the Knox silt loam in southern Indiana and south-central Illinois. 

 There is little incentive in the current prices for such an extension. 



Apple orcharding has assumed an important place in the utiliza- 

 tion of certain areas of this type. Only the better drained areas of 

 the Knox silt loam, chiefly those occurring adjacent to the hilly and 

 broken land along the major streams, should be selected for such 

 plantings. Such a location is requisite, not only to secure adequate, 

 soil drainage, but also to secure air movement and air drainage 

 to ward off unseasonable frosts. In certain of the Missouri areas 

 extensive plantings of apples have been made upon the type, and the 

 strong growth of the trees, the fact of their early bearing, and the 

 fair to good quality of the fruit all indicate that in favorable situa- 

 tions, particularly in northern Missouri and in Iowa, Wisconsin, 

 Illinois, and north-central Indiana, apple orcharding might become 

 an important industry upon the Knox silt loam. In fact, in many of 

 the prairie counties in this general location the Knox silt loam is the 

 only soil type which is well enough drained and properly located with 

 regard to air circulation for the planting of large commercial or- 

 chards. A considerable proportion of the more gentle slopes, which 

 is now occupied by native timber, might well be cleared and planted 

 to those varieties of apples suited to production upon the heavier 

 soils of the central prairie region. These include Wealthy, Jona- 

 than. Winesap, Ben Davis, Gano, and Red Astrachan. The total 

 area of the Knox silt loam possessing both the requisite slope and 

 drainage condition for orchard planting is somewhat limited, 

 although many thousands of acres could thus be utilized. 



EXTENT OF OCCUPATION. 



Since the Knox silt loam is developed in certain localities as an 

 undulating to gently rolling type, and in others as a hilly to even 

 97998 Cir. 3311 2 



