6 SOILS OF THE EASTERN UNITED STATES. 



LIMITATIONS IN USE. 



On account of its silty texture and of the rather dense structure of 

 the subsoil the Knox silt loam is not particularly well suited to the 

 production of any except the general farming crops, including corn, 

 the small grains, and grass. In some local areas potatoes have been 

 found to give excellent yields over the small areas planted to that 

 crop, and it is probable that any special crop adaptation for this type 

 should follow the line of its development for the production of such 

 crops as potatoes, cabbages, and the later truck crops, including sugar 

 corn and green peas for canning purposes rather than its development 

 for the earlier and lighter truck crops. 



The amount of organic matter in the surface soil, either under nat- 

 ural conditions or after a considerable period of tillage, is too low 

 to constitute the Knox silt loam a first-class corn soil, especially if it 

 be compared with such types, occurring in the same general region, as 

 the Marshall silt loam or the Carrington loam. In addition, its dense 

 subsoil frequentty interferes with the deep penetration of the corn 

 roots and tends to diminish the yield because of drought conditions 

 frequently to be encountered in the latter part of the growing season 

 of the corn. It is thus better suited to the small grains than to corn 

 or to special crops. 



Locally, even winter wheat is injured and the yields of this crop 

 are reduced through lack of surface and subsoil drainage in depressed 

 or unusually level areas of the type. 



In all of the more steeply sloping portions of the type, and these 

 comprise practically its entire development in several of the areas 

 where it has been encountered, difficulties arising from the rapid 

 erosion of the soil make it inadvisable to raise either corn or the 

 small grains upon it or even to grow grass to be cut for hay. 



In the more southern regions where the Knox silt loam occurs, par- 

 ticularly along the Ohio River in Indiana and Kentucky, the climate 

 is somewhat too warm to admit of the best results in corn growing 

 upon this type. As a consequence this crop becomes subordinate to 

 winter wheat, although considerable areas of corn are grown. In 

 the same region oats practically vanish from the cropping system and 

 winter wheat is the only universal small grain crop grown. From 

 this condition there is a gradual change northward to those Iowa and 

 Wisconsin areas in which the Knox silt loam is encountered, where 

 corn is an important crop, though subordinate in acreage to oats and 

 grass in many localities. In these more northern regions winter wheat 

 is grown to only a very limited extent and oats constitute the chief 

 cereal crop. Like variation in crop production upon the Knox silt 

 loam is experienced from east to west until the Missouri Iviver is 

 passed. In Nebraska, however, corn again becomes the preeminent 



