8 SOILS OF THE EASTERN UNITED STATES. 



The drainage of the Knox silt loam may usually be completed if 

 medium-sized tile are laid through the lower portions of the poorly 

 drained fields, following natural depressions and intersecting basins 

 or hollows which have no natural surface outlet. Not nearly all of 

 any single field is in need of drainage. In consequence, a material 

 increase in the crop yields of this type may frequently be secured 

 through the installation of supplementary tile drainage at a cost not 

 to exceed $10 or $12 an acre for the land affected. There are some 

 few instances where considerable areas would require the construction 

 of open ditches into which extensive systems of tile drain should 

 empty. These areas are usually indicated by an ashy-gray to almost 

 white surface soil, by the presence of iron concretions locally known 

 as "buckshot" within a foot or so of the surface, and by the light- 

 gray or obscurely mottled condition of the compact and dense subsoil. 

 Such areas, if of any extent, require complete drainage before they 

 can be cultivated to advantage to the general farm crops. 



The contrasts in slope within the area covered by the Knox silt 

 loam are sharp. Either the surface of the type is nearly level, 

 undulating, or gently rolling and capable of cultivation or, on the 

 other hand, it is hilly and steep to such a degree that no one would 

 be tempted to use it for the production of field crops. Consequently, 

 while erosion is a serious problem in many areas along the steeper 

 slopes, there is every incentive either to reestablish such slopes in 

 forest or to secure a seeding of the native or tame grasses for pastur- 

 age purposes. Wherever erosion is active around the headwaters of 

 the minor streams having their sources within this type, brush dams 

 or other obstacles should be located in the gullies to prevent the ex- 

 tension of erosion, and grass seeding should be established as rapidly 

 as possible. In no case should the intertilled crops be grown in such 

 locations, and it is advisable even to omit the small grains which 

 would require the plowing of the land and the breaking of any ex- 

 isting sod. 



In very few instances, except in the production of tobacco, is fer- 

 tilizer used to any extent upon the Knox silt loam. In some in- 

 stances the stable manures are saved and applied to this type, produc- 

 ing excellent increases in the crop yields. In other instances various 

 commercial fertilizers have been tried with some degree of success, 

 particularly in connection with wheat growing, or for the production 

 of tobacco. Usually only small amounts of commercial fertilizers 

 are applied, not over 150 to 200 pounds per acre, and these fertilizers 

 consist principally of some form of potash constituting 2 to 4 per 

 cent of the total amount, with acid phosphate as the basis for the 

 phosphoric-acid content of the fertilizer, amounting to 8 or 9 per 

 cent. Very little nitrogen is used in any of these fertilizers. The 

 amounts applied are entirely inadequate to produce any marked im- 



