THE WABASH SILT LOAM. 5 



addition, practically all areas with the exception of some of the 

 higher front lands are subject to annual overflow during the spring 

 months and may be repeatedly submerged by successive inundations 

 resulting from melting snows and spring rains continuing to about the 

 middle of June. These conditions have retarded the occupation of 

 many considerable areas of the Wabash silt loam for crop-growing 

 purposes. A good crop yield on such areas is certain only when 

 they have been protected by dikes and relieved of excess moisture 

 through the establishment of open ditches supplemented by the use 

 of tile underdrainage. Where such protection and relief have been 

 applied the wonderful fertility of the Wabash silt loam has been 

 made available for agricultural purposes for every season. In other 

 cases the land can be used only in those seasons in which the overflows 

 cease before the time for planting and tillage of the crops. Thus 

 diking and drainage constitute the most important problems in ren- 

 dering this extremely fertile soil type available for crop production. 



The erosion of the Wabash silt loam consists chiefly in the bodily 

 washing away of portions of the type along the convex sides of the 

 great curves and meanders of the streams. It is not infrequently 

 the case that at times of overflow the swift waters of the rising 

 stream cut into the soft silty banks on the outward edges of the 

 curves, removing many acres of fertile soil, which are carried away 

 and redeposited at other points farther down the stream. It is prac- 

 tically impossible to prevent or control this form of erosion in the 

 case of the larger streams, although brush dams and other forms of 

 protection are effective in the case of the smaller rivers and tributary 

 creeks. Occasionally at the height of the overflow some portion of 

 the current may be directed across the surface of this soil type into 

 some old bayou. In such instances deep cuts are rapidly formed in 

 the soft earth, and frequently new minor channels are thus opened 

 across the fields. Sometimes these are occupied for several years 

 by a sluggish current of water at the low-water stages of the river, 

 to be again abandoned and obstructed by the deposition of addi- 

 tional material across the intake of the bayou by some subsequent 

 overflow. Aside from these accidental forms of erosion there is very 

 little damage inflicted upon the Wabash silt loam by flowing water, 

 since it lies so nearly at the base level of the adjacent streams. The 

 slopes, except along the river banks, are very gentle. 



Very frequently, however, tributary streams of heavy gradient, 

 which descend from the upland, will be raised to flood level by local 

 showers, and under such conditions will carry down large quantities 

 of local material to be deposited in the form of low alluvial cones at 

 the point where the Wabash silt loam adjoins the upland slopes. The 

 rapid deposition of material under such circumstances prevents the 

 production of crops or thoroughly floods and buries those which may 



