THE WABASH SILT LOAM. 7 



of the embankment measures only 2 or 3 feet across. In all cases the 

 front of the embankment should be protected by planting rapidly 

 gro\ving trees, and the dike itself should be seeded and brought into a 

 sod condition as soon as possible after it is erected. 



In the process of such construction the earth is most frequently 

 taken from a broad, shallow ditch on the landward side of the em- 

 bankment. This ditch also serves as a main drainage channel for 

 the land included within the dike. In such cases automatic water- 

 gates are placed in the embankment which prevent the inflow of the 

 river waters at high stages, but permit the outflow of water accumu- 

 lated behind the embankment after the river recedes. One of the 

 greatest difficulties experienced in this form of embankment and 

 drainage arises in the control of small upland streams which have 

 had their normal courses through the bottom lands which are to be 

 protected. Wherever possible it is desirable to divert the courses of 

 such streams to flow into the main river at a point outside of the 

 embanked area. Lateral dikes are sometimes built along the low 

 portion of the courses of such streams to divert them from their 

 old courses. This prevents filling up the land in the diked bottoms 

 either with water or with sediments carried down from the upland. 

 In practically every case it is advisable, if not absolutely necessary, 

 to provide for a fair number of open ditches which shall lead into 

 the main ditch along the embankment, thus providing for the rapid 

 removal of rain water falling within the area. In some cases it is 

 also necessary to provide for tile underdrainage with outlets into the 

 lateral and main ditches. 



In the cases which have been under observation where lands of the 

 Wabash silt loam have been thus protected from overflow and pro- 

 vided with supplementary drainage, the resulting crop yields, almost 

 from the beginning of the enterprises, have paid a handsome return 

 upon the money expended. There is no record that the bonds of such 

 district drainage companies have ever been defaulted. Often the 

 crop yields from areas of this type thus protected are double those 

 secured from any other soils within the same areas covered by soil 

 surveys. 



There is a further limitation in the character of crops which may 

 best be grown upon the Wabash silt loam arising from the partially 

 drained condition of the subsoil materials. The type is most success- 

 fully used for corn, oats, grass, and those other general farm crops 

 planted and harvested during the same summer season. Winter 

 grain crops or long season crops are liable to suffer from drowning 

 out during the winter months or from the heaving of the land under 

 the action of fall and spring frosts. The particular adaptation of 

 this bottom land soil for the production of corn has led the majority 



