6 SOILS OF THE EASTERN UNITED STATES. 



drainage, this condition of poor drainage was rapidly removed. 

 The land thus reclaimed was found to be even more productive than 

 the timbered lands previously occupied. The cost of artificial 

 drainage was usually low, since the ditches were easily dug in the 

 stone-free soil and subsoil and in the majority of instances only a 

 single line of tile laid through some depression or broader slough 

 was necessary to remove the surplus water which had previously 

 prevented crop production. The tile drainage of this type and of 

 similar soil types in Ohio, Indiana, and Illinois has been accom- 

 plished through the laying of thousands of miles of drains at a 

 cost estimated in various cases from $10 to $12 or $15 per acre of the 

 land drained, on the average, with maximum costs not much exceed- 

 ing $20 per acre. When it is considered that these very moderate 

 expenditures have sufficed to bring under the most profitable cultiva- 

 tion millions of acres of land of the highest agricultural value, it 

 will readily be seen that the drainage of this type has been one of the 

 great engineering problems worked out by the American farmer for 

 the betterment of his lands. Such drainage operations have not 

 been required to any extent in areas of the type found west of the 

 Missouri River. However, there still remain considerable areas of 

 but partially drained land included within the Marshall silt loam in 

 northern Missouri and portions of Iowa. Even where water does 

 not stand through any portion of the year upon the surface soil, it is 

 frequently the case that the installation of a moderate number of 

 tile drains over fields occupied by this type wdll increase the depth 

 of friable surface soil material, render the zone occupied by tlie roots 

 of crops considerably deeper, and accomplish the certain production 

 of excellent yields, both hi seasons abnormally wet or unusually dry. 

 Especially in such instances, which are rare, where small areas of 

 "hardpan" are found between the surface soil and the subsoil is 

 additional drainage to be recommended. 



West of the Missouri River the higher elevation and somewhat 

 steeper slopes found within the areas of the Marshall silt loam not 

 infrequently give rise to incipient or even serious erosion along the 

 margins of the type. Where this is the case, it is to be recommended 

 that such steep areas should be established in permanent pasture 

 grasses, and the areas should be used for the maintenance and 

 grazing of beef cattle and dairy cows. The area of this type subject 

 to destructive erosion constitutes but a very small percentage of its 

 total extent. 



LIMITATIONS OF YIELD. 



The surface soil of the Marshall silt loam is so friable, so free from 

 stone, so well granulated, and so nearly level that all of the crops 

 suited to the climate and to a silty soil are grown to perfection upon 

 it. The surface soil readily absorbs by far the greater proportion 



