6 SOILS OF THE EASTERN UNITED STATES. 



main outlets is concerned, but should be undertaken as a community 

 problem. The drainage of individual farms could then be led into 

 the mains and complete drainage secured. 



It is probable that, for the main lines, open ditches should be dug. 

 Into these the larger lines of tile could empty, gathering, in turn, the 

 drainage from individual farms. 



In Illinois adequate State laws exist for the formation of drainage 

 districts. 



The chief problem in draining this type of soil will arise from the 

 dense, impervious nature of the subsoil, which will retard the perco- 

 lation of water into the tile. It is probable that the tile should be 

 laid at depths ranging from 3 to 4 feet below the surface, and even 

 then the frequency of tile lines will need to be carefully adjusted 

 to accomplish complete drainage. Although the prairie is apparently 

 nearly level, there are few areas which do not possess sufficient 

 gradient to allow of the proper fall in the open ditch and tile lines. 



In the absence of any definite data, it would be almost impossible 

 to estimate the acreage cost for the installation of complete drainage 

 for the Marion silt loam. Areas of the dark prairies of the northern 

 part of Illinois have been drained at an average cost ranging from 

 $12 or $15 for the more simple cases to $25 per acre or more where 

 greater difficulties have been encountered. In these instances the 

 original cost of drainage has been repaid many times over by the 

 increased yields of crops and by the far greater certainty of produc- 

 ing a paying crop each year. In the case of the Marion silt loam an 

 additional advantage would be secured in that drainage is almost 

 absolutely essential to the production of corn. The extensive apple 

 orchards upon the type would also benefit to a very great degree by 

 the improvement of drainage conditions. 



Next to improved drainage, which is a community problem, the 

 increase of the organic matter content of the surface soil is one of the 

 most essential improvements to be accomplished in the tillage of this 

 type. For this purpose the growing of leguminous crops is to be 

 recommended. Clover does fairly well upon the better-drained areas 

 of the Marion silt loam, and cowpeas can be grown upon a consider- 

 able proportion of the type. For the profitable growing of either 

 of these crops, either as forage crops or for the purposes of green 

 manuring, the land should be limed. Applications of finely ground 

 limestone rock at the rate of 2 to 4 tons per acre, or where lime rock 

 is not available, the use of the burned stone lime at the rate of 

 about 1 ton per acre, are recommended for this purpose. If clover can 

 be grown upon any particular farm it may be seeded with the winter 

 wheat, cut for one year as a hay crop and the early growth of the 

 second year turned under as a green manure. Cowpeas should be 

 grown as a forage crop and may also be grown specifically as a green 



