DRAINAGE 



69 



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farm crops, depending upon the conditions and the thorough- 

 ness of drainage desired. 



Systems of Tile Lines. There are several general systems 

 of arranging tile lines, each 

 of which is adapted to cer- 

 tain conditions. A descrip- 

 tion of the various systems 

 follows. 



The natural system con- 

 sists in laying tile in natural 

 depressions, or it is an at- 

 tempt to drain the soil 

 needing drainage most. 



The grouping system is 

 used where sloughs or basins 

 are encountered as well as 

 dry land little in need of 



drainage. The grouping system consists of mains running 

 into the sloughs with systems of drainage to thoroughly 



cover the area of the soil 

 needing drainage. 



The gridiron system is 

 used where complete drain- 

 age is desired, as on very flat 

 fields. The laterals are 

 placed parallel, and every 

 part of the entire area is 

 within a certain distance 

 of from the tile line. At the 

 end of the parallel laterals, 

 mains or submains of larger tile are laid to collect the dis- 

 charge from as many as possible. 



Nah/ral System 



45. The natural system 

 laying out tile drains. 



Fig. 



46. The grouping system 

 laying out tile drains. 



