SUBIRRIGATION AND SUBSOILING. 425 



every rod or so, one foot wide and two feet deep. In 

 the bottom of this ditch a row of four-inch drain-tile is 

 laid. A line is used to keep the tile straight and true. 

 They are placed in the ditch as if they were intended 

 for draining the land. 



Six inches fall for every hundred feet is necessary. 

 The dirt is placed around the tiles by hand, until they 

 are sufficiently firm so as not to be displaced by filling 

 in with plow and shovel. If the soil is of a sandy 

 nature, it is necessary to have a piece of tin or galva- 

 nized iron over the joints, to prevent the sand from 

 filling in. The tile is placed at least eighteen inches 

 below the surface, and is out of reach of the plow. 

 The water is brought to the land by means of a pipe 

 which is laid diredlly across the tile at the highest 

 point, and a faucet is arranged so that water may be 

 turned into each line of tile at the same time. The 

 tile may be stopped at the lower end, thus allowing the 

 water to seep out of the joints until the land is suffi- 

 ciently moist. Many persons would suppose that the 

 water would descend, but it naturally rises to the sur- 

 face. It is essential that a drainage ditch should be 

 provided at the lower end of the field to serve as an 

 outlet for the tiles, which should be so arranged that 

 they can be drained during the winter, as otherwise 

 they might be cracked by the freezing of the water 

 that they would contain. Upon stiff soils with im- 

 pervious hard-pan the lines of tile can be placed con- 

 siderably deeper. 



In all subirrigation undertakings the first precau- 

 tion is to ascertain whether the stru(5lure of the soil 

 and subsoil is such that this method is prac5licable, as 



