LESSON LVI 

 DRAINAGE 



Importance of drainage. Farm land should be 

 well drained in order to be highly productive. At one 

 time it was thought that drainage was useful only in 

 removing the surface water from low ground. After 

 some time the farmers realized that underdrainage is 

 valuable even on lands that have good natural drainage. 



Underdrainage. A ditch for underdrainage is 

 made by digging a trench from two to four feet deep 

 and with sufficient slope that water will readily flow 

 to lower levels. On the bottom of the trench drain 

 tiles are placed end to end to form a continuous tube, 

 and then the trench is filled with earth. The depth 

 of the ditch puts the tile beyond the reach of the plow 

 and frost and permits the draining a\vay of the ground 

 water to the proper depth. The water enters the tube 

 through the spaces between the ends of the tiles. 



Effects of drainage. Drainage not only helps the 

 crop by removing the free water from the soil, but also 

 aids it to survive a drought. In undrained land the 

 ground water lies near the surface until dry weather 

 sets in, and the root system of the crop will be confined 

 to the shallow layer of soil above the water line. If a 

 long dry period sets in, the ground water sinks to a 



253 



