TYPES OF DRAINS 



171 



connection to determine the approximate concentration 

 of total soluble salts. For exact work, chemical methods 

 should be resorted to, but for general reconnoissance 

 work the bridge can be used to advantage. 



Types of Drains. After deciding that the land needs 

 drainage, the next point to settle is the type of system to 



FIG. 21. BOGGY ALKALI LAND THAT is 

 WITH SHORT TILE. 



TO DRAIN 



install. No one system is best for all conditions. On 

 some projects a combination of systems can be used to 

 advantage. 



The open drain on account of its low initial cost has 

 been used rather extensively. It has some advantages 

 and many disadvantages. Among its advantages is the 

 fact that its action is at all times under the observation 

 of the farmer. Any obstruction can easily be found and 

 removed. The fact that the farmer can do most of the 



