382 



IRRIGATION PRACTICE 



paradox, underdrainage on a small scale must be a 

 necessary complement of irrigation. The sooner, there- 

 fore, that underdrainage is established, in places where it 

 is necessary, the better it will be for the development of 

 the irrigated region. The low-lying, water-logged lands 

 are fertile, and, when drained, require very little irri- 

 gation. Many excellent experiments have been made on 



FIG. 111. Pumping plant. (Lifts water 37 feet and 

 irrigates 70 acres. (Montana.) 



the underdrainage of lands in the irrigated region, and 

 the practice has been found to be wholly successful and 

 in cost to be well within the farmer's reach. 



The methods for underdrainage under irrigated con- 

 ditions are only slightly different for those prevailing 

 under humid conditions. Usually an upper main drain is 

 constructed, transverse to the flow from the upper canal, 

 so as to intercept the water seeping from above. (See 

 Fig. 112.) Where the subsoil rests on a hardpan, blasting 



