16 



SUUKACE- AND SI' I'.-I URNIATK >N 



SUB-IRRIGATION 



Doubtless there are soils in which sub-irrigation — watering 

 through pipes laid beneath the surface — would be more econo- 

 mical than any other method of irrigation. Theoretically it 

 appeals to the mind as being an ideal system. One writer says : 

 lt If properly carried out the system has many advantages over 

 any of those using surface irrigation. Among them may be 

 noted economy of water, as its advocates claim that it does 

 better work with less than one half the amount of water, 

 while some go so far as to claim that it saves from three fourths 



Fig. 5. Laying Tiles for Irrigation, W. Va. Univ. Gardens. 



to nine tenths. When the flooding or furrow system of irriga- 

 tion is used it will be a day's work for one man to irrigate from 

 one to five acres, but with sub-irrigation he will merely need 

 to turn on or shut off the water from the different portions of the 

 systems of tile, and while the irrigation is going on can busy 

 himself about other duties." 



The misleading feature of this system of irrigation comes 

 from the difference among the soils ; hence, unless the operator 

 has an experimental knowledge of his own conditions, his 

 chances of failure are great. A physical and mechanical 

 knowledge of the soil is necessary before one enters upon large 



