CHAPTER XI 



SEWAGE IRRIGATION 



THE methods of distributing water in sewage irri- 

 gation are essentially the same as those already de- 

 scribed. The topography of the field to be watered 

 and the character of the soil or of the crop, will 

 determine which method shall be employed. It re- 

 mains here to state, from the agricultural side of the 

 subject, under what conditions sewage irrigation may 

 be practiced to advantage and what crops are best 

 suited to utilize the water. 



OBJECTS SOUGHT IN SEWAGE IRRIGATION 



There are two main objects sought in the use of sewage 

 in irrigation. The first and primary one is to oxidize and 

 render innocuous the organic matter which it contains. The 

 secondary object is to utilize this organic matter, together with 

 the water and other fertilizers which it may contain, in the 

 production of crops. Reference has already been made to this 

 point in connection with the Craigentinny Meadows, where a 

 poor soil has been made to yield a gross income of $75 to 

 more than $100 per acre per annum for nearly a century. 



The oxidation and denitrification of the organic matter borne 

 in the sewage water must be accomplished largely, if not wholly, 

 through the agency of fermenting germs, and this being true, 

 it is imperative that the methods of treatment shall be favor- 

 able to the activity of these forms of life. 



(403) 



