IRRIGATION AND SEWAGE FARMS 149 



lIso find that the effluents from land possess a bacterial flora 

 :haracteristic of sewage, and that the microbes characteristic 

 if soil are relatively absent. 



The chief objections to land filtration have been summarized 

 LS follows : 



1. Generally the worst part of the sewage — the sludge — is / 

 lot dealt with at all. 1 



2. As crops are usually grown, their cultivation is often con- 

 jidered, by those left in charge, as more important than the I 

 mrification of the sewage, and so the latter is not fully treated ' 

 jxcept where irrigation is of advantage to the crops. 



3. Unless the land receives very careful attention, a bad 

 result is generally produced from even the best farm, and it is 

 lifficult for anyone but a highly-trained man to keep the works 

 mder proper control. 



4. There are many possibilities whereby land which has been 

 [aid out carefully may fail, even with careful working, such as 

 ;he cracking of the land, admitting crude sewage into the 

 Irains without filtration. 



5. Land of sufficient quantity or quality, and at a reasonable 

 price, is often unattainable. 



The strongest argument for sewage farms and irrigation must 

 always be the restoration to the land of the matter taken away 

 from it, without which there must be a continual impoverish- 

 ment. This aspect of the question was brought into prominent 

 notice by Sir W. Crookes.^ I point out in later chapters how, 

 under graduated bacterial purification, an effluent containing 

 practically all the nitrogen, phosphates, and other mineral 

 constituents, is obtained in a condition suitable to be returned 

 to the soil without loss, and available for plant life. 



Insistence on final land treatment is now decidedly a mistake, 

 as where a proper process is used no further purification will 

 be necessary; indeed, in many instances an originally good 

 effluent suffers deterioration by subsequent passage through 

 land, and as the sewage in passing through the filters falls 6 to 

 8 feet, the expense of pumping may have to be added. At 

 Newcastle-under-Lyme in September, 1901, the Local Govern- 

 ment Board sanctioned a loan for a scheme of disposal by 

 bacterial treatment, and consented, for the first time, to waive 

 their usual requirements with respect to land treatment for the 

 filtered effluent, having regard to the limited area and unsuit- 

 able nature of the land available. 



1 BritisJi Association Reports, 1898. 



