416 



IRRIGATION PRACTICE 



wise use of human waste in crop-production. In these 

 countries, modern sewage systems have not been installed, 

 but the human waste is carried in specially provided re- 

 ceptacles to the farms. It is not likely that this method 

 will be adopted under civilized conditions; human waste 

 will continue to be thrown into sewage systems, but, as 

 among the Chinese and other nations that have estab- 

 lished a permanent system of agriculture, the sewage 



FIG. 121. Distribution of water on Craigentinny Meadows, Edinburgh. 



water thus produced must be used for the production of 

 crops. 



It has been argued that, for health reasons, sewage 

 should not be so used, for disease germs might be carried 

 by sewage water to the herbage and thence to domestic 

 animals and finally to human beings. The fact that sewage 

 irrigation has been practised for centuries with no evi- 

 dence of such evil effects leads to the belief that the 

 danger does not exist. Sewage, if properly applied to a 

 soil which is properly tilled, is thoroughly oxidized and 

 becomes innocuous. Plants, themselves, would not be 



