Sewage- Farming. 
399 
or should possess the capacity of being laid in some such form. 
There are not wanting, indeed, advocates for rather steep hill- 
sides, so that the sewage can be used two or three times over, 
after the fashion of catch water meadows ; but this mode of 
irrigation with sewage is found both expensive and troublesome, 
the cultivation of the land being rendered far more difficult. 
With proper management, there should be no difficulty in ex- 
tracting from the sewage, on its first application, nearly the 
whole of its manurial properties, and if this result is unaccom- 
plished it must be from some fault in the cultivator or some 
deficiency in the filtering powers of the soil. To secure this 
most necessary object, the farmer should see that his land is laid 
out in the manner which modern experience has proved the best. 
The quality of the land selected is a point of somewhat less 
importance, provided that it be not too stony or gravelly for 
perfect filtration, and not too stiff^ for easy cultivation. This 
latter description of land has, indeed, received the sanction of a 
high authority, Mr. Bailey Denton ; but notwithstanding the great 
weight of his opinion, I may be allowed to doubt whether the 
theoretical advantages which clays unquestionably possess, for the 
retention of certain valuable elements in sewage, would not be 
far outweighed by the impediments to their tillage which would 
be offered by their other qualities. A heartbreaking and pro- 
fitless task would seem to be laid upon the man who should 
undertake the cultivation of stiff clay under sewage. A poor 
sand, or not too porous gravel, would probably in the long run 
answer the purpose of the sewage-farmer better than a naturally 
richer soil at a greatly enhanced price. There already exists 
sufficient evidence that the poorest sand will afford an ample 
return for his outlay. At Aldershot he will find almost pure 
silica, with a mixture of actually poisonous peroxide of iron, 
successfully irrigated and cropped. At Barking and Romford, 
plots of the most sterile gravel have yielded unexpected returns ; 
but the farmer will avoid such extremes as these by choice. He 
should, moreover, take care that the land he selects possesses quali- 
ties for the purification of sewage, and also for the utilization of its 
fertilizing ingredients. As a matter of fact, some soils possess 
one of these qualifications without the other. It should be the 
province of the town authorities to select soil suitable for the 
former purpose, whilst the latter must not be lost sight of by 
the sewage-farmer in his estimate of its value for his end. The 
Rivers Pollution Commissioners found that certain soils pos- 
sessed in far greater degree than others the property of nitrifi- 
cation, i. e., the conversion of ammonia and organic animal 
matter into nitrates ; indeed this process hardly goes on at all 
in some soils. When 3"8 gallons were filtered per diem through 
