Toicn Seivage. 479 



gen is, on the other hand, higher than in sewage. Of potash, the 

 proportion is lower in the (p-ain, the only part of the crop which 

 is, as a rule, sold off the land. 



After a seasonable word of caution about drawing practical 

 conclusions from what may, at first sight, appear the obvious 

 indications of the figures in the Table, these conclusions are 

 drawn : — 



That if sewage alone be applied constantly to meadow-land, 

 potash would be more likely to fail than phosphoric acid; but 

 for the ordinary crops of a rotation, the phosphoric acid would 

 rather be in defect. In any case, the balance might easily be set 

 right by supplies from other sources. 



The composition of the manurial constituents in sewage is, 

 therefore, generally satisfactory. The difficulty lies in their 

 extreme dilution, and consequently the great cost of distributing 

 them 'over an area at all commensurate with that whence they 

 were derived ; * and the necessity for a continuous outlet at all 

 seasons, which cannot be afforded by crops which have to ripen 

 — a difficulty aggravated by the fact that the supply is greatest 

 in wet weather, when the land can least bear, or least requires it. 



The Practical Value op Sewage. 



This point will be illustrated by reference both to the results 

 of direct experiment, and to the judgment of practical men, who 

 have utilised sewage with a view to profit. 



The Rugby Experiments. — At Rugby two fields of meadow- 

 land were experimented upon ; in each, one plot was left without 

 sewage, one received sewage at the rate of 3000 tons, one at the 

 rate of 6000 tons, and one at the rate of 9000 tons per acre 

 per annum. The experiments were so conducted through 

 three consecutive seasons, and Table VI. summarises the results 

 obtained. (See following page.) 



The 5-acre field was much flatter than the other ; its soil and 

 subsoil were much more porous. The mechanical and chemical 

 examination of samples, taken to the depth of 9 inches, showed 

 its soil to be much more stony, to retain much less water under 

 equal external conditions, to contain much less organic matter, 

 much less nitrogen, much less clay, and much more sand than 

 that of the 10-acre field. It was, in fact, decidedly inferior 

 in natural quality, and yielded, accordingly, considerably less 



* Mr. Eawlinson, one of the members of the Royal Sewage Commission, has 

 given it as his opinion that it would cost more to distribute 500 tons of sewage per 

 acre, by means of pipes, hydrants, and hose and jet, as would be requisite in the 

 case of application to arable land and crops generally, than to apply .5000 tons per 

 acre by means of open runs, as in the case of its application to grass. 



