IRRIGATION AND SEWAGE FARMS 139 



best are those that are commonly grown in the neighbour- 

 hood. 

 I At Berlin, before reaching the grass plots, the sludge is 

 1 removed by catch-pits, as a coating of sludge interferes with 

 1 the growth. For cereals and seeds unstrained sewage is only 

 applied while the crops are underground, so that it does not 

 come in direct contact with the plant, but roots and gr^ss are 

 irrigated all the year round. The farms have an area one and 

 a half times that of the city, and lie about six to ten miles 

 distant. The surface is divided into level beds 150 to 200 feet 

 square, separated by distributing embankments and ditches, 



Iwith underdrains 4 to 6 feet deep and 16 to 30 feet apart, 

 according to the nature of the ground. The effluents, which 

 are clear and without odour, are collected by main channels 

 and carried to the nearest watercourse. The sewage is admitted 

 to the carriers from the forcing mains through checking 

 chambers, made of woven willow and posts driven into the 

 sand; thence it passes through wooden sluices to the beds. 

 Average amount dealt with : 6 to 7^^ million gallons per acre 

 per annum, or i acre to 750 people. The best paying crop is 

 rye grass, of which six to seven crops are raised each year ; 

 turnips, beet, cabbage, and other water-absorbing plants are 

 raised in larger quantities. The farms are said to yield a 

 small profit over the working expenses, excluding the cost of 

 pumping. 



At Brighouse, Yorkshire, it was reported in 1903 that the 

 sewage, treated with 18 grains per gallon of lime and sedimented, 

 gives good crops of rye grass and mangolds, and that cabbages 

 make an excellent crop providing no stagnant water is allowed 

 to remain about the plants. The sludge is used freely, and is 

 found to be a good manure on the lands at present not irrigated, 

 and is taken by farmers. The provision for land and works was 

 unusually liberal, and had cost ;£'ioo,ooo. 



Details of a number of sewage farms are given in the Fourth 

 Report of the Royal Commission on Sewage, 1904. 



Analyses of drainage from land receiving raw and chemically 

 treated sewage show that nitrification takes place more rapidly 

 with the latter, as the felting of the solids on the surface 

 preyentsair from passing into the soil for oxidation when 

 untreated sewage is passed directly on the land.^ 



^ For an interesting example vide Ashton, "Treatment of Wigan Sewage," 

 Transactions of the Institute of Sanitary Engineers, November, 1899 ; see also 

 pp. 147 and 159. 



