SEWAGE FARMING. The utilization of sewage in the growth of field, orchard, and gar den crops. The most noted farms are at Paris, Berlin, Danzig, Breslau, and Birmingham, in Europe, and at Pullman, Ill., Los Angeles, Cal., South Framingham, Mass., and Plainfield, N. J., in the United States. Sewage farming. which is largely a development of the last third of the nine teenth century, is an attempt to combine crop growing with sewage purification. Where intelli gently managed a high degree of purification is attained without creating a nuisance in the neigh borhood, and the excellent crops which are grown may be used without menace to health in spite of popular prejudice to the contrary. Aside from the irrigation value of the water, sewage is of some importance agriculturally on account of the fertilizing elements it contains. Analyses show that less than 2 parts in 1000 of average sewage is solid matter, and that a ton of sewage contains from 0.15 to 0.25 pound of nitrogen, from 0.045 to 0.065 pound of phosphoric acid, and from 0.025 to 0.040 pound of potash. These would have a cash value of to 5 cents. Since, however, in actual operation much of the nitrogen is lost, the real value of sewage will not exceed 3 cents per ton and one to two cents per ton is more nearly its true manurial value. The recognized greater agricultural value of sewage over river water for irrigation is accountable for the 25 to 50 per cent. increase in rent per acre for land irrigated with sewage. Unless care he taken to prevent the sew age from coming in direct contact with crops in tended for consumption in the raw state, the methods of applying sewage do not differ from those of irrigation (q.v.). Sewage farms are lo
cated preferably on open soils with a sandy or gravelly subsoil. Clay soils are less satisfactory.
Since experience indicates that the best crops are secured when the sewage is applied only as needed, arrangements should be made for the dis posal of surplus sewage that may accumulate when the crops cannot use it. This is usually done by making separate filtration areas or by growing crops capable of withstanding large quan tities of water, such as Italian rye grass, orchard grass, perennial rye grass, and blue grass. With a controllable supply of water practically all crops suitable for the climate can be grown to perfection. In Southern California orchards are very successfully irrigated with sewage. From the standpoint of sewage disposal the primary object of sewage irrigation is to purify the sew age so that it may not contaminate the under ground water or streams. Experience on sew age farms, both in Europe and America, shows that every essential requirement of sewage puri fication is present in sewage farming, and that when sewage is rightfully used the water flowing from these farms is clear and sparkling.
Consult: United States Geological Survey Wa ter Supply and Irrigation Papers Nos. 3 and 22 on Sewage Irrigation (1897, 1899) ; Rafter and Baker, Sewage Disposal in the United States (New York, 1S94) ; Waring, Modern Methods of Sewage. Disposal (ib., 1S94) ; Kiersted, Sewage Disposal (ib., 1S94) ; Birmingham Sewage In quiry Report, 1871.