786 EXPERIMENT STATION RECOED. 



how much water each crop can stand, and to preserve the proper balance 

 between the raising of crops and the disposal of the water often requires con- 

 siderable skill and experience. Usually in wet weather, when the crops need 

 the least added water, the sewage flow is the greatest, hence its disposal at 

 such seasons is more difficult. . . . 



" Corn and forage crops are raised and sometimes fruit and vegetables. . . . 

 Berries, salad greens, celery, and low-growing fruits and vegetables, which are 

 eaten raw, should not be raised. . . . 



"Extended sewage areas often have a direct effect upon neighboring wells. 

 Such wells should be frequently examined, and in the location of new works the 

 wells in the vicinity should be considered." 



Treat Illinois sewag'e with activated sludge {Engin. Rec, 71 {1915), No. 14, 

 pp. 421, 422, figs. 4). — Experiments on the treatment of sewage by the activated 

 sludge principle showed a marked reduction in the time required for complete 

 nitrification as compared with the time required when simple aeration was em- 

 ployed. With straight aeration this time varied from 15 to 33 days, while when 

 the sludge was added complete nitrification was affected in only four days and 

 the reduction in the amount of air used was from 4,830 to 1,270 cu. ft. 



Analyses of the sludge showed that the dried material contained 6.3 per cent 

 nitrogen, 1.44 per cent phosphorus, and 75 per cent volatile matter. It is con- 

 sidered valuable as a fertilizer. Pot culture experiments using the sludge and 

 dried blood showed better growths for the sludge at the end of 18 days than 

 for the dried blood and far better growth than on the unfertilized pot. 



See also previous note by Ardern and Lockett (E. S. R., 32, p. 387). 



RURAL ECONOMICS. 



Early economic conditions and the development of agriculture in Min- 

 nesota, E. V. Robinson {Univ. Minn., Studies Soc. Sci., No. 3 {1915), pp. 

 V-\-S06, figs. 221). — This study outlines in great detail the agricultural develop- 

 ment of Minnesota. After describing the physical features, climate, early travel, 

 trade, and transportation, and the development of pioneer agriculture prior to 

 1860, the author traces the changes in agricultural conditions by ten-year 

 periods from 1860 to the present time. The transition from the specialized 

 wheat farming to diversified farming, with its accompanying causes and effects, 

 is given. 



The text is accompanied by a large number of maps and diagrams and statis- 

 tical tables. The appendix contains an extensive bibliography. 



Social and economic survey of a community in northeastern Minnesota, 

 G. P. Wakbeb {Univ. Minn. Current Problems No. 5 {1915), pp. VI-\-116, figs. 

 35). — This report is based upon a study of the town of Braham, Minn., and 

 the surrounding territory. Among other things, the author concludes that "a 

 good producers' association would help to get much larger returns, even if the 

 marKeting were left to the present competing jobbing concerns. 



"The farmers of the community should discuss regularly in club meetings 

 methods of improving farming and marketing conditions. There is plenty of 

 local talent to conduct these meetings with programs of the proper kind." 



He points out that the "county ditches" have done much to drain this coun- 

 try, and have accomplished the first thing necessary in the construction of good 

 roads, but it is necessary to go slowly in improving the roads because the kind 

 and amount of traffic the farmers have to do does not warrant inordinate ex- 

 penses, such as is entailed in the construction of macadam and concrete roads. 



"Owing to the gi'adual change wrought by newcomers of different nationali- 

 ties, and the dissemination of socialistic doctrines with their usual agnostic 



