1917] 



KUEAL ENGINEERING. 

 Results of studies of alfalfa irrigation practices. 



687 



The general conclusion drawn is that " from 2.5 to 3 acre-feet of irrigation 

 water per acre per year is sufficient for the growth of maximum economic 

 yields of alfalfa on the medium loam soils of Sacramento Valley." 



Irrigation and drainage, E. Risler and G. Weky {Irrigations et Drainages. 

 Paris: J. B. Bailliire d Sons, 1916, 3. ed., rev. and enl., pp. 566, figs. 186). — 

 This is the third revised and enlarged edition (E. S. R., 15, p. 934) of one of 

 the volumes of the Encyclopedie Agricole. 



Part 1, on water plants and the soil, contains chapters on the physical and 

 chemical relations between water, soil, and plants ; the regime of water in 

 geological formations ; and fertilizing substances. Part 2, on irrigation, contains 

 chapters on effects of irrigation ; quality, methods of obtaining, and distribution 

 of irrigation water ; cost, technique, assessments, practice, and economics of 

 irrigation ; irrigation ditches and canals ; duty of water ; drainage of irrigated 

 lands ; irrigation in mountain regions ; silting ; maintenance of prairie irrigation 

 systems and prairie irrigation practice. Part 3, on drainage, contains chapters 

 on the origin, indications, and bad results of excess of water in soil ; reclamation 

 and drainage and methods therefor ; definition and history of drainage ; theory, 

 execution, and results of drainage ; obstructions of drains and methods of pre- 

 vention ; drainage economics ; and types of drains and their proper use. 



Drainage of irrigated farms, R. A. Hart {U. S. Dept. Agr., Farmers' Bui. 

 805 {1911), pp. SI, figs. 19). — This describes methods of draining irrigated 

 farms. See also a technical report by the author (E. S. R., 33, p. 88). 



Standard specifications for drain tile {Amer. Soc. Testing Materials, A. S. 

 T. M. Standards, 1916, pp. 452-468, pi. 1, figs. .^).— Specifications for farm, 

 standard, and extra quality drain tile are given as issued for 1916. 



The quality of water and confirmatory tests for Bacillus coli, A. Wolman 

 {Jour. Amer. Water Works Assoc.. 4 {1917), No. 2, pp. 200-205, fig. i).— Experi- 

 mental data are reported from which it is concluded that " a water showing the 

 highest degree of actual pollution, as determined by the highest percentage of 

 samples giving a positive isolation test for colon, in general gives the highest 

 percentage of presumptive tests confirmed. A water showing the lowest degree 

 of actual pollution in general gives the lowest percentage of presumptive tests 

 confirmed. . . . 



"A rough quantitative test for pollution, in a general study of a water, might 

 with safety consist only of a determination of the presumptive tests confirmed, 

 rather than of a detailed estimate of the percentage of samples showing isola- 

 tion tests in varying dilutions. In such a procedure one might establish as bases 

 for comparison a maximum and minimum percentage of tubes confirmed, using 

 for this purpose waters grossly polluted in the first case, and unquestionably 



