282 EXPERIMENT STATION RECORD. 



are used to give the average depth, the total discharge is determined with an 

 average error of about 6 per cent. Errors in individual experiments were much 

 higher." 



See also a previous note by Scobey (E. S. R.. 31, p. 288). 



[Irrigation investigations in California] (California Sta. Rpt. 1915, pp. 

 llf-ll). — Irrigation investigations made in cooperation with the Office of Experi- 

 ment Stations of the U. S. Department of Agriculture and with the California 

 State Department of Engineering under the direction of F. Adams are reported. 

 Experiments on the economical use of irrigation water by F. Adams and R. D. 

 Robertson on about 70 Sacramento Valley farms showed that " on the average 

 the same rule of diminishing yield and diminishing profits, where more than 

 30 acre-inches of irrigation water have been applied to alfalfa, holds equally 

 on those farms, although, of course, the economical duty of water for alfalfa 

 on very open and very tight clay soils differs considerably. The depth applied 

 annually on the 70 farms has varied from 1.04 to 9.59 ft. On one farm, where 

 the application was 9.59 acre-feet per acre, the yield of alfalfa was only 5.84 

 tons per acre and on another, where the application was 1.04 acre-feet, the 

 yield was 7.17 tons per acre. In the former case the soil was underlaid with 

 coarse gravel, whereas in the latter case it was a silt loam." 



Duty-of-water studies on alfalfa soils by F. Adams, S. H. Beckett, and O. W. 

 Israelsen, during which more than 18,(XX) soil-moisture determinations were 

 made, showed that in one case " the amount of water applied at each irriga- 

 tion was nearly five times the calculated water capacity of the first 6 ft. of 

 soil and nearly five times the quantity retained." In another ca.se desirable 

 practice was illustrated in that " the calculated water capacity, the quantity 

 applied, and the quantity retained were very nearly equal." On most hard 

 soils studied " it was impossible to get into the .soil more than about one-third 

 of the amount tlie first 6 ft. could absorb. . . . 



"It is obvious from these results that It Is not economical to apply 2 acre- 

 feet of water at an irrigation when 0.5 acre-foot is all the upper 6 ft. of soil 

 will retain. It is equally obvious that a type of practice that fails to put irriga- 

 tion water into the soil where the crop can utilize it Is faulty." 



Irrigation, of rice on the coastal prairies of Texas, C. G. Haskell (Texas 

 Dept. Ayr. Bui. 43, pp. 88-116, figs. 5).— This paper deals with the methods 

 develope<l for the Irrigation of rice in southeast Texas. 



The soils of the locality consist of sandy loam, loam, and heavy black clay, 

 with an Impervious subsoil near the surface, and are considenMl to be well 

 suited for rice growing. A good supply of fresh water is considered es.sentlal 

 for rice Irrigation, and 99.8 per cent of the water usetl Is pumpetl. The pump- 

 ing machinery generally is designed to provWle 1 cu. ft. of water per minute 

 per acre of land Irrigated, the lift varying from 10 to 80 ft. Fourteen years' 

 study of the duty of water for rice Irrigation Indicated that, allowing time for 

 a breakdown of the pumping plant and for the stopping of pumping during 

 or after rains, the duty of water for rice irrigation for prairie land Irrigated 

 from canals varies from 7.5 to 8 gal. per minute per acre, depending upon 

 the character of the land and the distance the water Is conveyetl. For the black 

 clay loam or loam alluvial .soils along the rivers 10 gal. of water per minute 

 per acre Is considered necessary, while land with a loose subsoil near a river 

 or lake may require .38 to 40 gal. per minute per acre. Petroleum has been 

 found to be the best fuel for pumping plants within short distances of tlie oil 

 fields. 



The irrigation canals are built on the highest ground and consist of two 

 parallel levees built on the surface of the ground 50 to 200 ft. apart with 

 laterals or smaller canals branching from the main canals to reach land on 



