INQUIRY INTO IRRIGATION PRACTICE! -.70 



-and to the ascertainment of that amount, by local experience of 

 himself and others, the grower should employ his most earnest 

 thought and his keenest insight. 



During recent years the writer has continually renewed his 

 data of the irrigation practice of California fruit growers by sys- 

 tematic inquiry and has prepared four bulletins* which have been 

 published by the Irrigation Investigations of the U. S. Department 

 of Agriculture. 



A study of local practice shows that infinite variety exists and 

 in the nature of the case must exist, and that any definite prescrip- 

 tion of the duty of water under various conditions is impossible. 

 In some cases the amount of water at each irrigation must be 

 small, as, for instance, the frequent irrigation in Sacramento and 

 Placer Counties, where the soils are shallow, over-lying bed-rock, 

 and a small amount saturates them. In other places an acre-foot 

 of water is readily absorbed and retained in the deep soil. The 

 annual rainfall also has little relation to the amount of irrigation, 

 because neither fine shallow, nor deep coarse soils, can retain the 

 volume of water which falls upon them during the rainy season. 

 Then the varying rate of evaporation, the character of the tilth, 

 etc., enter as factors and it becomes clear that he is fortunate 

 who knows how much water to use on his own place. 



It is interesting to note that results of close inquiry by the Irri- 

 gation Investigations of the U. S. Department of Agriculture to 

 ascertain the amounts of water used by measurement of 

 water running in main ditches and by estimate of the acreage 

 to which ' the water is applied, do not agree closely with 

 the growers' estimates of the amounts of water which 

 they actually use. There are of course always issues between 

 water-purveyors and water-buyers which can not be entered upon 

 in this connection. A rough conclusion from data secured from 

 the ditch flow, etc., is that from 12 to 30 acre-inches of water are 

 used annually in irrigated orchards and vineyards, according to 

 local conditions involved. It is quite clear that the amounts chiefly 

 used would not be the average but would tend toward the lower 

 figure. The details of these inquiries are found in the publications 

 on irrigation of the Office of Experiment Stations, U. S. Depart- 

 ment of Agriculture.* 



* Farmers' Bulletin, No. 116, "Irrigation in fruit growing." Farmers' Bulletin, 

 No. 138, "Irrigation in garden and field," Bulletin of Experiment Stations, No. 108, 

 "Irrigation practice among fruit growers of the Pacific coast." Annual report of 

 Irrigation and Drainage investigations, 1904, "Relation of irrigation to yield, size, 

 quality, and commercial suitability of fruits." 



* Definite citation is not made because these publications are continually appear- 

 ing with additional data on the effective use of water. The whole series should be 

 examined. 



