358 AGRICULTURAL APPROPRIATION BILL, 1924, 



STUDY OF WATER REQUIREMENTS OF CROPS. 



One of the projects which we have under way now consists of a 

 study of tlie duty of water, or the water requirements of crops. We 

 are making; a comprehensive study of the results which have heen 

 obtained over the past 10 or 15 years, with the idea of publishing a 

 series of articles on this particular subject, which, in my judgment, 

 is the most important subject we have to deal with. A large amount 

 of unpublished data has been and is being accumulated, the publica- 

 tion of which will prove valuable to State officials in apportioning 

 the flow of streams, to courts in settling rights to the use of wat^r, 

 to engineers in determining the capacities of irrigation channels and 

 structures, to canal managers in framing water-right contracts, and 

 to farmers in growing crops. 



Another project is the percolation of water through earth dams. 

 Any loss of water through the retaining structures, if it can be avoided 

 ought to be avoided, and this project involves research in reference 

 to the best types of earthen dams to build, the kind of core walls, 

 and the pavements and drains necessary as a part of those structures. 



Another subject is the water-holding capacity of irrigated soils. 

 This subject involves a study of the movement of water downward 

 through soils and subsoils by the action of gravity and also the dis- 

 tribution of soil moisture in all directions by the action of capillarity. 



There are also studies now in progress dealing with drainage struc- 

 tures for irrigated farms. This will embrace the principles of design 

 which practice and results of experiments indicate to be the most 

 satisfactory in reducing cost and increasing efficiency of the various 

 structures used in drainage systems. 



HYDRAULIC EXPERIMENTS. 



In cooperation with some of the States we are carrving on a number 

 of hydraulic experiments, chiefly for the purpose of cleveloping instru- 

 ments for water measurement and also lor measuring evaporation. 



Mr. Anderson. Has there been an}'^ development of economical 

 piimpin"; machinery? 



Mr. McCrouy. We have made a study of the cost of pumping and 

 have also a bulletin on the subject of pumping from wells for irrigation 

 ready to submit for publication. There has been a considerable 

 increase in the efliciency of deep-well pumps in the last 10 or 1.5 years; 

 in fact, irrigating pumps generallv have mcreased in efliciency con- 

 siderably in the last 10 years. Fully 30, ()()() pumps are now supplying 

 water to more than a million acres of land, much of which is in crops 

 of yi'vy high value. We estimate that not loss than 70 per cent of the 

 irriguli'd lands of the coastal re<ijion of southern California, comprising 

 the highest priced agricultural lands of the W^est, are watered by 

 piinif)iiig plants. 



Mr. M.vcDoNAi.i). W(> have been niakin«j: a study of the cost of 

 devehming irrigated farms to the point oi ])rolital)le returns. The 

 cost of storage works, distributing systems, and other features of the 

 irrigation systems of the West, and the average cost of such con- 

 st iiut ion, as an acreage cost against the lands served are definitely 

 known. Our study is bringing out the interesting fact that the 

 original cost of placing water on the land is only a portion of the cost 

 of l)ringing that farm up to a stat(> of productivity. 



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