SCIENTIFIC LITERATURE. 



101 



ment of Agriculture have been particu- 

 larly helpful in the case of Mexican 

 species. 



AGRICULTURE. 



'The Use of Water in Irriga- 

 tion' is the title of an extensive bulle- 

 tin just issued by the U. S. Department 

 of Agriculture, under the authorship of 

 Prof. Ehvood Mead, expert in charge of 

 irrigation investigations, and C. T. 

 Johnston, assistant. It embodies the 

 results of extensive investigations con- 

 ducted last year with the assistance of 

 a number of collaborators in ten States 

 of the arid region and presents an array 

 of data on the use which is being made 

 of water under different systems of 

 management, such as has never before 

 been collected for the irrigated region 

 of this country. It constitutes a part 

 of the irrigation studies which are being 

 carried on under the U. S. Department 

 of Agriculture. 



To many readers the lavish prodigal- 

 ity which has characterized the diver- 

 sion and application of water for irri- 

 gating will come as something of a 

 surprise, when the paramount impor- 

 tance of water in developing the arid 

 country is considered. This has been 

 fostered by the fact that "the laws 

 which govern appropriations of wa- 

 ter from streams have, in most cases, 

 no relation to the actual practice of 

 irrigation and therefore fail to secure 

 either the systematic distribution or 

 best use of the available supply." 

 Ditches diverted more water than was 

 used : their owners claimed more than 

 they could divert, while decrees gave 

 appropriators titles to more water than 

 the ditches could carry and many times 

 what the highest floods could supply. 

 Little was known as to the quantity of 

 water needed to irrigate an acre of land, 

 and in the absence of such information 

 the ignorance and greed of the specu- 

 lative appropriator had its opportunity. 



In the investigations reported, farm- 

 ers whose fields were under observation 

 were instructed to use water as they had 

 hitherto been in the habit of doing. The 



result of the measurements of the water 

 used showed very forcibly the influence 

 of waste in lowering the 'duty of water' 

 and of care and skill in increasing it. 

 They confirm the conviction long held 

 by students of the subject that the 

 amount of water used in practice bears 

 no definite relation to the requirements 

 of the crop, but is subject to the whim 

 of the individual and the supply of wa- 

 ter provided by the contract with the 

 canal company. For instance, the aver- 

 age amounts of water used in different 

 part of New Mexico varied from less 

 than three feet to nearly seven feet. 

 This was independent of the rainfall. 

 In many cases the farmers using the 

 least water got quite as good crops as 

 those who used enormous quantities. 

 On some soils which were not well 

 drained there was a very marked injury 

 from excessive irrigation. In the Boise 

 Valley in Idaho it was found by meas- 

 urement that fully one-half the water 

 now diverted by canals is wasted under 

 present methods. Apart from the losses 

 from extravagant use of water, there 

 are heavy losses, under present manage- 

 ment, from evaporation and seepage 

 from the canals. The average of the 

 measurements made show the loss from 

 this source to be fully thirty per cent. 

 Mr. Mead expresses the conviction that 

 throughout the sections where measure- 

 ments were made last year it will be 

 possible, through improved methods, to 

 double the average duty of water now 

 obtained, so that the quantity now re- 

 quired for one acre will serve to irri- 

 gate two. 



The importance of this becomes more 

 strikingly apparent when it is remem- 

 bered that there is a limit to the 

 amount of land which can be reclaimed 

 with the available water supply, gen- 

 erally estimated at about seventy mil- 

 lion acres, or approximately one-fifth 

 of the arid region, and that the thou- 

 sands of miles of canals and laterals 

 thus far constructed have only re- 

 claimed an area approximately as great 

 as the State of New York. 



The results reported in this bulletin 



