OFFICE OF EXPERIMENT STATIONS. 759 



in the arid region is the use of water, and the primary purpose of all 

 demonstration work in this region should be showing the settler how 

 to use water. Some of the state experiment stations have established 

 substations in newly irrigated sections for the purpose of experiment 

 and demonstration, and this Office is cooperating in the operation of 

 these stations, notably in California, Washington, Utah, and Idaho. 

 This work might be extended to advantage, making the main feature 

 at each farui the illustration of methods of using water. 



While the most pressing agricultural need of the arid region just 

 now is for practical directions regardiug the use of water for the 

 incoming settler, ultimately the greatest need will be a more econom- 

 ical use of the limited water supply. For this reason much attention 

 is being given to the studv of methods of preventing the enormous 

 losses of water which previous investigations have shown to exist. 

 These measurements have shown that Avater is lost by percolation and 

 evaporation from the point of its diversion into canals until its final 

 dissipation after being applied to fields, the total of these losses 

 equaling from one-half to three-fourths of the quantities diverted. 

 The checking of these losses oifers the greatest opportunity for the 

 future extension of the irrigated area in the United States, since the 

 total water supply will reclaim only a small part of the available land 

 of the arid region. 



The greatest losses arise from seepage from earthen canals, and 

 this Office is carrying on experiments to determine the cost and 

 effectiveness of different canal linings and methods of treating the 

 bottoms and sides of canals to lessen seepage. 



It is possible to prevent seepage by lining canals with cement, 

 plaster, or concrete, but the cost is often too great for the crops grown 

 in many sections, and the real problem is to check the losses at a cost 

 Avhich can be repaid from the crops grown. Every saving effected 

 is equivalent to a new supply of an equal volume, with the added ad- 

 vantage that the water saved would not only have been lost, but 

 would have injured the lands into which it seeped. 



Further losses occur when the water is applied to the soil, due to 

 evaporation into the air and percolation into the subsoil beyond the 

 reacli of plant roots. That these losses are large and that they are 

 checked by applying Avater in such a way that the top soil is not satu- 

 rated and by cultivation after irrigation has been a matter of common 

 knowledge for many years, but there has been no exact knowledge as 

 to the extent of the losses or the effectiveness of the means adopted 

 to check them. Experiments to determine these questions w^ere begun 

 by this Office, in cooperation with the State of California, in 100.5, 

 and have been continued since that time. The results from these ex- 

 periments were so good that it seemed best to extend the experiments 

 to other places with different soil and climatic conditions, and conse- 

 quently, in the season of 1908. the necessary equipment was installed 

 at Reno, Nev. ; Bozeman, Mont.; Agricultural College, N. Mex. ; 

 and Kennewick, AVash.; and in the spring of 11)01) at Williston, 

 N. Dak., aud Caldwell, Idaho. Similar experiments in applying 

 water by different methods and following irrigation by different de- 

 grees of cultivation were carried on simultaneously at these points 

 during the season of 1909, and are being continued in 1910. The 

 principal value of these experiments will be in giving exact knowl- 



