TRRTGATIOX EX I'KHI M KXTS IN IDAHO. 



27 



por acre from the land and a low return per acre-foot of water de- 

 pends mi the relative cost of land and water, the cost of production, 

 and other factors. The solution of the problem in each instance 

 depends on local economic conditions. 



The curves presented in figure 7 show the average results secured 

 from 21 plots of alfalfa grown during five years at the Gooding ex- 

 periment station, and also of three plots grown at Buhl, 30 miles 

 away, on the same type of soil. These curves show that alfalfa re- 

 quires large quantities of water and that the yield increases as the 



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ml 



m m 



V 



H fl 



I ft 



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 J| 





1 s 





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■ 



■ I 



B B E 





m B 



1 



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1 



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fill: 



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tarn 









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*13 







Fig. 6. — Effect of different amounts of water on the yield of straw. Gooding experiment station. 



supply of water is increased, sufficient water not having been ap- 

 plied to determine at what point the excessive supply begins to de- 

 crease the yield of alfalfa. The lower curve shows yields of hay per 

 acre-foot of water applied and indicates that while less efficiency is 

 secured from water where large applications are made, the decrease 

 is not nearly so pronounced as when they are applied to grain. These 

 curves and the data from which they were constructed are typical of 

 the results secured throughout other districts of Idaho on this same 

 type of soil and show that if yield alone is considered it is difficult to 

 apply too much water to alfalfa, provided no more is applied at one 

 time than will be promptly absorbed by the soil. The proper 

 quantity to allow for alfalfa, however, as with the grains, will be 

 determined bv local economic conditions. 



