ALFALFA 



339 



tion. A second advantage is that winter-killing from exces- 

 sive dryness of the soil is prevented. Where the winters 

 are severe, however, too great an amount of soil moisture 

 is conducive to winter-killing. 



403. Relation of yield to water supply. The actual 

 water required in irrigating alfalfa depends largely on the 

 permeability of the soil, but temperature, humidity and 

 wind are also factors of importance. Fortier states that 

 the larger number of western alfalfa fields are irrigated 

 annually with 2.5 to 4.5 feet of water, but in quite a 

 large number of cases the amount used would cover the 

 field in depths ranging from 6 to 15 feet. 



While larger yields are often obtained by using greater 

 quantities of water, such use is wasteful and apt to be 

 injurious to the land or to surrounding lands by causing 

 waterlogging and the consequent rise of alkali. 



Fortier secured the following results at the Montana 

 Experiment Station : 



The following yields are reported from the Utah Experi- 

 ment Station, using different quantities of irrigation 

 water : 



