278 IRRIGATION PRACTICE 



brought under irrigation. The conditions determining the 

 production of alfalfa seed are not well understood, but the 

 chief secret seems to be the use of little water. The first 

 cutting is harvested as usual for hay; the second cutting 

 is allowed to go to seed with little irrigation none if the 

 first cutting has been well irrigated; after the harvest, 

 water is added to obtain, if possible, a small third crop. 

 The use of much water diminishes the yield of seed, and 

 also retards the production of the seed until too late in 

 the fall. Morgan, working in Utah, obtained the highest 

 yield of seed when about 8 inches were used. Either less 

 or more resulted in smaller yields of seed. In other locali- 

 ties, some other quantity might be found to be best, but 

 it is never large. Another method of producing alfalfa 

 seed is to clip the first growth of alfalfa about the time 

 of the first irrigation, or a little earlier, and then to allow 

 the first crop to go to seed. By many, this is held to be 

 by far the most successful method of producing alfalfa 

 seed. The whole matter needs much careful experimental 

 study before definite rules can be laid down. 



171. Hay-making crops. The standard hay-making 

 crops may all be produced under irrigation. With the 

 growth of irrigation there will be an increasing demand 

 for a variety of hay-making crops. While nearly all hay- 

 making crops will thrive under irrigation, they do so with 

 varying degrees of success, depending upon their adap- 

 tability to the soil and climatic conditions of the irrigated 

 region. Usually, some years of adaptation precede the 

 best results from any crop introduced into the irrigated 

 region. 



The Utah work included studies of timothy, orchard- 

 grass, brome-grass, and Italian rye-grass, all of which 

 are typical hay-making crops. These were planted as 



