378 FIELD CROPS 



from 1 to 3 or 4 tons to the acre. The average yield for the 

 entire country in 1909, as reported by the Census Bureau, 

 was 2.52 tons to the acre. The usual growing season for a 

 crop of hay is from thirty to' forty days, though in warm 

 weather, with plenty of rain, the field may be ready for cut- 

 ting in twenty-five days from the removal of the previous 

 crop. 



475. Soils Adapted to Alfalfa. The soils best adapted 

 to alfalfa are the deep loams, in which the roots can penetrate 

 to a considerable depth. A stiff clay subsoil which is too 

 hard for the roots to penetrate is not suitable, while sandy 



MS itfAji;' 



Fig. 117. At the left, alfalfa seed containing trash and other impurities; 

 at the right, an excellent sample of clean seed. 



land does not produce growth vigorous enough to keep down 

 weeds. On rich loams a stand of alfalfa, when well estab- 

 lished, will usually crowd out weeds of all kinds. Good 

 drainage is essential, for the plants will not grow with "wet 

 feet." Plenty of water is a necessity for the best growth of 

 the crop, but the plant must be allowed to go after it and 

 bring it up from the lower layers of the soil. 



While alfalfa will store nitrogen in the soil, it will 

 not thrive on poor land. Some nitrogen must be supplied 

 till the plants get a start and the bacteria begin their work. 



