172 



LEGUMINOUS CROPS 



Much care must be exercised in having the seed perfectly clean 

 and free from weed seed. 



Alfalfa is not a good crop to fight weeds. One of the most 

 common causes of failure with this crop is that the field becomes 

 infested with weeds within a few years after planting. For this 

 reason, it is probably more important to have pure seed than with 

 almost any other farm crop. The seed should be secured from 

 regions where the fields are as free from weeds as possible, and 

 before planting the seed should be run through a fanning mill 

 cleaner and thus freed from many of its impurities. 



Fia. 118. The seeds of dodder (shown above) are smaller than the seeds of alfalfa, and may 

 be separated by properly sifting them. (Productive Farm Crops.) 



There are several varieties or strains of alfalfa. The Grimm 

 is the hardiest variety and the best for northern regions. Other 

 strains are not so well established. Some of these are of trailing 

 habit, and thus better suited to pasture than the more upright 

 forms. The alfalfas also vary in their root systems from the long 

 deep tap roots to the spreading roots. Some have a jointed root- 

 stalk which sets up growth from the nodes or joints. Most of 

 these forms are not well distinguished, and the seed of distinct 

 varieties is difficult to obtain. Dealers handle seed from Tur- 

 kestan under that name. The Grimm variety is also found in the 

 market. Most of the seed sown in America is of the so-called 



