LEGUMES 



211 



273. The soils suited to alfalfa. Alfalfa is very sensitive to 

 acid in the soil ; therefore it cannot be grown upon a soil that 

 is not at least neutral, and the soil should be distinctly alkaline. 

 A stand of alfalfa soon perishes under conditions which are not 

 favorable for the devel- 

 opment of the bacteria 



that gather nitrogen 

 from the air. It is a 

 deep-rooted plant, and 

 on that account must 

 have a deep soil (Fig. 

 99). Alfalfa produces 

 enormous yields, and 

 therefore must have a 

 soil that contains suffi- 

 cient nourishment for 

 the plants and, particu- 

 larly, enough water to 

 sustain a large growth. 

 Hence a loamy soil, 

 drained and aired to 

 considerable depth, is 

 required. Soils which 

 are very light or sandy 

 are not the best soils 

 for alfalfa, since they 

 are likely to be low in 

 fertility, though this 

 may be largely over- 

 come through the use 

 of an abundance of 

 manure. Compact clay 

 soils or soils underlaid with hardpan are not good for alfalfa. 



274. Manure and lime. Before the young alfalfa plant has 

 established its root system so as to give it a large feeding area, 

 and before the bacteria have developed in sufficient numbers to 



FIG. 99. Crown and roots of alfalfa 



This is an old alfalfa plant, and its roots had pene- 

 trated so deeply into the soil that in removing the 

 plant only the few large roots were secured 



