LEGUMES FOR SEED 



271 



335. Adaptation. The soy bean has a soil adaptation similar 

 to that of the common field bean, and a climatic range and 

 adaptation similar to that of maize. In general, the soy bean 

 finds its best adaptation south of the climatic range of field 

 beans and north of 

 that of the cowpea. It 

 is less easily injured 

 by frost, and can en- 

 dure dry weather bet- 

 ter than the field bean. 

 Soy beans will grow, 

 however, on soils too 

 sandy and poor for 

 field beans, and are 

 adapted to the im- ~ 

 provement of such soils 

 when properly inocu- 

 lated. At the Vermont 

 Station cowpeas yield- 

 ed less than half as 

 much dry matter, and 

 less than two-thirds as 

 much protein as the 

 soy bean. 



Soy beans are char- 

 acterized by the large and abundant root-tubercles, which 

 the tap and branch roots bear when soil is properly in- 

 oculated, especially in sandy soils comparatively deficient 

 in available nitrogen, and under such circumstances are 

 characterized by the increased vigor and size of inoculated 

 compared with uninoculated plants. Practical experience has 

 shown that this plant is less likely, when introduced into a new 

 region, to find in the soil the proper organisms for the forma- 

 tion of root-tubercles. The inoculation of the soil with soy 



Root tubercles on soy bean 

 (After Moore) 



