IO2 REGLAWNG LOST NITROGEN. 



probable that there could be in the soil a different variety of bacteria 

 for every variety of legume, but rather that one kind of bacteria can 

 grow in many legumes. But the facts are not quite so simple as this. 

 Not all species of legumes are capable of developing root tubercles 

 equally well in all soils. Some soils will luxuriantly support certain 

 species of beans, peas, or clovers, producing a large crop, developing 

 quantities of tubercles and fixing an abundance of nitrogen, while 

 the same soil will not support other species of legumes with equal 

 readiness. For example, the soil of Connecticut is not adapted 

 to the legume called the soy bean. When this bean is planted in the 

 ordinary Connecticut soil it does not flourish, but yields a small 

 crop unless heavily fertilized, and does not produce tubercles. 

 This species does, however, grow readily in Massachusetts. Some 

 years ago the experiment was tried of importing Massachusetts 

 soil, upon which this plant had produced abundant tubercles, 

 and mixing it with the Connecticut soil, subsequently planting the 

 soy bean. The result was an excellent growth of the soy bean 

 and the development of tubercles. Afterward these particular 

 plots of land were capable of producing large luxuriant crops of 

 the soy bean, with abundant root tubercles and a large fixation 

 of atmospheric nitrogen. Evidently Connecticut soil does not 

 contain the bacteria adapted for producing the tubercles in the soy 

 bean, although those which produce tubercles on the pea and the 

 clover are abundant enough. 



Similar experiments have been repeated elsewhere until it has 

 become evident that the root tubercle bacteria are not all alike. 

 Varieties adapted to one species of legume may be unable to produce 

 tubercles upon a second species; in some cases one type of bacteria 

 may be able to grow in the roots of several allied legumes but not 

 in others. For example, the tubercle organism of sweet clover 

 will do well with alfalfa. All of these facts have suggested that 

 there are different types of leguminous bacteria, each adapted to 

 different species of legumes. 



To what extent this conclusion is true it is by no means easy to 

 determine. It is certainly true that some varieties of legume^will 

 grow in soils with an abundant production of tubercles, while 



