114 



Results of inoculation experiments on vrinison clover, 



using ''Nitrag^in.'^ 



Thus, it may be seen that when attempted inoculation 

 with pure cultures is effective, the increase in crop is 

 highly satisfactoiy. In the experiments tabulated above, 

 inoculation in several instances increased the yield more 

 than three-fold. 



The above figures give the favorable side of inoculation 

 with '^Nitragin.-' Its use was, however, found impracticable 

 because so often the germs in it were dead and inoculation 

 did not result. 



EXPERIENCE IN RECENT YEARS WITH PURE CULTURES OR 

 ARTIFICAL INOCULATING MATERIAL. 



In recent years the United States Department of Agri- 

 culture and a number of commercial firms have engaged 

 in the manufacture of pure cultures, a special kind for the 

 inoculation of each particular legume. At first these were 

 sent out in the form of wisps of dried cotton, on Avhich the 

 proper germrs were lodged. This Station had numerous 

 tests of these cultures made on a great variety of soils. The 

 result was a long list of failures, with few. if any, suc- 

 cesses. 



A later improvement was the sending of the cultures in 

 liquid form in sealed tubes. The experience of this Station 

 with these was. on the whole, unsatisfactory. For example. 



