EIGHTEENTH ANNUAL YEAR BOOK— PART VIII 



443 



YIELD PER ACRE IN POUNDS OF ALFALFA, COWPEAS AND SOYBEANS 

 WITH DIFFERENT INOCULATION MATERIALS. 



TOTAL N IN CROP PER ACRE POUNDS. 



Alfalfa 1914 

 Alfalfa 1915 

 O'owpeas .— 

 Soybeans — 



160.06 

 201.28 

 88.26 

 108.22 



187.04 

 221.72 

 133.42 

 156.40 



170.76 



215.90 



116.24 



*106.6O 



176.14 



218.20 

 34.12 

 141.32 



171.88 

 204.62 

 117.00 

 151.84 



217.72 

 121.62 

 »114.52 



186.08 



170.76 



The cross inoculation of alfalfa with sweet clover proved quite as 

 satisfactory as when alfalfa cultures were used. A pure culture used 

 in addition to soil for inoculation showed some slight effect but not 

 sufficient to warrant the use of a pure culture on a soil already well 

 inoculated. 



Inoculation of the legumes increased their nitrogen or protein con- 

 tent as well as their yields. Again, however, the effects of the differ- 

 ent cultures are not suffilciently distinctive to warrant a conclusion 

 regarding the relative merits of the various pure cultures and of soil 

 for inoculation. There is apparently a tendency toward equalization 

 between the total crop yield and the nitrogen content. When the crop 

 is larger, the nitrogen content is somewhat lower and vice versa. 



These experiments are of value in that they show rather definitely 

 that the particular pure cultures tested gave satisfactory inoculation 

 for the legumes used and partically as good results were secured with 

 them as by the use of well-inoculated soil. 



HOW TO IXOCtTLATE 



The choice between the two methods of inoculation must, therefore, 

 rest upon the expense and labor involved in their use. If soil is avail- 

 able in the immediate vicinity and can be secured for the labor and 

 expense of hauling and spreading it over the field to be seeded, it is 

 the cheaper and safer method of inoculation. Such soil must of course 

 be secured from a field where the same legume has been grown and 

 well inoculated and where no objectionable weeds or plant diseases have 

 been present. In addition, soil used for inoculation should be disked 

 in at once in order to avoid weakening and killing of the bacteria. 



♦Seeded June 8. All other plots seeded May 27. Delay in securing cultures. 

 Crop harvested on same date. 



