SOIL ORGANISMS 439 



have disappeared because of unfavorable conditions. If leg- 

 umes, especially of certain types, are to be grown most suc- 

 cessfully, the specific strains of B. radicicola for that crop 

 must be present. 



Two general methods of inoculation are available: (1) the 

 use of soil from fields where the particular legume in ques- 

 tion is growing or has grown successfully.; and (2) the utiliz- 

 ation of artificial cultures of some form. Bacillus radicicola 

 is found in the soil as well as in the plant nodules. As a 

 matter of fact, this bacterium will live in the soil for long 

 periods, even if the host plant is not grown. Whether it fixes 

 nitrogen to any extent under such conditions is a question. 

 At least the organism does not lose its virulence. Such soil 

 may be spread on the land to be inoculated at the rate of 

 300 to 500 pounds to the acre. It should be applied in the 

 evening or on a cloudy day and harrowed in as soon as pos- 

 sible, as the organisms are injured by direct sunlight. 



The soil carrying the organism may also be mixed after 

 air-drying with the seed, the latter having been moistened with 

 a dilute glue solution. 1 Enough of the dry earth sticks to 

 the seed to carry the organisms into the soil. The advantage 

 of this method is that the bacteria are in contact with the seed 

 and the plants become infected very soon after the seeds 

 germinate. The main objection to the soil method of inocu- 

 lation lies in the possibility of spreading plant diseases and 

 undesirable weeds. 



1 Dissolve ordinary furniture glue in boiling water, two handfuls of 

 glue to every gallon of water used, and allow the solution to cool. Put 

 the seed in a wash-tub, and then sprinkle enough of the solution on the 

 seed to moisten but not to wet it (one quart to a bushel is sufficient), 

 and stir the mixture thoroughly until all the seeds are moistened. 



Dry the inoculating soil in the shade, preferably in the barn or base- 

 ment, and pulverize it thoroughly into a dust. Scatter this dust over the 

 moistened seed, using from one-half to one gallon of dirt for each 

 bushel of seed, mixing thoroughly until the seed no longer stick together. 

 The seed is then ready to sow. 



See Vrooman, C, Grain Farming in the Corn Belt with Live Stock as 

 Side Line; Farmers' Bui., No. 704, 1916. 



