THE ACOUISITIOX OF ATMOSPHERIC NITROGEN'. 

 SOIL INOCULATION. 



W. M. Muxsox. 



The remarkable results obtained at the Alabama Experiment 

 Station* from the inoculation of sterile soils with tubercles from- 

 various leguminous species, and with nitragin, were referred to 

 by the writer in the last report of this Station.j With the pur- 

 pose of verifying this work and of comparing several of the- 

 ■'nitragin" cultures with each other and with tubercles from. 

 various species of legumes, a series of inoculation experiments 

 was undertaken in the greenhouse during the past season. 



For all the work a sterile, sandy subsoil was used. This soil 

 was sterilized once by being placed in a tight box in which was 

 a coil of perforated steam pipe. Steam, at lo pounds pressure^ 

 was passed through the coil for one hour, thus maintaining a. 

 temperature of about 200 degrees F. Just before use the soil 

 was again sterilized, for one to one and one-half hours, on three- 

 successive days. On these occasions the steam w^as at 8o- 

 pounds pressure. The pots used were all sterilized by steaming 

 for one hour on three successive days and the house was thor- 

 oughly sprayed with corrosive sublimate before the pots were 

 put in place. Throughout the test, the water given to the plants, 

 was boiled for one to one and one-half hours, on three succes- 

 sive days, before use. Each six-inch pot was given 6.2 grams 

 of complete fertilizer which was first carefully sterilized. 



The seed was in all cases soaked for one and one-half hours- 

 in corrosive sublimate (i gram to i quart water), placed in a. 

 sterilized germinatori and moistened with sterilized water. 



*Bnll. 87 Alabama Experiment Station, 466. 



jRep. Maine Experiment Station, 1897, 130. 



i The germinator consisted of folds of asbestos cloth ■which ■were passed 

 through a flame and then placed in a "Geneva tester" ■which had been similarly- 

 treated. 



