SOIL INOCULATION 



addition of the foreign soil. The experiments 

 were carried on in small plots and in larger 

 farm areas as well. 



In all cases the results were the same; the 

 beans which were planted in the pinch of 

 Massachusetts soil produced roots abounding 

 in tubercles, while those planted under pre- 

 cisely similar conditions, but without the eas- 

 tern soil, produced no tubercles. It was found 

 in greenhouse tests that the bacteria began 

 their work of storing up nitrogen very soon 

 after the sprouting of the seed, increasing their 

 activity as the roots began to develop. When 

 the beans were fairly well advanced, some of 

 the hills were dug up, about two cubic feet of 

 soil being taken up with each hill. After a 

 thorough washing, tubercles were found in 

 large numbers upon the plants which had been 

 inoculated, but not one upon the plants which 

 had not been inoculated. 



In order to find out whether or not the soil 

 once inoculated would become of itself a 

 medium for further inoculation, experiments 

 were undertaken with the Kansas soil in which 

 the beans had been grown, and proof was soon 

 at hand that the home soil, once inoculated, 



37 



