

NON-SYMBIOTIC NITROGEN FIXATION 429 



only a question of time until a successful method of 

 inoculating soil from artificial cultures will be found. 

 In the meantime, inoculation by means of infested 

 soil is the most practical method. 



291. Nitrogen-fixation without symbiosis with 

 higher plants. If a soil be allowed to stand idle, either 

 without vegetation or in grass, it will, under favorable 

 moisture conditions, in the northern states, accumu- 

 late in one or two years an appreciable amount of 

 nitrogen not present at the beginning of the period. 

 At the Rothamsted Experiment Station, one of the 

 fields in volunteer plants, consisting mainly of grass 

 without legumes, gained in the course of twenty years 

 about twenty-five pounds of nitrogen per acre, annually. 

 According to Hall, the nitrogen brought down by rain 

 would account for about five pounds per acre per 

 annum, and dust, bird-droppings, etc., for a little 

 more. As pointed out by Lipman, there must also 

 have been a greater total accretion of nitrogen during 

 the twenty years than appears in the final result, as 

 considerable must have been lost through removal 

 of nitrates in drainage and escape of nitrogen in the 

 ordinary processes of its transformation. 



292. Nitrogen-fixing organisms. Direct experi- 

 ment has shown that certain bacteria have the ability 

 to utilize atmospheric nitrogen and to leave it in the 

 soil in a combined form. A bacillus Clostridium 

 pasteurianum was first found to produce this result. 

 Later, a commercial culture called " Alinit" was placed 

 on the market in Germany, which culture it was claimed 

 contained Bacterium ellenbachensis , with which the 



