THE NEW EARTH 



the agricultural college was a complete failure 

 and no tubercles appeared upon the roots. 

 The failure was pronounced a case of nitrogen- 

 hunger. Inoculation was then tried, and the 

 results were wholly satisfactory. On soil from 

 a cotton field which had been cleared twenty 

 years the gain was seventy-one per cent; soil 

 five years cleared, seventy -four per cent; 

 woodland, three hundred and twenty-six per 

 cent. The average of all the soils showed an 

 increase due to inoculation of one hundred 

 and fifty-eight per cent in tops and one hun- 

 dred and twenty-eight per cent in roots. 



Extensive tests have for several years been 

 under way in Illinois at the state experiment 

 station as to the importance of bacteria in 

 producing the plant-food. Experiments were 

 made with various legumes, among them cow- 

 peas, soy beans, red clover, alfalfa and sweet 

 clover. Emphasis was laid in these tests upon 

 the fact that these plants, and others of their 

 class which are known to restore fertility to 

 soils, do not take their nitrogen from the air 

 but are given it by the bacteria, which take it 

 from the air and convert it into food for the 

 plants. With the inexhaustible supply of ni- 



44 



