1 88 FIXATION OR ASSIMILATION OF NITROGEN 



From this table it is seen that the annual amount of 

 nitrogen in a crop of beans or clover is more than double 

 that in a cereal crop grown under similar conditions side 

 by side on the same field. In Little Hoos Field, Rotham- 

 sted, barley was grown in 1873 adjoining a plot of 

 clover : both received the same treatment, and the soil 

 was uniform in character. The amounts of nitrogen 

 obtained in the two crops were : 



Lbs. of Nitrogen 

 per Acre. 



In the barley. . . . 37.3 

 In the clover . . . . 151.3 



In the following season barley was sown on both plots, 

 the nitrogen obtained in the crop being : 



Lbs. of Nitrogen 

 per Acre. 



In the barley after barley . 39.1 



In the barley after clover . 69.4 



Difference . 30.3 



From the figures given above it is seen that the clover 

 contained more than four times as much nitrogen as the 

 barley growing side by side with it in the same field : 

 moreover, the soil of the plot from which the clover was 

 cut was left so much richer in nitrogen than that on 

 which barley had been grown that another barley crop 

 in the following year was able to obtain over 30 Ibs. 

 more of nitrogen from it than from the latter plot. 

 Chemical analysis also showed an increased nitrogen- 

 content in the soil which had grown a clover crop over 

 that from which barley had been harvested. 



^Herr Schultz obtained results of a similar nature on a 



