188 AGRICULTURAL EXPERIMENT STATION. [Jan. 



An examination of the above tabular statement of the 

 annual yield of the various crops upon the different plate 

 shows that as a rule those plats (4, 7, 9) which had not 

 received in any form nitrogen for manurial purposes yielded 

 much smaller crops than those that received annually in some 

 form or other an addition of available nitrogen. It seemed 

 but proper to sum u}) in our last annual report our results in 

 the following statement : — 



The experiments carried on upon Field A during the years 

 1889, '90, '91 and '92 show condusiveli/ the importance of 

 a liberal supply to the soil of an available form of nitrogen, to 

 serve a successful and remunerative cultivation of farm crops 

 under otherwise corresjionding favorable conditions. For even 

 a leguminous cropy the soja bean, ichen for the first time 

 raised upon Field A, did not furnish an exception to our 

 observation. 



The stated conclusion is in full accord with careful obser- 

 vations of others when raising upon a field for the first time 

 clover or clover-like plants. A deficiency of the soil in 

 regard to the peculiar lower organisms, which in case of 

 clover-like plants are recognized as the medium to assist in 

 the conversion of the atmospheric nitrogen into nitrogenous 

 plant food, is usually considered the cause of the results. 

 This class of crops frequently does better on a second trial 

 upon the same lands. 



A liberal introduction of annual leguminous crops into 

 our system of raising field crops is known to improve the 

 nitrogen resources of the farm lands in an economical way. 



1893. — The main object of our experiment upon Field A 

 during this season was to observe the after-effect of the cul- 

 tivation of soja bean (a leguminous crop) on the nitrogen 

 resources of the soil which served for its production. It 

 seemed of interest in our case to ascertain whether the rais- 

 ing of the soja bean upon Field A had increased the amount 

 of available nitrogen stored up in the soil to such an extent 

 as to affect the yield of the succeeding crop upon those plats 

 (4, 7, 9), which as a rule did not receive at any time an ad- 

 dition of available nitrogen from any other manurial source 

 but the atmospheric air and the roots of the soja beans left 

 in the soil after harvesting the crop. 



