LEGUMINOUS FORAGE CROPS I2Q 



diminution in yield, even though non-nitrogenous fertilizers 

 alone were used. Hall x found an annual gain of 25 pounds of 

 nitrogen per acre on Geescroft field, for the period 1882 to 1904, 

 and that notwithstanding the fact that this field bore no 

 leguminous vegetation. 



137. Dissemination of the Bacteria by Natural Means. The 

 bacteria found in the tubercles of each germs, and, perhaps, 

 of each species of leguminous plants, differ in some ways from 

 those found on others. The various bacteria are generally 

 regarded to be so closely allied that forms on one species of 

 legume may adapt themselves to other closely allied species 

 and genera. It is held to be probable that the time required 

 for one form to adapt itself to an unaccustomed host depends 

 somewhat on the degree of relationship between the respective 

 host plants. It has been found in practise that closely related 

 species of legume when following each other bear tubercles 

 freely without any inoculation of the soil; that distantly related 

 species the first year of planting on new ground do not gen- 

 erally bear tubercles freely the first year, but do so generally 

 the second or third year when the sowing is repeated on the 

 same ground. 



The New York State Station has determined that these or- 

 ganisms usually die within a few days when dried under the 

 usual atmospheric conditions. 2 The inoculation of one plat of 

 ground from an adjacent plat has not been found to occur 

 commonly, except through the washing of soil from one plat 

 to another. Much more extended and accurate observations 

 are necessary in order to determine the means and conditions 

 under which the organisms are disseminated. 



"Not every leguminous plant requires artificial inoculation in order to 

 produce tubercles. Many soils are naturally supplied with the tubercle-pro- 

 ducing germs through the growth of wild leguminous plants. Moreover, where 



1 Journal Agr. Science I, May, 1905. 



2 New York State Sta. Bui. No. 270 (1905), c. 382. 



