CONDITIONS AFFECTING LEGUME INOCULATION. i i 



The accompan3'ing illustration (PL VIII) shows characteristic pots of 

 red clover from a series of soils from South Salem, N. Y., where clover 

 had been steadil}^ diminishing in vigor for 3^ears. The nodules on the 

 unlimed plants were small and clustered around the crown of the 

 plant, while the limed plants showed numerous nodules well dis- 

 tributed. The stand secured in a series of limed pots was four 

 times as heavy as without the use of lime. 



In comparison with this unfavorable soil, the extract obtained from 

 soil sent in from a favorable field test at Carlisle, Pa., gave an excel- 

 lent growth of the red clover bacteria, and the inoculated red clover 

 grown in this soil in pots showed numerous nodules and a better 

 growth than in the uninoculated pots, thus confirming results obtained 

 in the field. 



It may be noted that there is a difference exhibited among different 

 legumes in their behavior toward lime. While for most legumes its 

 effect is beneficial, a few species, such as lupine and serradella, are 

 actually injured by its use" and some other legumes, such as Lima bean 

 and cowpea, do not respond to lime even in soils where clover refuses 

 to grow without lime. It has been noted* that serradella is not suc- 

 cessful when following red clover, and that results are also unsatisfac- 

 tory when red clover follows serradella. These varying relations 

 shown by legumes belonging to different groups in their relation to 

 lime and other conditions emphasize the necessity of determining as 

 accuratel}" as possible the adaptabilit}" of different soils to the crops 

 for which they are intended. 



Observations upon the occurrence of nodules in certain soils have 

 been found to correspond quite closely with the behavior of the soil 

 solution toward the bacteria of the legumes tested. The preceding 

 table illustrates this point, though perhaps not so clearly as the follow- 

 ing examples. 



In the case of a fairly rich garden soil, soy beans would not form 

 nodules even after very heavy inoculation, and the extract from this 

 soil used as a culture medium was found to inhibit the growth of the 

 soy bean bacteria. On the other hand, alfalfa readily formed nodules 

 in this soil and the soil extract was not unfavorable to the growth of 

 the alfalfa bacteria. 



A soil from Niles, Mich., which had grown a fair crop of soy beans 

 for four 3^ears without the occurrence of nodules, was tested. The 

 soil extract in this case was found unfavorable to the growth of the 

 soy bacteria. In greenhouse pot tests ^oj beans of several varieties 

 failed to produce any nodules in this soil even when heavily inoculated 

 with cultures which produced abundant nodules in other soils tested 



aSee Ehode Island Agr. Exp. Sta. Kept., 1896, p. 256; also Bui. 96 of same 

 station, 1903. 



6 Deutsche Landw. Presse, vol. 32, 1905, p. 799. 

 100— Tin 



