4 METHODS OF LEGUME INOCULATION. 



from some other species. In other words, the red clover bacteria, 

 which will produce a very successful inoculation when applied to a 

 crop of red clover, will give little, if any, beneficial action when applied 

 to cowpeas or soy beans, and vice versa. 



THE SOIL-TRANSFER METHOD OF INOCULATION. 



The soil-transfer method consists in scattering over the new ground, 

 at the rate of 200 or 300 pounds to the acre, soil either from a healthy 

 old field of the same crop or from a new field of the same crop that 

 shows abundance of nodules on the roots. To facilitate even scat- 

 tering the inoculated soil should be thoroughly mixed with several 

 times its weight of ordinary soil, and may be either drilled or broad- 

 casted. If the soil is broadcasted it should be harrowed in immedi- 

 ately, and if possible this should be done toward evening or on a 

 cloudy day, as bright sunshine is very harmful to the bacteria. 



THE PURE-CULTURE METHOD OF INOCULATION. 



The method of inoculation by pure cultures depends to a. certain 

 extent upon the type of pure culture which may be used. Generally 

 speaking, however, a bottle of pure culture of the proper kind of bac- 

 teria is opened shortly before the seed is to be planted and the culture 

 mixed with the proper quantity of water and applied to the seed in 

 such a way that all of the seed may be moistened, though not soaked. 

 The seed should be planted as soon as practicable after this treat- 

 ment; that is, as soon as it is sufficiently dry for convenient hand- 

 ling. Drying may be facilitated by adding dry, sifted earth, prefer- 

 ably from the field in which the leguminous crop is to be grown. It 

 is undesirable to store inoculated seed, as the nodule bacteria often 

 die out rapidly after the seed has been treated with the pure cultures 

 and dried. Inoculated seed should never be dried in the sun. It is 

 also possible to thoroughly mix the pure culture with a considerable 

 quantity of soil, preferably from the field where the legume is to be 

 sown. The treated soil can then be distributed in the same manner 

 as when inoculating by the use of soil from an old field. 



The advantages of the artificial cultures lie in the greater ease of 

 their transportation and application as well as in the absence of the 

 danger of introducing harmful w^eeds or plant diseases, although this 

 method of inoculation, especially in the case of alfalfa, is less certain 

 than the soil-transfer method previously described. 



Attempts to secure inoculation either by the use of pure cultures 

 or by the use of soil from old, well-inoculated fields will fail if the crop 

 which is being experimented with is not adapted to the locality or if 

 the climatic conditions during the growing season are unfavorable. 



[Cir. 63] 



