28 FARMERS' BULLETIN 797. 



inoculation is very essential to success. Ordinarily it is not neces- 

 sary to inoculate sweet clover when it is to be planted on land where 

 alfalfa, bur clover, or black medic thrives, because the same strain 

 of inoculating germs inoculates all of these plants. However, when 

 this clover is to be planted on land where none of the plants inocu- 

 lated by this strain of the organism have been grown, inoculation 

 should be provided. In localities where sweet clover or other plants 

 inoculated by the same, strain of bacteria thrive, the early growth 

 has at times been made much more vigorous by inoculating the soil 

 or seed thoroughly. 



It is not safe to assume that a certain piece of soil is inoculated 

 because any one of the plants inoculated by the same strain of the 

 organism is growing or has been grown on other fields in the same 

 vicinity. Many fields haA~e come under observation where sweet 

 clover was a failure because the plants were not inoculated, when 

 plats or fields of alfalfa growing near by were abundantly inocu- 

 lated. 



There are several methods of inoculating sweet clover, any one of 

 which when properly applied should give good results. 



THE SOIL-TRANSFER METHOD. 



m 



The soil-transfer method of inoculation consists in scattering over 

 the field to be seeded 200 to 400 pounds to the acre of soil collected 

 from sweet-clover, alfalfa, or bur-clover fields where the healthy 

 plants show an abundance of tubercles on the roots. It is strongly 

 recommended that this soil be scattered on a cloudy day or in the 

 early morning or in the evening and immediately harrowed or disked 

 into the ground, as the sun's rays are very injurious to the inoculat- 

 ing germs. It is a good plan for the person scattering the soil to 

 walk directly in front of the harrow. When this practice is followed 

 little harm can be done by the light. To facilitate even scattering, 

 the soil may be mixed thoroughly with two or three times its weight 

 of other soil, preferably from the field where the sweet clover is to 

 be sown. Soil used for inoculating sweet clover does not necessarily 

 have to be scattered on the land just previous to sowing the seed. It 

 may be scattered a few months or a year in advance of the time the 

 sweet clover is to be seeded and be just as effective as if it were 

 scattered at a later time. In general, where sweet clover is to be 

 seeded in the spring on winter grain, the inoculation should be ap- 

 plied before the grain is sown. 



Good success has been obtained by drying in a dark place soil con- 

 taining the inoculating germs, sifting it, and running it through the 

 fertilizer compartment of a grain drill. When this method is em- 

 ployed it is not necessary to use as much soil as when it is scattered 

 broadcast. 



