382 FIELD CROPS 



attain success. This inoculation may be by means of soil 

 from an old alfalfa field, or by the use of pure cultures of the 

 bacteria. The use of soil from old fields is more generally 

 successful. As the bacterium on sweet clover is apparently 

 the same as that on alfalfa, the inoculation of fields where 

 this plant grows freely is not often necessary, for the bacteria 

 transfer readily from one to the other. The bacterium from 

 red clover will not grow on alfalfa. When a good stand of 

 alfalfa is once obtained, it is then easy to spread the bacteria 

 to other fields by scattering a few hundred pounds of the soil 

 from the old field over each acre of the new. The same 

 result may be obtained if manure from stock which have been 

 fed on alfalfa hay is used, while the dust blown from one 

 field to another often carries enough bacteria to inoculate 

 land on which the crop has not previously been grown. 



481. Treatment of New Meadows. If alfalfa is sown in 

 the spring, it is likely to need some attention during the first 

 season in keeping down weeds. If the weeds are numerous 

 and threaten to destroy the stand of alfalfa, the plants should 

 be clipped back with the mower to a height of about 6 inches. 

 If the plants begin to turn yellow, clipping will often start 

 them into vigorous new growth. If this yellowing is due to 

 disease, the clippings should be burned, otherwise they 

 may be left as a mulch. If the alfalfa is not sown 

 till late summer or early fall, no clipping or other treat- 

 ment is usually necessary that year, and the following season 

 one or more crops of hay may be cut. The field should not 

 be pastured the first or second year, for the young crowns are 

 quite easily destroyed. Later, when they become more 

 firmly established, some pasturing is possible. 



482. Treatment of Old Meadows. On loose soil no 

 treatment is ordinarily given to alfalfa meadows other than 

 an occasional harrowing. On land which is inclined to pack, 



