INOCULATION 353 



eight hundred pounds of inoculated soil should be applied to 

 each acre of the new field if the inoculated soil can be obtained 

 near by. If it must be shipped from a distance, from 200 

 to 300 pounds may be made to suffice, thus reducing the 

 expense of transportation. This inoculated soil may be 

 mixed with several hundred pounds of ordinary soil before 

 it is applied, since the larger quantity can be spread more 

 easily and evenly. Rather than attempt to establish a large 

 area at first, it is often better to start a small plat and then 

 use soil from it to inoculate the larger fields. 



Where the distance from an old field makes inoculation 

 by soil transfer too expensive, what is known as the "pure 

 culture" method of inoculation may be used, though it is 

 less generally successful than the other methods. The 

 bacteria are grown artificially in culture media, and shipped 

 either in the dry form similar to cakes of yeast, or in tubes 

 containing the liquid solution. Before using the powder 

 or liquid it is put into a vessel containing water, a little 

 sugar, and other suitable material for the growth of the 

 bacteria. In a few days the water takes on a milky hue from 

 the large increase in numbers of the bacteria, and it is then 

 sprinkled on the seed or is mixed with soil and spread on the 

 field. It is much easier to inoculate the seed, which should 

 then be sown within a few days. Inasmuch as the desired 

 bacteria are present in small numbers in most soils and are 

 usually present on the seed, complete inoculation is often 

 secured by gradually increasing their number. This is 

 best done by mixing a small quantity of the seed of the 

 legume desired along with the grass seed. In a few years 

 the bacteria will have increased sufficiently to insure 

 the success of a straight legume seeding. This explains 



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