METHODS OF INOCULATION 



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lation of soils for the growth of legumes are in use. When once 

 inoculated thoroughly the soil will not need it again for the same 

 group, unless long periods elapse between years when those legumes 

 are grown on that soil. 



The soil-spreading method is to get a little top soil from a place 

 where the same plants have been very successfully grown, spread 

 it on the new place and harrow it in 

 before the hot sun has any chance to 

 kill the bacteria. The rate of spread- 

 ing the soil may be about 200 to 500 

 pounds per acre. The amount re- 

 quired will depend chiefly upon the 

 method of spreading. More soil will 

 be required if it is to be spread with 

 a shovel. A rapid plan is to spread 

 the soil with a lime spreader or fertilizer 

 drill. It may also be sown broadcast 

 by hand, as seed is sown. 



The aglutination method is to take 

 a few shovels full of good, rich soil 

 from a spot having plenty of the bac- 

 teria, and put it in a barrel or tub of 

 water, add a halfpint of liquid glue and 

 a quart of lime water to ten gallons of the liquid. Stir thoroughly 

 and wet the seeds with this liquid. Put the seeds in a box and pour 

 the liquid over them and mix with a shovel or hoe until all are 

 wet. Then spread the seeds on a smooth floor or canvas to dry 

 in the shade. Sow them as soon as they are dry enough, and har- 

 row them in very promptly. 



The building-up method is founded on the fact that nearly all 

 soils have at least a few bacteria for all of the groups of legumes. 

 If some seeds of the legumes are sown with other crops for a few 

 years they will naturally increase the number of legumes and 

 rather complete inoculation may be the result. 



Artificial cultures of bacteria for most of the legumes are fur- 

 nished free by the U. S. Department of Agriculture and some 

 state experiment stations. They are sold at about two dollars per 

 acre by seed companies and others. In general the liquid or 

 gelatin cultures are to be mixed with sterilized water and then the 

 seed is to be wet with it and dried before planting. Special direc- 

 tions accompany each of the packages of artificial culture. 



Fig. 200. — Soybeans, when well 

 supplied with bacteria and nod- 

 ules, will gather much nitrogen 

 from the air and improve soils. 



