184 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY 



stir until the moisture is taken up by the soil. The seeds are now 

 ready to be drilled in the field. 



Another common way to inoculate is to apply the bacteria to 

 the seed as pure culture at the time of seeding or planting. Pure 

 inoculation cultures are bacteria grown in the absence of all other 

 kinds of bacteria on sterilized foods. These pure cultures may be 

 sent out to farmers in liquid form, on vegetable jelly, or in steril- 

 ized soil. Good results are secured through this method of inocu- 

 lation only when fresh cultures containing the proper organisms 

 are used. Farmers may secure pure inoculation cultures from the 

 United States Department of Agriculture, from their State Experi- 

 ment Station, or from reliable seed houses. Full directions for 

 using accompany the cultures. 



Some recommend the sowing of about a pint of alfalfa seed per 

 acre in with the usual seeding mixture of- clover and grass as a 

 means of inoculating the soil for alfalfa. In actual practice this is 

 not a safe and sure method of inoculation. It is rather a test to 

 determine whether or not the soil conditions are right for alfalfa. 

 Moreover, an acid soil is usually lacking in the alfalfa nodule- 

 bacteria, so that any attempt to grow a few alfalfa plants on such 

 a soil results in failure, not only because of the lack of the proper 

 organisms, but also because of the lack of lime. To be sure of 

 inoculation on non-acid soils it is best to inoculate with soil or 

 pure culture. On acid soils, the only sure way to succeed, especially 

 with alfalfa, is to lime the land first, then inoculate. 



How Often to Inoculate. Usually when a soil becomes inocu- 

 lated and grows a certain legume successfully, further inoculation 

 for that particular legume is unnecessary, provided the soil con- 

 ditions remain favorable for the bacteria. 



Conditions Favoring Soil Organisms. As in case of all living 

 things, the growth and activity of all the helpful soil organisms 

 are promoted only when favorable conditions surround them. 

 Aside from food and suitable moisture and temperature conditions, 

 they particularly require a well-aerated soil, a soil containing a 

 sufficient amount of organic matter, and most of them require a 

 soil not sour or acid. These last three conditions are within the 

 control of the farmer, thus making it possible for him to plan and 

 direct his farming operations in such a way as to foster these tiny 

 workers in the soil. 



