182 SOIL ORGANISMS IN RELATION TO SOIL FERTILITY 



since they could grow excellent clover and corn, alfalfa should 

 likewise do well. 



It is necessary that legumes have these bacteria to help them 

 secure the large amount of nitrogen they demand. In exceptionally 

 rich soils the nodule bacteria are not so necessary, because there 

 the plants are able to secure their nitrogen requirement directly 

 from the soil. It is usually true that wherever a certain legume 

 has never been grown, there a lack of the proper bacteria prevails — 

 except in cases where the same bacteria can grow on one legume as 

 well as on another. 



Alfalfa bacteria grow without difficulty on sweet clover, bur 

 clover and black medick; or vice versa. 



The bacteria causing the formation of nodules on medium 

 red, alsike, crimson, mammoth and white clovers may be grown 

 interchangeably. 



The nodule bacteria on the following legumes can grow on one 

 as weU as on another: Garden, field, and sweet peas, and vetch. 



Soil Inoculation. — It is a comparatively simple matter to add 

 to a soil the necessary legume bacteria. This process is called 

 ''soil inoculation.'' Usually, whenever a particular legume is to 

 be grown on a field for the first time, and especially when for the 

 first time in that locality, it is a safe rule to inoculate the soil. 

 If the legume is soybean, inoculate with soybean bacteria; if 

 alfalfa, inoculate with alfalfa bacteria; if it is field pea, inoculate 

 with field pea bacteria, etc. The successful growing of the com^ 

 mon garden pea may depend largely on proper inoculation. 

 (Fig. 122.) 



Methods of SoE Inoculation. — Several common methods are 

 used in inoculating soils. Soil may be taken from one field growing 

 the legume successfully and applied to another field upon which 

 is to be grown the same legume. The soil is taken from the surface 

 six or eight inches. A bushel of well pulverized soil is sufficient to 

 inoculate one acre, though farmers usually use about a wagon-box 

 full for three to four acres. Usually the soil is spread by hand. 

 Since sunlight is a destroyer of germ life, it is necessary, if the soil 

 is quite dry and the sun is shining bright and warm, to harrow the 

 land immediately after the inoculating soil is apphed. 



The seed-agglutination method of inoculating for legumes is 

 now commonly used. Procure a peck of soil which has plenty of 

 the right kind of bacteria. Put half of this into a tub of clean 

 water. Stir thoroughly and while stirring add a pint of liquid glue 



