Rhizobium requires specific host plants for nitrogen fixation to occur. Sometimes bacteria infect the root but are not able to fix nitrogen. In other situations, bacteria fix nitrogen but cannot enter the root, so nodulation does not occur. The Need for Inoculation Inoculation refers to the addition of effective rhizobia to legume seed prior to planting. All legumes should be inoculated with rhizobia, even if the legume has previously been grown in the soil.
Inoculation provides the most effective strains of bacteria for the type of legume.
There are three common methods to inoculate seed. The seed should be sown immediately after inoculation. Slurry Mix inoculum with water in amounts indicated on the package to form a slurry, then pour slurry on seed and mix well. If done properly, the seed will absorb the water leaving an even, dry coat of inoculum. This method is a modification of the slurry method using an adhesive solution instead of water.