Definitions for "Inoculant"
Keywords:  legume, rhizobia, peat, seed, bacteria
A commercial preparation, often but not always based on peat, that is used to introduce rhizobia into soils. Inoculants may be seed applied or introduced directly to the soil.
Legumes fix nitrogen, making it available for itself and other plants. On its roots are pinkish nodules wherein the legume participates in a mutually beneficial relationship with soilborne bacteria. The bacteria make nitrogen fixation possible. The soil where a legume is planted does not necessarily harbor the bacteria necessary for fixation and so must be inoculated with it. The inoculant contains the bacteria. It can be purchased in powdered or granular form and applied directly to the soil (and sometimes to the legume seed itself). Each legume has its own, specialized bacteria. If you suspect that the soil lacks the necessary bacteria, pull up a legume plant and look for the nodules; if you have trouble seeing any, the soil may need inoculation.
in this instance, nitrogen fixing bacteria.
The dried or inactive microorganisms that become active when added to the compost pile. Inoculants are not required for composting.