Inoculant is Rhizobium bacteria that is applied to legume seed (clovers, cowpeas, etc.) before planting. The nodules on the roots of legumes contain Rhizobium bacteria, which are responsible for fixing nitrogen for the plant. Applying inoculant to the seed ensures that the correct type of bacteria specific to that legume are available to the plant once it germinates. http://www.glory-metallurgy.com/inoculant/