Rhizobium is free living nitrogen fixing bacteria. Itcolonizes the roots of legumes to form tumour like growths called root nodules. These root nodules fixesatmospheric nitrogen as ammonia. This is utilized by the plant to produce proteins and other nitrogen containing compounds.
By artificially inoculating roots with rhizobium, they can be made to fix atmospheric nitrogen. It has been estimated that 40-250 kg nitrogen / ha / year can be fixed by rhizobium.
Rhizobium is used for seed treatment of legumes (Cow pea, chick pea, soybean, beans etc.).Commercially it is available as carrier based inoculum. For treating 5-10 kg seeds, 500g culture is required.
Take 500gram culture in a plastic tray/basin.Moisten the seeds by sprinkling water or rice-gruel water (500 ml). Add moistened seeds, mix well and dry in shade for 30 minutes. The treated seed should be sown immediately.