What is Rhizobia Inoculant

Inoculants are commercially prepared Rhizobia bacteria responsible for fixing nitrogen that are applied to legume seeds. Applying inoculants to the seed ensures that the correct type of bacteria specific to that legume are available to the plant once it germinates. Legumes have the ability to form a symbiotic relationship with rhizobia bacteria to convert atmospheric nitrogen gas to ammonium nitrogen, a form usable by the plant. This process occurs in the nodules of legumes which occur in the plant's root system. The bacteria invade plant root hairs and multiply in the outer root tissue. The plant supplies energy to the bacteria from photosynthesis and the bacteria convert nitrogen gas to ammonia in the nodules. Some legumes produce enough ammonium nitrogen to supply all their nitrogen needs thus eliminating the need for expensive chemical nitrogen fertilisers.


Plants require nitrogen to form chlorophyll so as to manufacture proteins and other complex organic compounds within the plant. Few soils contain effective root nodule bacteria strains necessary to promote maximum growth of legumes. The aim of inoculation is to get as many viable nitrogen fixing bacterial cells from the inoculum on and around seed root when germination occurs. Proper inoculation may mean the difference between success and failure of a legume crop especially when growing the legumes for the first time.

Rhizobia that grow on the plant roots convert free atmospheric nitrogen into nitrates which the plant uses to grow. Manufactured mineral nitrogen fertilizers give plants with deep green colour, but have been proven not to offer the yield advantage that rhizobia inoculation does.Inoculation replaces the need for applying expensive fertilisers

 How to Apply Rhizobia Inoculants to Legume Crop

General                                Work in a cool shaded place

Have                      1) one clean bucket

                                2) one larger plastic sheet

                                3) one litre jug with measuring lines

                                4) one wooden spoon

                                5) two to three table spoons of sugar

                                6) one sharp knife or pair of scissors

Method                               1) dissolve the sugar in 500ml of water in the bucket

                                2) cut open pack and tip all the contents into it and stir very well for one minute

Inoculation         1) tip the quantity of seed onto to the plastic sheet

                                2) apply the inoculum whilst still stirring

                                3) mix the seed very gently until all are covered and look shiny wet

                                4) if you have any inoculum over apply it to the soil where the seeds are to be planted                                   


Sow into moist soil as soon as possible after inoculation and cover the seed immediately.

The inoculated seeds     a) must not be sown into dry soil and left for several days before irrigation

                                                b) must not be exposed to the sun for a long time

                                                c)  must not be allowed to come to contact with fertiliser

Contact CSRI if you need any assistance


  • Treat inoculants with care, they contain Live Rhizobia bacteria.
  • Do not expose to extreme heat/ cold.
  • Use within one month of purchase.
  •  Store in a cool place and avoid direct sunlight.
  •  Rhizobium is specific ( apply specific strain for a given legume)
  • Inoculate in a shade & inoculate as much seed that can be planted within 24 hours


Rhizobia inoculant technology is not a cure at all. It does not replace the need for adequate amounts of other plant nutrients/ fertilizers, and or good management practices. It plays a major role in soil improvement and increasing yield, and enhancing farm income. Legume inoculants are high quality cultures of specific strains of root nodule bacteria. Inoculant cultures are under constant testing and are guaranteed to be of high quality.