Rhizobium is a soil bacteria that fix nitrogen from the atmosphere once it is contained inside the leguminous plant roots. Nitrogen fixation can not be performed independently. Therefore, rhizobium needs a host of plants. Rhizobium is a key nitrogen source for agricultural soils including those in arid areas. They turn the dinitrogen into ammonia. Ammonia, being poisonous is absorbed easily into organic compounds.
Leguminous plants are plants capable of fixing the nitrogen in the soil from the environment. Nitrogenous fertilizer is not added in the soil in which leguminous plants are grown because the nitrogen-fixing bacteria reside in the root nodules of the leguminous plants.
Examples – beans, peas, & soybeans, etc.
Importance of Rhizobium
- Rhizobium is the bacteria that live in symbiotic association with the leguminous plants.
- It is found in the root nodules of the leguminous plants and helps in nitrogen fixation.
- Plants cannot fix atmospheric nitrogen on their own, but require it in some form to make amino acids and proteins.
- This nitrogen is made available to the plants by the bacteria Rhizobium.
- Rhizobium multiplies within the cortex cells and forms nodules and the nodules turn pink as the nitrogen fixation starts.
- The fixed nitrogen is beneficial to the legumes and the plants around.
- Rhizobium converts the atmospheric nitrogen into ammonia which is made available to the plants.